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2004 HCUP Nationwide Inpatient Sample (NIS) Comparison Report


HCUP Methods Series 2004 Nationwide Inpatient Sample (NIS) Comparison Report

Report #2007-03

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Healthcare Cost and Utilization Project (HCUP)
Agency for Healthcare Research and Quality
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Recommended Citation: Whalen D, Houchens R, Elixhauser A, 2004 HCUP Nationwide Inpatient Sample (NIS) Comparison Report. HCUP Method Series Report # 2007-03. Online December 2, 2007. U.S. Agency for Healthcare Research and Quality.
Available: http://www.hcup-us.ahrq.gov/reports/methods/methods_topic.jsp



TABLE OF CONTENTS

INDEX OF TABLES

INDEX OF FIGURES 


INTRODUCTION

This report compares estimates calculated from the 2004 Nationwide Inpatient Sample (NIS) with statistics from two comparable databases — the National Hospital Discharge Survey (NHDS) and the Medicare Provider Analysis and Review (MedPAR) — with the objective of assessing potential biases. In addition, NIS estimates were contrasted with summary information from the American Hospital Association (AHA). This report summarizes methods and findings and provides all comparisons in detailed tables in the appendices. Further information on the databases compared in this report and descriptions of analytic methods can be found in previous NIS comparison reports (available at http://www.hcup-us.ahrq.gov/db/nation/nis/nisrelatedreports.jsp). In addition to comparisons with national statistics, these data were also evaluated across several categories, including region, expected payer, hospital characteristics, patient demographics, diagnosis groupings, and procedure groupings.

NIS BACKGROUND

The 2004 NIS was established as part of the Healthcare Cost and Utilization Project (HCUP) to provide data supporting analyses of hospital utilization across the United States. NIS data were selected using a stratified probability sample of hospitals, drawn from a frame of 37 states. Sampling probabilities were calculated to select 20 percent of the universe in each stratum defined by hospital characteristics (region, urban/rural location, number of beds, teaching status, and ownership/control). As a result, the NIS includes approximately 8 million discharges from 994 hospitals, with weights to facilitate national estimates. One of the most distinctive features of the NIS is that its large sample size allows for the study of relatively uncommon disorders, procedures, and hospital types; in fact, NIS estimates can be calculated for any number of special sub-populations. In addition, the NIS contains information on hospital charges and includes all payers.

NIS coverage of United States discharges is impressive, because these 37 states include nearly 78 percent of United States community hospitals, more than 84 percent of all discharges, and nearly 91 percent of the U.S. population during 2004. By region, the sampling frame for the NIS includes states with 98 percent of the population in the Northeast, 99 percent of the population in the Midwest, 81 percent of the South, and 92 percent of the West. Figure 1 displays the geographic distribution of NIS Partners.

The key difference between the NIS and the databases with which it was compared relates to geographic scope. Both the NHDS and the MedPAR are national in coverage; MedPAR data include all Medicare-paid, fee-for-service discharges in the United States, while NHDS data were gathered from a sampling frame of all 50 states plus the District of Columbia. In contrast, the 2004 NIS was drawn from only 37 states (as shown in Figure 1); these states comprise 75.5% of all U.S. hospitals and 87.5% of the U.S. population. This difference may be a factor for researchers who require comprehensive geographic representation. Some significant differences between the states excluded and included in the NIS may explain several of the observed differences between the databases described in this report.

NIS states are disproportionately the more densely populated states. The average population density of NIS states was 115.1 persons per square mile in 2004. This compares with a national average of 83.0 persons per square mile and an average population density for non-NIS states of 38.5 persons per square mile. Of the 10 most densely populated states, all but two were included in the NIS. These NIS states, and their rank in terms of population density order, are: New Jersey (1), Rhode Island (2), Massachusetts (3), Connecticut (4), Maryland (5), New York (7), Florida (8), and Ohio (9). At the other end of the spectrum, only four of the 10 least populous states were included in the NIS: Utah (41), Nebraska (42), Nevada (43), and South Dakota (46).1

Figure 1. States Participating in the NIS, 2004 (text version)

Figure 1: Map of states participating in the 2004 NIS

Because of these population differences between NIS and non-NIS states, the NIS sampling frame begins with few hospitals in sparsely populated areas. Even weighting the discharges from rural states does not adequately account for the remote areas of the country, which include a disproportionate number of the smallest hospitals. The most rural states included in the sample, Nevada and South Dakota, have population densities of 21.3 and 10.2 persons per square mile, respectively. This contrasts with population densities of 1.1, 5.2, and 6.4 persons per square mile in Alaska, Wyoming, and Montana, which are not included in the sample.2

1Source of state rankings: State and Metropolitan Area Data Book - 5th Edition and the Annual Estimates of the Population for the United States. December 22, 2005. https://www2.census.gov/programs-surveys/popest/tables/2000-2005/state/totals/nst-est2005-01.xls.
The three most populous states not included in the NIS were Pennsylvania (rank 6), Alabama (rank 23), and Louisiana (rank 24). The six least populous states not included in the NIS were Maine (rank 40), Montana (rank 44), Delaware (rank 45), Alaska (rank 47), North Dakota (rank 48), and Wyoming (rank 50).

2These three states were ineligible for HCUP inclusion because none collected all-payer hospital discharge data for the year 2004.

One impact of the specific subset of states selected for the NIS was an over-representation of Medicare patients in managed care. In the 37 states included in the 2004 NIS, the market penetration of managed care providers for Medicare enrollees averaged 13.5 percent. In contrast, for the 13 states not included in the NIS, the mean market penetration of managed care providers was only 5.5 percent.

It is important to note that NIS data differed in scope from the comparison databases in several ways:

AHA BACKGROUND

For 2004, the American Hospital Association (AHA) Annual Survey Database (also known as the AHA Annual Survey and the AHA Survey of Hospitals) included records for 4,836 hospitals. The AHA Survey data report discharges and inpatient days (overall, Medicare, and Medicaid), as well as hospital information such as bed counts, employment, and payroll. In addition, hospitals indicate specific services offered. The sampling frame for the NIS is based on AHA Survey data.

NHDS BACKGROUND

In 2004, the National Center for Health Statistics drew a sample of 319,530 short-stay discharges from 426 hospitals, including both general and children’s hospitals for the NHDS data set. Statistics from the NHDS are considered geographically representative because the NHDS sampling frame was relatively unrestricted. The NHDS usually presents diagnoses and procedures in the order in which they were listed on the abstract form, with three specific exceptions: (1) code V27, outcome of delivery, was re-ordered as the principal diagnosis when it appeared as a secondary diagnosis; (2) acute myocardial infarction codes were re-ordered as the principal diagnosis when this condition appeared as a secondary diagnosis and another circulatory disease appeared on the record; and (3) if a symptom appeared as a first-listed diagnosis and a diagnosis appeared as a secondary code, the diagnosis replaced the symptom, which was moved to appear after the diagnosis.

MedPAR BACKGROUND

Obtained from the Centers for Medicare and Medicaid Services (CMS), MedPAR data include all paid fee-for-service Medicare discharges from Medicare-certified, short-stay U.S. hospitals. For calendar year 2004, 12.7 million discharges from U.S. community hospitals were included. One important characteristic of MedPAR data is that the database under-reported total Medicare discharges by omitting most managed care discharges (approximately 14 percent of Medicare patients). This particular omission has significant implications for the various comparisons between the MedPAR and NIS data files.

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METHODS

Statistics compared in the NIS, NHDS, and MedPAR databases included total number of discharges, average length of stay, in-hospital mortality rates, and average total charges (NIS and MedPAR only). These measures of utilization and outcomes were selected because they are common in health services research and serve important roles in health policy and resource planning analyses.

Both the NIS and NHDS are samples, and statistics derived from them are estimates. Therefore, comparisons between NIS and NHDS estimates utilized two-sample t-tests. MedPAR data, in contrast, are not derived from a sample. The NIS-MedPAR comparisons employed one-sample t-tests, which are useful in comparing an entire population (MedPAR) with sample estimates (NIS).

The report cautions that estimates cannot be expected to be identical when two different samples are drawn. When viewing results, readers should note that statistically significant differences between the NIS and the NHDS can be expected for a number of reasons. These include:

MAJOR FINDINGS

Considering all of these possible reasons for significant differences among the samples, data analyses revealed remarkable similarity among the estimates. NIS estimates of essential health care policy variables (i.e., number of inpatient discharges, in-hospital mortality, length of stay, and charges) were accurate and precise.

NIS-AHA Comparisons

Tables 1-6 summarize comparisons between the NIS and the AHA Annual Survey. NIS hospitals resembled typical hospitals in the AHA universe in bed size and most characteristics, although NIS hospitals were more active, had higher staffing rates, and had larger expenditures compared to the AHA universe. NIS facilities also admitted and discharged more patients and had higher expenditures and larger payrolls than hospitals in the AHA universe. NIS hospitals also tended to offer slightly more high-technology services, as compared with the universe. While NIS hospitals had more full-time equivalent (FTE) RNs per 1,000 patient days, there were fewer more FTE employees per bed. In addition, Medicaid patients were less prevalent in NIS hospitals than in all AHA facilities.

Nearly all NIS discharge estimates closely align with the discharge counts from the AHA Survey. This is not surprising, because NIS sampling strata and NIS discharge weights were based on AHA Annual Survey results. The AHA-derived sampling weights in the NIS yield discharge counts consistent with the AHA universe, overall, by region, and for most categories of hospital control and type. Of the 35 discharge comparisons shown in Table 5, only one significant difference was observed: the NIS discharge estimate for proprietary hospitals with more than 500 beds was moderately larger than the AHA total.

NIS-NHDS Comparisons

NIS-NHDS comparisons are presented in Table 7 through Table 12. NIS and NHDS estimates agreed in overall comparisons and across patient categories. This was also true for most hospital comparisons and specific diagnosis and procedure categories. Overall, agreements were observed for 72 percent of the discharge comparisons and 98 percent of the average length of stay (ALOS) comparisons. The degree of consistency for in-hospital mortality rates was also high: no significant differences were found with region and patient categories, and estimates agreed for 76 percent of hospital category comparisons. Of the NIS-NHDS differences discovered, most occur in diagnosis and procedure groupings.

NIS-MedPAR Comparisons

As shown in Tables 13-19, with the exception of discharge counts, NIS estimates of Medicare measures were generally consistent with MedPAR statistics. NIS discharge estimates were uniformly higher than the MedPAR numbers by approximately 15 percent, consistent with the omission of most managed care clients from the MedPAR. While 12.9 percent of Medicare patients were enrolled in managed care programs, the MedPAR data contain virtually no managed care discharges (only 1,313 out of 12,660,083 total discharges, or 0.01 percent).

Key Findings

The following sections provide summary highlights of key findings from this comparative analysis:

Summary of overall and regional comparisons:

Comparisons by hospital characteristics:

Comparisons by patient characteristics:

Comparisons by diagnosis and procedure categories:

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DISCUSSION

Each data source possesses distinct strengths and weaknesses and may be regarded as the optimum choice for answering different research questions. In general, NIS estimates of essential health care policy variables are accurate and precise. The NIS offers a large sample that might allow for the study of disorders, procedures, and hospital types that occur with low frequency in other databases. NIS estimates can be calculated for thousands of special sub-populations that may be of interest to researchers.

NIS Strengths

While the previous discussion focused on differences between the NIS and other data sources, it should be noted that these differences are only of concern when there is a reason to expect that geographic region might relate to the variable of interest. We must emphasize that the NIS provides a large sample size that tends to yield estimates with much smaller standard errors than does a sample such as the NHDS. Without a sample of several million, as provided by the NIS, estimates for less common procedures and diagnoses are unreliable. While the NIS may over-represent urban areas, the prevalence of higher-density states in the NIS yields data on atypical conditions rarely included in a smaller sample.

NIS discharge estimates were quite similar to AHA numbers, regardless of the hospital characteristics. NIS statistics were generally parallel to NHDS estimates, as well. When estimating ALOS and in-hospital mortality for the nation, or within any major categories, NIS rates were consistent with the NHDS data. Because NIS estimates have greater precision — the result of the large sample size — it may be preferred for certain analyses based on relatively uncommon conditions. Furthermore, the NIS contains total hospital charges, while the NHDS does not. For analyses involving charges on all payers, the NIS is the only choice.

The NIS provides a large sample of Medicare discharges both in managed care and fee-for-service plans; it would therefore be the choice of researchers who wished to include all discharges regardless of payment type. Inclusion of Medicare managed care discharges leads to discrepancies in estimated discharge counts, but most other NIS Medicare estimates were similar to MedPAR statistics, particularly with respect to comparisons by hospital characteristics.

NIS Weaknesses

NIS discharge estimates vary from NHDS estimates on the dimension of hospital size: the NIS includes more discharges from large hospitals than the NHDS. In contrast, NIS discharge estimates were similar to AHA Survey results. Because the NHDS uses a more geographically complete sampling frame, it might be preferable for researchers in certain cases where regional differences are expected.

The NIS also contains significant numbers of discharges for which race was missing (26 percent). While the NHDS also suffers from this problem (24 percent of discharges without race), race information is present for nearly all MedPAR discharges.

Because of the limitations of the NIS sampling frame, the NIS exaggerates the discrepancy between total Medicare discharges and the MedPAR’s primarily fee-for-service population. The MedPAR database provides no estimate for managed care participants, while the NIS database may over-estimate the number of discharges in managed care.

The NHDS sample and MedPAR data were drawn from all 50 states, while only 37 states were included in the NIS database. However, for 2004, NIS states encompassed nearly 78 percent of all short-stay hospitals and more than 84 percent of all United States discharges. The NIS contains charges for each hospital stay, all payers, and a large sample of discharges. In contrast, the NHDS includes a smaller number of discharges, does not contain charges, but does sample from all 50 states. The MedPAR database is limited to Medicare discharges and contains all Medicare patients covered by the fee-for-service program, but excludes Medicare patients enrolled in managed care plans. Thus, the appropriateness of each of these databases is dependent on researcher needs and institutional priorities. In conclusion, the NIS appears to provide reliable national estimates when compared with these other national data sources along the dimensions examined in this report.

Contrasting Findings from the Previous NIS Comparisons

NIS-NHDS Evaluations

Estimates of most outcome measurements from the 2004 NIS and NHDS data were consistent, as were previous years’ evaluations. Overall, the discharge and ALOS estimates from these two databases were similar for 2000 through 2004. NIS and NHDS estimates of ALOS were almost indistinguishable. Of more than 80 comparisons, few significant ALOS differences were observed in any year. When considered by year, there were four differences with the 2000 data, two with the 2001 data, one with the 2002 data, two with the 2003 data, and three with the 2004 data. NIS and NHDS discharge estimates from 2000 through 2004 were also similar, although in all years, the data sources generated divergent statistics for large and small hospitals.

Similarly, in-hospital mortality rate estimates for 2004 data were consistent with previous data across hospital and patient categories. Of all hospital comparisons, only two significant mortality differences were observed, and two meaningful mortality rate differences were discovered for patient categories. These outcomes were similar to the 2001-2003 analyses and represented improvements over the 2000 assessments. For diagnosis and procedure comparisons, the 2004 in-hospital mortality rate evaluations were similar to comparisons for 2003, 2002, and 2000 (2001 now appears to be an aberration). No trend appears with these differences. The number of categories with lower NIS rates was about the same as the number of categories with higher NIS rates.

Discrepancies in in-hospital mortality rate comparisons may be related to differences in the hospitals included in the two samples. The NIS tends to have better representation from larger hospitals and better captures less common diagnoses, which tend to have higher mortality rates.3 Furthermore, because the NIS retains all discharges from a hospital, it was not possible to exclude some of the higher mortality cases that might have been treated in skilled-nursing facilities and other long-term care units within the hospital. Differences may also be linked to a hospital’s teaching status or location, although this cannot be verified because the NHDS does not report this information.

3The average in-hospital mortality rate for discharges associated with the 50 most frequent diagnosis groups was 2.1 percent. This compares to an average of 3.9 percent for discharges associated with one of the 50 least frequent diagnosis groups.

NIS-MedPAR Evaluations

As discussed previously, NIS Medicare discharge estimates were higher than MedPAR counts for almost all categories. Inconsistencies were noted for nearly all discharge counts; the overall discrepancy rate was 12 percent. This discrepancy was also true for earlier years: the difference in 2003 was 14 percent, while in 2000, 2001, and 2002, the difference was 22, 21, and 20 percent, respectively. In 1999, the figure was lower, at 12 percent. The growth from 1999 to 2000 may have been caused by increases in Medicare managed care market penetration, particularly within NIS states, while the slow decline after 2000 reflects a decrease in market penetration in later years.

While differences emerged for discharge statistics, other estimates were similar between the two data sources. Most NIS estimates of discharge proportions, ALOS, in-hospital mortality rates, and average total hospital charges were comparable to MedPAR statistics. Mortality rates were quite similar to earlier years.

The overall ALOS statistics were consistent for the 2004 NIS and MedPAR data; ALOS comparisons were similar to the 2003 and 2002 results, which demonstrated fewer differences than in previous reports. These findings for the latest three years demonstrate fewer differences when compared with the 2000 data. The overall NIS Medicare estimate of ALOS in 2000 was significantly shorter in duration than the MedPAR average. Finally, average hospital charge comparisons revealed few differences in any year.

Conclusion

Each of the data sources discussed has its strengths and weaknesses, and each may be the preferred choice for different research questions. The NIS offers a large sample that enables study of low incidence disorders and less common procedures; NIS estimates can be calculated for literally thousands of special sub-populations that may be of interest to researchers. In addition, NIS hospitals accurately reflect the universe of United States hospitals, particularly the relative mix of large and small hospitals. Therefore, the NIS may be more appropriate when hospital type and size are important considerations.

In contrast, the NHDS and MedPAR both offer data drawn from all 50 states, rather than the 37 states that make up the 2004 NIS. Where a comprehensive geographic representation is more important than a large sample size, and the question under study requires all age groups, the NHDS might be preferable. In the same situation, if only Medicare clients are of interest, the MedPAR data set might be preferable.

The NIS is not without bias: specifically, it over-represents large hospitals and urban states and under-represents smaller hospitals and rural/frontier states. It does, however, provide a useful data source for answering many research questions. The source of the few differences that do exist between the NIS and NHDS are areas that warrant further investigation. The relationship between hospital size and treatment patterns is an example.

As for which of the data sources discussed is preferable or better, the answer depends on the needs of the researcher. The intended use of the data is the most critical factor in determining which data source will be most valuable. In general, the NIS estimates of variables essential to health care policy – including in-hospital mortality, inpatient population size, length of stay, and costs – are accurate and precise. Statistics can be calculated for large groups ranging from the inpatient population of the United States, as well as for small subsets featuring specific conditions. The characteristics documented in this report suggest that the 2004 NIS is a valuable tool for researchers and policy makers alike.

REFERENCES

Centers for Medicare & Medicaid Services (2006). CMS State County File, 2002-2005. Washington, DC: CMS. http://www.cms.hhs.gov/HealthPlanRepFileData/Downloads/SC-2005.zip (Accessed August 2, 2006.)

Korn, E. L. & Graubard, B. I. (1999). Analysis of Health Surveys. New York: John Wiley & Sons.

National Center for Health Statistics (2004). National Hospital Discharge Survey Public Use Data File Documentation: 2004. Washington, DC: U.S. Department of Health and Human Services, National Center for Health Statistics.

Spetz, J. & Baker, L. Has Managed Care Affected the Availability of Medical Technology? Public Policy Institute of California, 1999. http://www.ppic.org/content/pubs/report/R_599JSR.pdf. Exit Disclaimer (Accessed July 10, 2008.)

U.S. Agency for Healthcare Research and Quality (2006). Design of the Nationwide Inpatient Sample (NIS), 2004. Rockville, MD. http://hcup-us.ahrq.gov/db/nation/nis/reports/NIS_2003_Design_Report_Edited_012506.pdf (Accessed December 4, 2006.)

U.S. Census Bureau (2006). Table 3: Annual Estimates of the Population by Sex, Race and Hispanic or Latino Origin for the United States: April 1, 2000 to July 1, 2005 (NC-EST2005-03). Washington, DC: Population Division, U.S. Census Bureau (2006).

U.S. Census Bureau (2006). State and Metropolitan Area Data Book – 5th Edition. Washington, DC: U.S. Bureau of the Census.

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Table 1. Number of Hospitals in NIS Frame and Universe, 2004
  2004 NIS Frame1(Weighted) 2004 NIS Frame 1 (Unweighted) 2004 AHA Universe
U.S. 4,906 1,004 4,961
Region
Northeast 653 135 653
Midwest 1,411 285 1,411
South 1,937 397 1,937
West 905 187 905
Hospital Control
Public 1,141 235 1,126
Not for-profit 2,942 601 2,937
Propietary 823 168 843
Location / Teaching Status
Rural 2,026 413 2,026
Small 905 184 1,234
Medium 485 99 449
Large 636 130 343
Urban, non-teaching 2,071 424 2,071
Small 850 173 864
Medium 586 121 615
Large 635 130 592
Urban, teaching 809 167 809
Small 249 51 229
Medium 250 52 248
Large 310 64 332

Note: Significance tests were not performed because AHA numbers are not sample statistics.
1The 2004 frame contains 37 states.

Table 2. NIS Hospitals and AHA Universe Comparisons, 2004
  NIS Universe
High Tech Index1 (mean) 2.59 2.45
High Tech Index1 (median) 2.00 2.00
Neonatal ICUs2 (pct) 18.92 18.65
Cardiac Catheterization2 (pct) 25.00 23.91
CT Scanners2 (pct) 78.09 74.68
MRIs2 (pct) 54.88 50.44
Open Heart Surgeries2 (pct) 20.42 20.02
Transplant Services2 (pct) 7.17 7.28
Intensity Modulated Ray Radiation Therapy2 (pct) 15.24 15.37
Extracorporeal Shock Wave Lithotripsy2 (pct) 21.41 20.02
PET Scanners2 (pct) 17.63 14.86
 
Pediatric Specialty Hospitals (pct) 1.20 1.62
Burn Units (pct) 4.48 4.55
Rehabilitation Units (pct) 22.51 24.79
Alc/Chem Dep Services (pct) 8.47 8.21
Trauma Centers (pct) 27.19 28.76
Emergency Departments (pct) 80.58 77.89

Note: Significance tests were not performed because AHA numbers are not sample statistics.
1Prior to 2004, the index included Angioplasty services.
2High technology service - used in the "High Tech Index."

Table 3. NIS Hospitals and AHA Universe Comparisons, 2004
  NIS Mean Universe Mean NIS Median Universe Median
Hospital Admissions 7,310.88 7,011.17 3,801.50 3,560.00
Hospital Discharges 7,310.88 7,011.17 3,801.50 3,560.00
Hospital Discharges1 8,159.49 7,802.22 4,266.00 3,936.00
Average Length of Stay 5.66 5.93 4.37 4.42
Average Length of Stay1 5.27 5.55 4.01 4.03
Births 848.61 791.05 323.50 275.00
Percent Medicare Days 53.86 54.45 54.02 55.25
Percent Medicare Discharges 48.14 48.52 48.24 48.29
Percent Medicare Discharges2 44.73 45.21 43.21 43.91
Percent Medicaid Days 15.23 15.00 13.14 12.84
Percent Medicaid Discharges 16.08 15.78 15.07 15.09
Percent Medicaid Discharges2 14.53 14.30 13.66 13.88
Hospital Beds 153.83 149.92 92.00 88.00
Occupancy Rate 54.72 52.30 56.33 53.68
Inpatient Surgeries 2,099.41 2,058.12 1,022.00 940.00
FTE1 867.80 837.98 434.00 398.00
FTE1 per Bed 5.57 5.30 5.21 4.84
RN FTE1 per 1000 Patient Days 4.29 3.24 2.97 2.91
Intern-Resident FTE1 per 100 Beds 5.61 6.32 0.00 0.00
Intern-Resident FTE1 per 100 Beds (Teaching Hospitals) 28.50 34.10 14.66 11.36
Total Hospital Expenses [dollars] 101,600,413 96,080,119 48,015,871 39,108,434
Hosp. Expenses per Bed [dollars] 629,176 557,231 552,169 505,981
Total Hospital Payroll [dollars] 41,315,160 39,081,256 19,424,823 16,149,252
Hosp. Payroll per Bed [dollars] 253,704 224,590 222,248 202,095

Note: Significance tests were not performed because AHA numbers are not sample statistics.
1Adjusted for well newborns.
2Full-time equivalents.

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Table 4. NIS and AHA Comparisons by Overall, 2004
  Number of Discharges in Thousands (Standard Error) Average Length of Stay in Days (Standard Error)
NIS AHA NIS AHA
Overall 38,661 (707) 39,065 4.65 (0.03) 4.54**
 
Region
Northeast 7,650 (329) 7,649 5.28 (0.12) 5.14
South 8,913 (313) 8,913 4.44 (0.06) 4.38
Midwest 14,733 14,733 4.67 (0.05) 4.54*
West 7,364 (297) 7,364 4.22 (0.07) 4.09

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.

Table 5. NIS and AHA Comparisons by Hospital Ownership, 2004
Hospital Ownership Number of Discharges in Thousands (Standard Error) Average Length of Stay in Days (Standard Error)
NIS AHA NIS AHA
Total Public 5,382 (553) 5,238 4.82 (0.15) 4.80
1-99 Beds 1,190 (99) 1,107 3.72 (0.06) 4.03**
100-199 Beds 889 (133) 894 4.26 (0.16) 4.41
200-299 Beds 711 (160) 607 4.32 (0.17) 4.53
300-499 Beds 1,261 (257) 1,271 5.39 (0.22) 5.11
500+ Beds 1,329 (317) 1,357 5.92 (0.33) 5.53
Total Private Non-Profit 28,274 (900) 28,328 4.64 (0.04) 4.49**
1-99 Beds 2,634 (147) 2,629 3.78 (0.07) 3.87
100-199 Beds 4,886 (299) 5,041 4.29 (0.07) 4.19
200-299 Beds 5,520 (480) 5,755 4.64 (0.10) 4.37*
300-499 Beds 8,301 (737) 7,988 4.60 (0.08) 4.46
500+ Beds 6,930 (760) 6,912 5.26 (0.09) 5.09
Total Proprietary 5,004 (335) 5,094 4.54 (0.08) 4.50
1-99 Beds 815 (94) 821 4.42 (0.27) 4.41
100-199 Beds 1,753 (152) 1,671 4.28 (0.11) 4.31
200-299 Beds 1,109 (202) 1,226 4.50 (0.14) 4.43
300-499 Beds 1,202 (213) 922 4.96 (0.14) 4.69
500+ Beds 123 (123) 452** 5.18 (0.00) 5.121

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.

Table 6. NIS and AHA Comparisons by Location / Teaching Status, 2004
Location / Teaching Status Number of Discharges in Thousands (Standard Error) Average Length of Stay in Days (Standard Error)
  NIS AHA NIS AHA
Rural 5,160 (217) 5,160 3.92 (0.05) 4.23**
small 1,186 (54) 1,225 3.46 (0.05) 3.66**
medium 1,515 (130) 1,416 3.66 (0.05) 3.94**
large 2,459 (250) 2,518 4.30 (0.09) 4.67**
Urban, Non-teaching 16,669 (444) 16,668 4.48 (0.04) 4.35**
small 1,847 (139) 1,808 4.28 (0.14) 4.26
medium 4,659 (249) 4,728 4.31 (0.07) 4.13*
large 10,162 (436) 10,131 4.59 (0.06) 4.47
Urban, Teaching 16,831 (505) 16,831 5.04 (0.06) 4.81**
small 2,129 (277) 2,333 4.73 (0.20) 4.44
medium 4,283 (539) 4,607 4.84 (0.12) 4.65
large 10,418 (781) 9,890 5.19 (0.08) 4.98*

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.

Table 7. NIS and NHDS Comparisons by Overall, 2004
Overall Number of Discharges in Thousands (Standard Error) Average Length of Stay in Days (Standard Error) In-Hospital Mortality Rate Percent (Standard Error)
NIS NHDS NIS NHDS NIS NHDS
Overall 38,661 (707) 38,772 (1,738) 4.63 (0.03) 4.64 (0.32) 2.13 (0.03) 2.10 (0.13)
Region
Northeast 7,650 (329) 8,089 (685) 5.25 (0.12) 5.211 (c) 2.46 (0.15) 2.18 (0.26)
South 8,913 (313) 8,482 (972) 4.42 (0.06) 4.221(c) 1.95 (0.05) 2.411 (c)
Midwest 14,733 (452) 14,642 (932) 4.65 (0.05) 4.75 (0.49) 2.19 (0.04) 1.93 (0.17)
West 7,364 (297) 7,557 (605) 4.20 (0.07) 4.29 (0.54) 1.87 (0.06) 2.01 (0.22)

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.
(c) A valid standard error could not be calculated.

Table 8. NIS and NHDS Comparisons by Control, 2004
Control Number of Discharges in Thousands (Standard Error) Average Length of Stay in Days (Standard Error) In-Hospital Mortality Rate Percent (Standard Error)
NIS NHDS NIS NHDS NIS NHDS
Total Public 5,382 (553) 4,531 (207) 4.80 (0.15) 4.72 (0.33) 2.11 (0.08) 2.01 (0.13)
1-99 Beds 1,190 (99) 1,217 (59) 3.69 (0.06) 3.61 (0.27) 2.23 (0.10) 2.43 (0.16)
100-199 Beds 889 (133) 778 (39) 4.24 (0.16) 4.50 (0.34) 2.31 (0.09) 1.82** (0.13)
200-299 Beds 711 (160) 409 (22) 4.30 (0.17) 4.65 (0.38) 1.77 (0.20) 2.08 (0.16)
300-499 Beds 1,261 (257) 1,462 (70) 5.37 (0.22) 5.33 (0.39) 2.20 (0.29) 1.89 (0.12)
500+ Beds 1,329 (317) 663* (34) 5.91 (0.33) 5.73 (0.44) 1.98 (0.14) 1.67 (0.12)
Total Private Non-Profit 28,274 (900) 29,232 (1,312) 4.61 (0.04) 4.62 (0.32) 2.15 (0.05) 2.16 (0.13)
1-99 Beds 2,634 (147) 6,429** (292) 3.75 (0.07) 3.96 (0.28) 2.06 (0.06) 2.22 (0.14)
100-199 Beds 4,886 (299) 6,723** (305) 4.27 (0.07) 4.61 (0.32) 2.10 (0.07) 1.83 (0.11)
200-299 Beds 5,520 (480) 6,558 (298) 4.62 (0.10) 4.63 (0.32) 2.18 (0.20) 2.14 (0.13)
300-499 Beds 8,301 (737) 5,619** (256) 4.57 (0.08 4.85 (0.34) 2.12 (0.07) 2.45 (0.15)
500+ Beds 6,930 (760) 3,901** (179) 5.24 (0.09) 5.36 (0.38) 2.24 (0.07) 2.23 (0.14)
Total Proprietary 5,004 (335) 5,008 (228) 4.52 (0.08) 4.70 (0.33) 2.01 (0.07) 1.84 (0.11)
1-99 Beds 815 (94) 1,301** (63) 4.40 (0.27) 4.76 (0.35) 2.01 (0.14) 1.84 (0.12)
100-199 Beds 1,753 (152) 2,223* (104) 4.27 (0.11) 4.58 (0.33) 2.04 (0.09) 1.58** (0.10)
200-299 Beds 1,109 (202) 729 (37) 4.49 (0.14) 4.74 (0.36) 1.97 (0.13) 2.20 (0.15)
300-499 Beds 1,202 (213) 753* (38) 4.94 (0.14) 4.92 (0.38) 2.05 (0.13) 2.26 (0.16)
500+ Beds 123 (123) 01 (a) 5.16 (0.00) 0.001(a) 1.58 (0.00) 0.001 (a)

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.
(a) Because of very small sample size, the NHDS estimate and standard error were unreliable and not reported.

Table 9. NIS and NHDS Comparisons by Patient Characteristics, 2004
  Number of Discharges in Thousands (Standard Error) Average Length of Stay in Days (Standard Error) In-Hospital Mortality Rate Percent (Standard Error)
NIS NHDS NIS NHDS NIS NHDS
Age Group
0-15 Years 6,294 (216) 6,648 (302) 3.61 (0.07) 3.79 (0.27) 0.41 (0.02) 0.46 (0.02)
16-44 Years 10,711 (241) 10,630 (480) 3.65 (0.05) 3.67 (0.26) 0.43 (0.01) 0.36* (0.02)
45-64 Years 8,546 (177) 8,322 (377) 4.96 (0.05) 5.00 (0.35) 1.88 (0.05) 1.87 (0.12)
65+ Years 13,059 (272) 13,170 (594) 5.71 (0.04) 5.63 (0.39) 4.51 (0.06) 4.47 (0.28)
Gender
Female 22,757 (437) 22,908 (1,029) 4.41 (0.03) 4.40 (0.31) 1.82 (0.03) 1.75 (0.11)
Male 15,773 (287) 15,863 (714) 4.96 (0.04) 4.98 (0.35) 2.58 (0.04) 2.61 (0.16)
Race
White 18,987 (724) 23,068* (1,528) 4.73 (0.04) 4.67 (0.47) 2.40 (0.05) 2.24 (0.21)
Black 4,159 (296) 4,545 (322) 5.47 (0.10) 5.27 (0.60) 2.11 (0.08) 1.94 (0.19)
Other 5,346 (340) 1,804** (248) 4.28 (0.07) 4.591 (c) 1.46 (0.06) 1.671 (c)
Unknown 10,168 (728) 9,354 (1,201) 4.28 (0.06) 4.261 (c) 1.97 (0.05) 1.921 (c)

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.
(c) A valid standard error could not be calculated.

Table 10. NIS and NHDS Comparisons by Principal Payer, 2004
Principal Payer Number of Discharges in Thousands (Standard Error) Average Length of Stay in Days (Standard Error) In-Hospital Mortality Rate Percent (Standard Error)
NIS NHDS NIS NHDS NIS NHDS
Medicare 14,028 (286) 13,751 (676) 5.77 (0.04) 5.73 (0.45) 3.99 (0.05) 4.05 (0.28)
Medicaid 7,344 (263) 7,286 (611) 4.36 (0.07) 4.431 (c) 0.90 (0.03) 0.95 (0.11)
Private Insurance 13,956 (427) 13,580 (898) 3.75 (0.03) 3.79 (0.40) 1.02 (0.03) 0.98 (0.09)
Self Pay 1,933 (95) 1,750 (122) 3.86 (0.10) 3.90 (0.46) 1.49 (0.07) 1.11** (0.11)
No Charge 147 (44) 118 (22) 4.89 (0.21) 4.931 (c) 1.37 (0.21) 1.691 (c)
Other 1,185 (80) 2,284* (420) 4.36 (0.10) 4.341 (c) 1.79 (0.14) 1.431 (c)
Missing 14 (12) 01 (a) 6.83 (0.73) 0.001 (a) 3.00 (0.37) 0.00 (a)

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.
(a) Because of very small sample size, the NHDS estimate and standard error were unreliable and not reported.
(c) A valid standard error could not be calculated.

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Table 11. NIS and NHDS Comparisons by Principal Diagnosis, 2004
Principal Diagnosis Number of Discharges in Thousands (Standard Error) Average Length of Stay in Days (Standard Error) In-Hospital Mortality Rate Percent (Standard Error)
NIS NHDS NIS NHDS NIS NHDS
218: Liveborn 4,249 (144) 3,917 (180) 3.26 (0.06) 3.31 (0.23) 0.35 (0.01) 0.36 (0.02)
122: Pneumonia (except that caused by tuberculosis or sexually transmitted disease) 1,213 (20) 1,344 (65) 5.73 (0.04) 5.56 (0.41) 4.74 (0.07) 5.38 (0.36)
101: Coronary atherosclerosis and other heart disease 1,192 (48) 1,208 (58) 3.42 (0.04) 3.31 (0.25) 0.57 (0.02) 0.44** (0.03)
108: Congestive heart failure; nonhypertensive 1,104 (24) 1,131 (55) 5.48 (0.05) 5.35 (0.40) 4.05 (0.06) 3.70 (0.25)
102: Nonspecific chest pain 845 (24) 54** (5) 1.85 (0.01) 1.421 (c) 0.06 (0.00) 0.161 (c)
193: OB-related trauma to perineum and vulva 785 (33) --1 (a) 2.02 (0.01) --1 (a) 0.00 (0.00) --1 (a)
195: Other complications of birth; puerperium affecting management of mother 758 (28) 62** (5) 2.73 (0.03) 3.421 (c) 0.02 (0.00) 0.07** (0.00)
69: Affective disorders 708 (40) 866** (43) 7.30 (0.19) 7.52 (0.56) 0.03 (0.01) 0.02 (0.00)
100: Acute myocardial infarction 695 (22) 732 (37) 5.35 (0.06) 5.72 (0.44) 7.17 (0.13) 8.67* (0.62)
106: Cardiac dysrhythmias 693 (17) 746 (38) 3.54 (0.03) 3.55 (0.27) 1.19 (0.03) 1.26 (0.09)
203: Osteoarthritis 659 (28) 695 (35) 3.84 (0.04) 3.87 (0.30) 0.13 (0.01) 0.21** (0.01)
205: Spondylosis; intervertebral disc disorders; other back problems 615 (22) 649 (33) 3.15 (0.04) 3.00 (0.24) 0.19 (0.01) 0.15* (0.01)
237: Complication of device; implant or graft 601 (20) 565 (29) 5.90 (0.07) 5.99 (0.47) 1.85 (0.05) 1.60 (0.11)
127: Chronic obstructive pulmonary disease and bronchiectasis 555 (11) 635* (33) 4.92 (0.04) 4.72 (0.37) 2.26 (0.06) 2.35 (0.17)
55: Fluid and electrolyte disorders 554 (11) 761** (38) 3.78 (0.03) 3.53 (0.27) 2.10 (0.06) 1.66** (0.12)
109: Acute cerebrovascular disease 545 (12) 540 (28) 6.33 (0.07) 6.33 (0.50) 10.69 (0.19) 10.63 (0.80)
181: Other complications of pregnancy 511 (17) 205** (13) 2.45 (0.02) 2.49 (0.25) 0.03 (0.00) 0.04 (0.00)
159: Urinary tract infections 506 (10) 603** (31) 4.47 (0.03) 4.54 (0.36) 1.37 (0.04) 1.67* (0.12)
197: Skin and subcutaneous tissue infections 505 (10) 579* (30) 4.69 (0.04) 4.73 (0.37) 0.42 (0.02) 0.32** (0.02)
254: Rehabilitation care; fitting of prostheses; and adjustment of devices 489 (32) 513 (27) 12.57 (0.23) 11.90 (0.92) 0.57 (0.07) 0.52 (0.03)
50: Diabetes mellitus with complications 488 (10) 494 (26) 5.40 (0.05) 5.19 (0.41) 1.11 (0.03) 0.64** (0.04)
238: Complications of surgical procedures or medical care 457 (12) 442 (24) 6.22 (0.06) 6.05 (0.49) 1.42 (0.05) 2.00** (0.15)
189: Previous C-section 455 (17) --1 (a) 2.87 (0.02) --1 (a) 0.00 (0.00) --1 (a)
149: Biliary tract disease 453 (9) 459 (25) 4.19 (0.03) 4.14 (0.34) 0.72 (0.03) 0.70 (0.05)
2: Septicemia (except in labor) 451 (11) 413 (22) 8.58 (0.09) 8.40 (0.67) 17.84 (0.26) 17.60 (1.38)

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.
(a) Because of very small sample size, the NHDS estimate and standard error were unreliable and not reported.
(c) A valid standard error could not be calculated.

Table 12. NIS and NHDS Comparisons by Principal Procedure, 2004
Principal Diagnosis Number of Discharges in Thousands (Standard Error) Average Length of Stay in Days (Standard Error) In-Hospital Mortality Rate Percent (Standard Error)
NIS NHDS NIS NHDS NIS NHDS
137: Other procedures to assist delivery 1,472 (65) 1,007** (49) 2.12 (0.01) 2.10 (0.16) 0.00 (0.00) 0.00 (0.00)
134: Cesarean section 1,268 (48) 1,229 (59) 3.70 (0.04) 3.69 (0.27) 0.01 (0.00) 0.01 (0.00)
115: Circumcision 1,102 (46) 1,086 (53) 2.68 (0.03) 2.59 (0.19) 0.00 (0.00) 0.00* (0.00)
70: Upper gastrointestinal endoscopy; biopsy 731 (22) 716 (36) 5.23 (0.11) 5.38 (0.41) 1.49 (0.05) 0.96** (0.07)
45: Percutaneous transluminal coronary angioplasty (PTCA) 720 (43) 596* (31) 2.76 (0.04) 3.05 (0.24) 0.74 (0.03) 0.71 (0.05)
140: Repair of current obstetric laceration 680 (39) 799* (40) 2.14 (0.01) 2.11 (0.17) 0.00 (0.00) 0.00 (0.00)
216: Respiratory intubation and mechanical ventilation 676 (19) 611 (32) 10.96 (0.25) 10.97 (0.84) 26.09 (0.60) 26.67 (1.97)
47: Diagnostic cardiac catheterization; coronary arteriography 638 (25) 584 (30) 3.62 (0.05) 3.77 (0.30) 0.91 (0.03) 1.04 (0.07)
124: Hysterectomy; abdominal and vaginal 574 (19) 595 (31) 2.72 (0.03) 2.71 (0.22) 0.08 (0.00)) 0.08 (0.00)
222: Blood transfusion 568 (20) 542 (28) 5.67 (0.06) 5.84 (0.46) 5.10 (0.11) 5.05 (0.38)
228: Prophylactic vaccinations and inoculations 550 (60) 535 (28) 2.45 (0.05) 2.48 (0.20) 0.01 (0.00) 0.00** (0.00)
231: Other therapeutic procedures 518 (47) 575 (30) 5.24 (0.13) 4.84 (0.38) 2.31 (0.15) 1.94 (0.14)
152: Arthroplasty knee 481 (19) 510 (27) 3.89 (0.04) 3.93 (0.32) 0.12 (0.01) 0.19** (0.01)
54: Other vascular catheterization; not heart 462 (14) 456 (24) 9.38 (0.14) 9.56 (0.75) 8.40 (0.20) 8.40 (0.65)
84: Cholecystectomy and common duct exploration 390 (9) 383 (21) 4.65 (0.04) 4.78 (0.40) 0.75 (0.03) 0.54** (0.04)
153: Hip replacement; total and partial 365 (15) 387 (21) 4.96 (0.05) 5.12 (0.42) 0.98 (0.04) 1.16 (0.09)
219: Alcohol and drug rehabilitation/detoxification 358 (42) 325 (18) 5.04 (0.26) 5.34 (0.45) 0.11 (0.02) 0.01** (0.00)
133: Episiotomy 356 (19) 418* (23) 2.18 (0.01) 2.16 (0.19)) 0.00 (0.00) 0.00 (0.00)
48: Insertion; revision; replacement; removal of cardiac pacemaker or cardioverter/defibrillator 316 (13) 262* (16) 5.14 (0.07) 5.20 (0.46) 1.18 (0.04) 1.45* (0.12)
158: Spinal fusion 303 (15) 276 (16) 4.08 (0.08) 4.23 (0.37) 0.26 (0.02) 0.33* (0.02)
76: Colonoscopy and biopsy 301 (23) 280 (16) 5.03 (0.37) 5.46 (0.47) 0.87 (0.07) 1.21** (0.10)
80: Appendectomy 298 (7) 307 (18) 2.89 (0.03) 2.97 (0.27) 0.12 (0.01) 0.00** (0.00)
58: Hemodialysis 290 (9) 258 (15) 5.39 (0.06) 6.19 (0.54) 3.46 (0.10) 3.55 (0.30)
78: Colorectal resection 279 (8) 268 (16) 9.94 (0.08) 10.05 (0.85) 4.03 (0.11) 4.32 (0.37)
146: Treatment; fracture or dislocation of hip and femur 272 (6) 289 (17) 6.06 (0.06) 5.94 (0.51) 1.84 (0.06) 1.53* (0.12)

* Significant at a 5 percent level.
** Significant at a 1 percent level.
1 A significance test was not performed because a valid standard error was not available.
(a) Because of very small sample size, the NHDS estimate and standard error were unreliable and not reported.
(c) A valid standard error could not be calculated.

Table 13. NIS and MedPAR Comparisons by Overall, 2004
  Number of Discharges in Thousands (Standard Error) Percentage of Discharges (Standard Error) Average Length of Stay in Days (Standard Error) In-Hospital Mortality Rate Percent (Standard Error) Average Total Hospital charge (Standard Error)
NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR
U.S. 14,028 (285) 12,530** 0.00 (0.00) 0.001 5.79 (0.04) 5.77 3.99 (0.05) 3.80** $25,837 (531) $26,766
Region
Northeast 2,812 (141) 2,479* 20.04 (0.88) 19.78 6.60 (0.14) 6.47 4.75 (0.21) 4.27* $31,458 (1,790) $31,337
South 3,521 (142) 3,332 25.10 (0.88) 26.59 5.46 (0.07) 5.43 3.48 (0.07) 3.41 $20,640 (517) $22,020**
Midwest 5,565 (171) 5,053** 39.67 (0.98) 40.32 5.69 (0.06) 5.74 3.88 (0.06) 3.82 $23,562 (646) $24,401
West 2,129 (108) 1,665** 15.18 (0.71) 13.29** 5.49 (0.12) 5.50 4.14 (0.13) 3.85* $33,797 (1,637) $36,629

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.

Table 14. NIS and MedPAR Comparisons by Hospital Control, 2004
Control Number of Discharges in Thousands (Standard Error) Percentage of Discharges (Standard Error) Average Length of Stay in Days (Standard Error) In-Hospital Mortality Rate Percent (Standard Error) Average Total Hospital charge (Standard Error)
NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR
Total Public 1,781 (151) 1,429* 12.70 (1.10) 11.40 5.63 (0.12) 5.73 4.03 (0.11) 3.85 $20,166 (964) $22,186*
1-99 Beds 544 (38) 326** 30.53 (2.39) 22.85** 4.60 (0.08) 4.57 3.90 (0.09) 3.56** $10,649 (650) $11,125
100-199 Beds 343 (57) 303 19.28 (2.90) 21.23 5.33 (0.22) 5.48 4.26 (0.20 3.82* $18,217 (1,053) $17,823
200-299 Beds 225 (41) 193 12.63 (2.52) 13.56 5.90 (0.20) 5.84 3.93 (0.30) 3.89 $25,010 (2,562) $22,717
300-499 Beds 339 (89) 306 19.04 (4.78) 21.42 6.51 (0.29) 6.29 4.25 (0.44) 3.96 $28,515 (2,046) $29,200
500+ Beds 329 (92) 299 18.50 (4.90) 20.91 6.54 (0.38) 6.59 3.84 (0.30) 4.05 $26,003 (2,443) $31,174*
Total Private Non-Profit 10,357 (319) 9,388** 73.83 (1.41) 74.92 5.81 (0.05) 5.78 4.04 (0.07) 3.85** $25,868 (653) $26,216
1-99 Beds 1,162 (58) 879** 11.22 (0.61) 9.37** 4.71 (0.09) 4.69 3.74 (0.09) 3.53* $13,964 (608) $14,766
100-199 Beds 1,979 (120) 1,810 19.11 (1.16) 19.28 5.49 (0.08) 5.43 3.98 (0.10) 3.84 $21,652 (1,284) $20,564
200-299 Beds 1,972 (190) 1,913 19.03 (1.86) 20.37 5.94 (0.13) 5.75 4.24 (0.29) 3.83 $26,869 (1,830) $26,093
300-499 Beds 3,047 (280) 2,669 29.42 (2.59) 28.43 5.79 (0.10) 5.92 3.92 (0.11) 3.88 $25,475 (953) $27,823*
500+ Beds 2,196 (251) 2,114 21.20 (2.23) 22.52 6.60 (0.13) 6.38 4.26 (0.11) 3.98* $35,649 (1,698) $33,903
Total Proprietary 1,888 (129) 1,712 13.46 (0.89) 13.66 5.80 (0.12)) 5.76 3.67 (0.09) 3.50 $31,022 (1,498) $33,601
1-99 Beds 358 (40) 310 18.96 (2.21) 18.10 5.65 (0.38) 4.56** 3.52 (0.20) 2.83** $24,679 (1,749) $22,670
100-199 Beds 655 (50) 583 34.71 (2.73) 34.04 5.77 (0.16) 5.72 3.76 (0.13) 3.55 $29,563 (1,980) $29,869
200-299 Beds 393 (77) 398 20.81 (4.13) 23.26 5.85 (0.28) 6.05 3.81 (0.20) 3.79 $33,664 (4,630) $38,439
300-499 Beds 453 (102) 285 23.99 (4.83) 16.69 5.86 (0.09) 6.31** 3.54 (0.16) 3.57 $34,313 (2,686) $43,902**
500+ Beds 28 (28) 135** 1.51 (1.51) 7.88** 6.68 (0.00) 6.66** 3.67 (0.00) 3.851 $55,351 (0) $38,730**

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.

Table 15. NIS and MedPAR Comparisons by Hospital Control, 2004
Hospital Type Number of Discharges in Thousands (Standard Error) Percentage of Discharges (Standard Error) Average Length of Stay in Days (Standard Error) In-Hospital Mortality Rate Percent (Standard Error) Average Total Hospital charge (Standard Error)
NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR
Rural 2,420 (100) 1,964** 17.25 (0.67) 15.67* 4.83 (0.05) 4.97* 3.84 (0.07) 3.69* $14,133 (582) $14,763
small 595 (25) 277** 24.58 (1.37) 14.12** 4.19 (0.06) 4.05* 3.81 (0.11) 3.26** $9,336 (302) $9,895
medium 694 (60) 591 28.71 (2.77) 30.09 4.63 (0.08) 4.59 3.72 (0.10) 3.57 $13,231 (638) $13,057
large 1,130 (114) 1,095 46.70 (3.26) 55.78** 5.30 (0.09) 5.41 3.93 (0.12) 3.86 $17,211 (1,106) $16,914
Urban, Non-teaching 6,440 (174) 5,704** 45.91 (0.99) 45.52 5.79 (0.06) 5.69 3.97 (0.10) 3.76* $26,777 (778) $27,199
small 759 (51) 627* 11.79 (0.79) 11.00 5.47 (0.20) 4.91** 3.76 (0.13) 3.33** $20,595 (1,127) $20,343
medium 1,765 (92) 1,618 27.41 (1.42) 28.37 5.75 (0.10) 5.60 4.14 (0.10) 3.82** $25,600 (1,303) $24,599
large 3,915 (165) 3,458** 60.79 (1.50) 60.62 5.87 (0.08) 5.88 3.93 (0.15) 3.81 $28,529 (1,146) $29,660
Urban, Teaching 5,167 (202) 4,861 36.83 (1.05) 38.79 6.23 (0.08) 6.18 4.09 (0.07) 3.90* $30,310 (984) $31,108
small 597 (91) 618 11.56 (1.74) 12.72 6.06 (0.27) 5.92 3.82 (0.26) 3.78 $28,098 (3,620) $28,711
medium 1,360 (189) 1,308 26.33 (3.75) 26.91 5.96 (0.16) 6.04 4.09 (0.16) 3.92 $25,662 (1,360) $28,522*
large 3,208 (261) 2,934 62.09 (3.87) 60.35 6.38 (0.10) 6.31 4.14 (0.09) 3.91* $32,602 (1,283) $32,767

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.

Return to Contents

Table 16. NIS and MedPAR Comparisons by Patient Characteristics, 2004
  Number of Discharges in Thousands (Standard Error) Percentage of Discharges (Standard Error) Average Length of Stay in Days (Standard Error) In-Hospital Mortality Rate Percent (Standard Error) Average Total Hospital charge (Standard Error)
NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR
Age Group                    
0-64 Years 2,307 (54) 2,191* 16.44 (0.32) 17.48** 6.13 (0.06) 6.09 2.04 (0.04) 1.95* $24,990 (564) $26,380*
65-74 Years 4,210 (93) 3,766** 30.01 (0.18) 30.05 5.50 (0.04) 5.50 3.08 (0.05) 3.01 $27,845 (554) $28,962*
75-84 Years 4,978 (113) 4,253** 35.48 (0.20) 33.94** 5.83 (0.04) 5.79 4.35 (0.06) 4.11** $26,447 (577) $27,184
85+ Years 2,529 (58) 2,319** 18.02 (0.19) 18.50* 5.87 (0.04) 5.86 6.58 (0.09) 6.28** $22,097 (531) $22,797
Gender                    
Female 7,969 (161) 7,077** 56.81 (0.15) 56.48* 5.77 (0.04) 5.76 3.71 (0.05) 3.54** $24,350 (499) $25,129
Male 6,047 (127) 5,453** 43.10 (0.15) 43.51** 5.81 (0.04) 5.79 4.36 (0.06) 4.14** $27,805 (589) $28,891
Race                    
White 8,175 (313) 10,362** 58.27 (1.68) 82.69** 5.75 (0.05) 5.63* 4.11 (0.06) 3.84** $26,083 (608) $26,190
Black 1,253 (94) 1,537** 8.93 (0.63) 12.27** 6.86 (0.11) 6.55** 4.08 (0.12) 3.73** $27,859 (1,071) $28,043
Other 987 (75) 583** 7.03 (0.53) 4.65** 6.30 (0.11) 6.15 4.25 (0.12) 3.50** $34,989 (1,853) $33,672
Unknown 3,612 (258) 47** 25.75 (1.85) 0.37** 5.36 (0.07) 5.65** 3.63 (0.07) 2.97** $22,231 (1,067) $26,342**

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.

Table 17. NIS and MedPAR Comparisons by DRG, 2004
DRG Number of Discharges in Thousands (Standard Error) Percentage of Discharges (Standard Error) Average Length of Stay in Days (Standard Error) In-Hospital Mortality Rate Percent (Standard Error) Average Total Hospital charge (Standard Error)
NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR
127: HEART FAILURE & SHOCK 775 (17) 673** 5.53 (0.06) 5.37* 5.06 (0.04) 5.11 4.06 (0.07) 3.97 $18,394 (477) $18,629
89: SIMPLE PNEUMONIA & PLEURISY AGE >17 W CC 589 (11) 495** 4.20 (0.05) 3.95** 5.57 (0.04) 5.62 4.81 (0.09) 4.61* $18,141 (431) $18,461
209: MAJOR JOINT & LIMB REATTACHMENT PROCEDURES OF LOWER EXTREMITY 495 (19) 464 3.53 (0.11) 3.70 4.57 (0.04) 4.52 0.69 (0.03) 0.66 $35,082 (642) $34,820
88: CHRONIC OBSTRUCTIVE PULMONARY DISEASE 433 (9) 378** 3.08 (0.04) 3.02 4.82 (0.03) 4.85 1.54 (0.05) 1.43* $15,585 (378) $15,823
430: PSYCHOSES 356 (21) 340 2.54 (0.15) 2.71 10.48 (0.29) 10.60 0.08 (0.01) 0.09 $17,630 (800) $17,514
462: REHABILITATION 334 (22) 308 2.38 (0.15) 2.46 12.01 (0.19) 11.72 0.61 (0.07) 0.22** $24,446 (1,189) $24,058
182: ESOPHAGITIS 327 (7) 287** 2.33 (0.02) 2.29 4.37 (0.03) 4.41 1.23 (0.04) 1.29 $14,886 (337) $15,266
174: G.I. HEMORRHAGE W CC 302 (6) 262** 2.15 (0.02) 2.09** 4.64 (0.03) 4.67 2.92 (0.07) 2.98 $18,123 (385) $18,279
296: NUTRITIONAL & MISC METABOLIC DISORDERS AGE >17 W CC 283 (6) 245** 2.01 (0.02) 1.96* 4.69 (0.04) 4.70 3.38 (0.09) 3.45 $14,626 (376) $14,749
416: SEPTICEMIA AGE >17 282 (7) 245** 2.01 (0.04) 1.95 7.42 (0.07) 7.43 20.19 (0.30) 19.89 $30,758 (851) $31,003
143: CHEST PAIN 278 (8) 247** 1.98 (0.04) 1.97 2.08 (0.02) 2.09 0.11 (0.01) 0.11 $10,250 (257) $10,340
14: SPECIFIC CEREBROVASCULAR DISORDERS EXCEPT TIA 276 (6) 243** 1.97 (0.02) 1.94 5.55 (0.04) 5.61 11.31 (0.20) 11.24 $21,974 (509) $22,385
320: KIDNEY & URINARY TRACT INFECTIONS AGE >17 W CC 250 (5) 213** 1.78 (0.02) 1.70** 5.02 (0.04) 5.04 2.18 (0.07) 2.05 $15,150 (368) $15,573
138: CARDIAC ARRHYTHMIA & CONDUCTION DISORDERS W CC 237 (5) 202** 1.69 (0.02) 1.61** 3.85 (0.03) 3.89 2.64 (0.08) 2.59 $14,897 (402) $14,857
527 210 (15) 213 1.50 (0.09) 1.70* 2.29 (0.05) 2.22 0.27 (0.02) 0.27 $42,981 (1,509) $41,617
316: RENAL FAILURE 209 (6) 183** 1.49 (0.02) 1.46 6.28 (0.05) 6.26 7.62 (0.17) 7.52 $22,434 (573) $22,861
79: RESPIRATORY INFECTIONS & INFLAMMATIONS AGE >17 W CC 185 (4) 157** 1.32 (0.02) 1.25* 8.13 (0.07) 8.15 12.44 (0.23) 12.15 $27,647 (745) $28,317
121: CIRCULATORY DISORDERS W AMI & MAJOR COMP 177 (4) 150** 1.26 (0.02) 1.20** 6.07 (0.05) 6.24** 0.00 (0.00) 0.001 $27,594 (751) $27,757
148: MAJOR SMALL & LARGE BOWEL PROCEDURES W CC 147 (3) 133** 1.05 (0.01) 1.06 11.99 (0.09) 12.06 7.55 (0.17) 7.53 $59,889 (1,226) $60,660
210: HIP & FEMUR PROCEDURES EXCEPT MAJOR JOINT AGE >17 W CC 140 (3) 126** 1.00 (0.01) 1.00 6.60 (0.05) 6.66 2.75 (0.10) 2.68 $32,183 (625) $32,282
141: SYNCOPE & COLLAPSE W CC 138 (4) 120** 0.98 (0.01) 0.96 3.43 (0.04) 3.44 0.42 (0.04) 0.45 $13,746 (413) $13,837
395: RED BLOOD CELL DISORDERS AGE >17 132 (3) 112** 0.94 (0.01) 0.90* 4.06 (0.06) 4.27** 1.29 (0.07) 1.39 $14,785 (422) $15,563
132: ATHEROSCLEROSIS W CC 131 (4) 109** 0.93 (0.02) 0.87* 2.76 (0.03) 2.78 0.72 (0.05) 0.68 $11,298 (353) $11,425
124: CIRCULATORY DISORDERS EXCEPT AMI 130 (5) 128 0.93 (0.02) 1.02** 4.43 (0.06) 4.36 1.04 (0.07) 0.97 $26,500 (708) $26,013
524: TRANSIENT ISCHEMIA 128 (3) 113** 0.91 (0.01) 0.90 3.12 (0.03) 3.15 0.23 (0.03) 0.23 $13,134 (351) $13,281

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.

Table 18. NIS and MedPAR Comparisons by Principal Diagnosis, 2004
Principal Diagnosis Number of Discharges in Thousands (Standard Error) Percentage of Discharges (Standard Error) Average Length of Stay in Days (Standard Error) In-Hospital Mortality Rate Percent (Standard Error) Average Total Hospital charge (Standard Error)
NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR
108: Congestive heart failure; nonhypertensive 839 (19) 733** 5.98 (0.06) 5.85* 5.53 (0.05) 5.59 4.32 (0.07) 4.28 $24,995 (676) $25,960
122: Pneumonia (except that caused by tuberculosis or sexually transmitted disease) 736 (14) 620** 5.25 (0.07) 4.95** 6.29 (0.05) 6.36 6.29 (0.09) 6.10 $22,591 (558) $23,367
101: Coronary atherosclerosis and other heart disease 654 (28) 612 4.66 (0.15) 4.88 3.75 (0.05) 3.72 0.81 (0.03) 0.83 $37,904 (1,262) $38,804
106: Cardiac dysrhythmias 462 (12) 408** 3.29 (0.04) 3.25 3.86 (0.03) 3.87 1.45 (0.04) 1.37 $24,551 (659) $25,159
100: Acute myocardial infarction 407 (12) 359** 2.90 (0.05) 2.86 5.99 (0.07) 6.03 9.75 (0.16) 9.70 $43,845 (1,342) $44,817
127: Chronic obstructive pulmonary disease and bronchiectasis 394 (8) 344** 2.81 (0.04) 2.74 5.10 (0.04) 5.16 2.46 (0.07) 2.34 $17,648 (444) $18,221
203: Osteoarthritis 390 (16) 364 2.78 (0.10) 2.90 3.97 (0.05) 3.92 0.19 (0.01) 0.17 $32,700 (629) $32,568
109: Acute cerebrovascular disease 360 (8) 315** 2.56 (0.03) 2.51 6.02 (0.06) 6.13 10.94 (0.19) 10.74 $25,693 (650) $26,809
237: Complication of device; implant or graft 342 (11) 324 2.43 (0.05) 2.59** 6.09 (0.07) 5.96 2.28 (0.06) 2.22 $37,238 (829) $38,497
254: Rehabilitation care; fitting of prostheses; and adjustment of devices 338 (23) 312 2.41 (0.16) 2.49 12.10 (0.19) 11.80 0.61 (0.07) 0.22** $24,763 (1,214) $24,393
102: Nonspecific chest pain 324 (9) 295** 2.31 (0.04) 2.36 2.18 (0.02) 2.20 0.11 (0.01) 0.11 $11,618 (267) $11,892
2: Septicemia (except in labor) 312 (8) 272** 2.22 (0.04) 2.17 8.55 (0.09) 8.64 19.76 (0.29) 19.42 $37,733 (1,059) $39,143
55: Fluid and electrolyte disorders 310 (6) 269** 2.21 (0.02) 2.15* 4.44 (0.03) 4.53* 2.92 (0.08) 3.04 $14,336 (375) $14,667
159: Urinary tract infections 299 (6) 255** 2.13 (0.03) 2.04** 5.02 (0.04) 5.08 1.99 (0.06) 1.87 $15,556 (377) $16,191
226: Fracture of neck of femur (hip) 252 (6) 223** 1.80 (0.02) 1.78 6.42 (0.05) 6.36 3.20 (0.08) 3.14 $31,099 (590) $31,499
205: Spondylosis; intervertebral disc disorders; other back problems 218 (7) 214 1.55 (0.04) 1.71** 4.04 (0.05) 3.88** 0.41 (0.03) 0.34* $26,326 (720) $26,763
153: Gastrointestinal hemorrhage 216 (4) 189** 1.54 (0.01) 1.51 4.91 (0.04) 4.96 4.16 (0.10) 4.16 $20,521 (448) $20,909
50: Diabetes mellitus with complications 214 (5) 189** 1.52 (0.02) 1.51 6.30 (0.07) 6.27 1.75 (0.06) 1.69 $24,313 (658) $25,530
238: Complications of surgical procedures or medical care 198 (5) 178** 1.41 (0.02) 1.42 6.99 (0.07) 6.79* 2.31 (0.08) 2.28 $28,609 (658) $29,460
69: Affective disorders 183 (10) 180 1.30 (0.07) 1.44 9.54 (0.23) 9.69 0.06 (0.01) 0.09* $16,620 (810) $16,374
197: Skin and subcutaneous tissue infections 182 (4) 160** 1.30 (0.01) 1.28 5.58 (0.05) 5.52 0.89 (0.05) 0.82 $16,507 (414) $16,819
157: Acute and unspecified renal failure 178 (5) 153** 1.27 (0.02) 1.22 7.10 (0.07) 7.17 8.30 (0.18) 8.45 $26,485 (733) $27,453
131: Respiratory failure; insufficiency; arrest (adult) 174 (5) 152** 1.24 (0.03) 1.21 10.03 (0.22) 9.56* 21.56 (0.39) 21.56 $50,303 (1,584) $50,615
145: Intestinal obstruction without hernia 170 (3) 150** 1.21 (0.01) 1.20 6.84 (0.05) 6.89 4.20 (0.11) 4.30 $26,711 (592) $27,286
146: Diverticulosis and diverticulitis 168 (4) 146** 1.20 (0.01) 1.17 5.57 (0.05) 5.69* 1.68 (0.07) 1.71 $23,176 (511) $23,930

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.

Table 19. NIS and MedPAR Comparisons by Principal Procedure, 2004
Principal Procedure Number of Discharges in Thousands (Standard Error) Percentage of Discharges (Standard Error) Average Length of Stay in Days (Standard Error) In-Hospital Mortality Rate Percent (Standard Error) Average Total Hospital Charge (Standard Error)
NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR NIS MedPAR
70: Upper gastrointestinal endoscopy; biopsy 409 (11) 365** 2.91 (0.04) 2.91 5.82 (0.07) 5.93 1.90 (0.05) 1.87 $22,561 (561) $22,831
45: Percutaneous transluminal coronary angioplasty (PTCA) 366 (23) 365 2.61 (0.14) 2.91* 3.07 (0.06) 3.00 1.10 (0.05) 1.09 $45,230 (1,450) $43,984
222: Blood transfusion 361 (13) 290** 2.57 (0.08) 2.31** 5.83 (0.06) 5.92 5.75 (0.13) 5.97 $21,299 (556) $22,011
47: Diagnostic cardiac catheterization; coronary arteriography 316 (13) 310 2.25 (0.06) 2.47** 4.16 (0.06) 4.12 1.36 (0.05) 1.30 $26,566 (687) $25,958
216: Respiratory intubation and mechanical ventilation 297 (7) 253** 2.12 (0.03) 2.02* 9.26 (0.12) 9.00* 37.46 (0.41) 38.13 $52,861 (1,427) $53,537
152: Arthroplasty knee 280 (11) 266 1.99 (0.07) 2.12 4.02 (0.05) 3.99 0.18 (0.01) 0.17 $34,137 (664) $33,834
48: Insertion; revision; replacement; removal of cardiac pacemaker or cardioverter/defibrillator 241 (10) 226 1.72 (0.05) 1.80 5.17 (0.08) 5.04 1.31 (0.05) 1.29 $62,568 (2,192) $62,118
153: Hip replacement; total and partial 237 (9) 218* 1.69 (0.05) 1.74 5.36 (0.05) 5.31 1.35 (0.06) 1.33 $37,796 (701) $37,810
54: Other vascular catheterization; not heart 230 (7) 214 1.63 (0.04) 1.71 9.11 (0.10) 8.93 11.87 (0.26) 11.77 $34,951 (776) $35,602
58: Hemodialysis 217 (7) 200* 1.55 (0.04) 1.59 5.49 (0.07) 5.33* 3.70 (0.11) 3.52 $21,889 (661) $21,882
146: Treatment; fracture or dislocation of hip and femur 180 (4) 163** 1.28 (0.01) 1.30 6.20 (0.05) 6.27 2.38 (0.08) 2.34 $30,173 (586) $30,382
76: Colonoscopy and biopsy 167 (7) 141** 1.19 (0.04) 1.12 5.78 (0.16) 6.00 1.27 (0.07) 1.34 $21,006 (798) $21,642
61: Other OR procedures on vessels other than head and neck 163 (6) 154 1.16 (0.03) 1.23 7.22 (0.14) 7.15 4.58 (0.15) 4.43 $47,118 (1,187) $48,160
231: Other therapeutic procedures 161 (18) 145 1.15 (0.13) 1.16 5.71 (0.23) 5.51 5.39 (0.27) 5.34 $21,008 (1,444) $20,647
78: Colorectal resection 142 (3) 128** 1.01 (0.01) 1.02 10.97 (0.09) 11.00 6.37 (0.17) 6.16 $55,163 (1,155) $55,976
44: Coronary artery bypass graft (CABG) 132 (8) 126 0.94 (0.05) 1.01 9.99 (0.12) 9.71* 3.14 (0.14) 3.13 $90,538 (2,945) $90,111
84: Cholecystectomy and common duct exploration 132 (3) 121** 0.94 (0.01) 0.97* 6.26 (0.06) 6.39 1.67 (0.08) 1.78 $33,938 (695) $34,377
193: Diagnostic ultrasound of heart (echocardiogram) 131 (13) 108 0.93 (0.09) 0.86 5.21 (0.09) 5.41* 2.28 (0.16) 2.44 $20,570 (1,321) $20,891
169: Debridement of wound; infection or burn 109 (3) 96** 0.77 (0.01) 0.76 11.38 (0.22) 10.71** 4.27 (0.17) 4.05 $41,242 (1,169) $41,780
39: Incision of pleura; thoracentesis; chest drainage 100 (2) 92** 0.71 (0.01) 0.73* 8.07 (0.07) 8.18 7.83 (0.20) 7.95 $30,177 (777) $30,665
213: Physical therapy exercises; manipulation; and other procedures 99 (14) 101 0.71 (0.10) 0.80 12.25 (0.43) 10.89** 0.88 (0.15) 0.36** $28,990 (2,667) $25,017
51: Endarterectomy; vessel of head and neck 87 (3) 86 0.62 (0.02) 0.68** 2.85 (0.07) 2.85 0.49 (0.05) 0.43 $22,346 (555) $22,833
37: Diagnostic bronchoscopy and biopsy of bronchus 86 (3) 81 0.61 (0.01) 0.64 9.23 (0.10) 9.24 6.19 (0.21) 6.31 $38,673 (1,105) $38,774
3: Laminectomy; excision intervertebral disc 82 (4) 87 0.58 (0.02) 0.69** 3.54 (0.07) 3.39* 0.33 (0.04) 0.30 $22,641 (714) $21,771
177: Computerized axial tomography (CT) scan head 80 (12) 58 0.57 (0.08) 0.46 4.96 (0.17) 4.98 4.15 (0.25) 4.21 $20,077 (2,041) $19,805

*Significant at a 5 percent level.
**Significant at a 1 percent level.
1A significance test was not performed because a valid standard error was not available.

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Internet Citation: HCUP NIS 2004 NIS Comparison Report. Healthcare Cost and Utilization Project (HCUP). May 2016. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/db/nation/nis/reports/2004niscomparisonrpt.jsp.
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