Clinical Classifications for Health Policy Research, Version 2: Hospital Inpatient Statistics, 1992

Below is a summary of HCUP-3 Research Note 1 (AHCPR Pub. No. 96-0017), which is available from the AHCPR Publications Clearinghouse. Call toll free 800-358-9295.


This publication describes Version 2 of the Clinical Classifications for Health Policy Research (CCHPR), a diagnosis and procedure categorization scheme, and provides descriptive statistics for 1992 hospital inpatient stays illustrating the use of CCHPR categories. Diagnoses and procedures for hospital stays are coded using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM), a uniform and standardized coding system. ICD-9-CM consists of over 12,000 diagnosis codes and 3,500 procedure codes. Although it is possible to present descriptive statistics for individual ICD-9-CM codes, it is often helpful to aggregate codes into clinically meaningful categories that comprise similar conditions or procedures. Electronic versions of CCHPR classification schemes are available in Clinical Classifications for Health Policy Research, Version 2: Software and User's Guide.

Development of CCHPR

CCHPR Version 1 was the initial endeavor to construct such clinically meaningful categories. CCHPR Version 2 is based on the Version 1 summary diagnosis and procedure categories. The original categories were modified on the basis of clinical homogeneity, number of discharges, and ICD-9-CM coding changes.

After CCHPR Version 2 was completed, expanded hierarchical systems for both diagnoses and procedures were constructed by aggregating CCHPR codes into larger groupings and disaggregating them into smaller groupings of one or more individual ICD-9-CM codes. A four-level system was developed for diagnoses and a three-level system was developed for procedures.

How Can CCHPR Be Used?

CCHPR categories can be employed in many types of projects analyzing data on diagnoses and procedures. For example, they can be used to identify populations for disease- or procedure-specific studies; provide statistical information (such as charges and length of stay) about relatively specific conditions; define comorbidities; and cross-classify procedures by diagnoses to provide insight into the variety of procedures performed for particular diagnoses. Diagnosis and Procedure Combinations in Hospital Inpatient Data shows the most common diagnoses and procedures for hospital inpatients in 1992, using CCHPR coding.

Source of Data

The statistics presented in this report are based on data on hospital inpatient stays from the Healthcare Cost and Utilization Project (HCUP-3) Nationwide Inpatient Sample (NIS) Release 1, which contains discharge-level clinical and resource use information included in a typical discharge abstract. NIS Release 1 includes nearly 900 hospitals from 11 States (Arizona, California, Colorado, Florida, Illinois, Iowa, Massachusetts, New Jersey, Pennsylvania, Washington, and Wisconsin) and 6 million discharges per year, and spans the years 1988-92.

A 20-percent sample of NIS discharges for 1992 was used for this study (N = 1,239,148). These discharges were weighted to obtain estimates that are representative of hospital inpatient discharges in the United States. The estimated total number of discharges represented in these analyses is 34,989,827.

For all analyses, only the principal diagnosis and principal procedure were used. The statistics include:

Using the Tables

In general, the diagnosis and procedure categories listed in the tables and appendices follow the order determined by the ICD-9-CM system. For the most part, chapter headings have been maintained and the individual categories are arranged by numeric ICD-9-CM code.

The approach to finding a specific condition or procedure will vary depending on the information desired. To locate a general condition, body system, or procedure, one approach is to scan the major headings provided as a table of contents in front of each table. Then go to that section of the table and browse through the specific categories until the appropriate condition or procedure is found.

To locate a particular ICD-9-CM code, go directly to the appendices. The categories are arranged by the first-listed ICD-9-CM code in the grouping. Scan the column of codes in the appendices to the appropriate location. Identify the corresponding category number and go to that category number in the table.

For More Information About CCHPR

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Current as of December 1998

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