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NIS Description of Data Elements
The NIS is set of longitudinal hospital inpatient databases included in the HCUP family. These databases are created by AHRQ through a Federal-State-Industry partnership.
 
ZIPINC_QRTL - Median household income for patient's ZIP Code (based on current year)
 
Documentation Sections:
General Notes
Uniform Values
State Specific Notes
General Notes
 

This categorical variable (ZIPINC_QRTL) provides a quartile classification of the estimated median household income of residents in the patient's ZIP Code. The quartiles are identified by values of 1 to 4, indicating the poorest to wealthiest populations. These values are derived from ZIP Code-demographic data obtained from Claritas. Because these estimates are updated annually, the value ranges for the ZIPINC_QRTL categories vary by year. The dollar ranges represented by each category are:

Quartile Ranges of ZIPINC_QRTL by Year
Year Quartile 1 Quartile 2 Quartile 3 Quartile 4
1997 1-28,999 29,000-35,999 36,000-46,999 47,000+
1998 1-28,999 29,000-36,999 37,000-49,999 50,000+
1999 1-30,999 31,000-39,999 40,000-51,999 52,000+
2000 1-31,999 32,000-41,999 42,000-54,999 55,000+
2001 1-33,999 34,000-43,999 44,000-58,999 59,000+
2002 1-35,999 36,000-45,999 46,000-61,999 62,000+
2003 1-35,999 36,000-44,999 45,000-59,999 60,000+
2004 1-35,999 36,000-44,999 45,000 - 58,999 59,000+
2005 1-36,999 37,000-45,999 46,000-60,999 61,000+
2006 1 - 37,999 38,000 - 46,999 47,000 - 61,999 62,000+
2007 1 - 38,999 39,000 - 47,999 48,000 - 62,999 63,000+
2008 1 - 38,999 39,000 - 48,999 49,000 - 63,999 64,000+
2009 1 - 39,999 40,000 - 49,999 50,000 - 65,999 66,000+
2010 1 - 40,999 41,000 - 50,999 51,000 - 66,999 67,000+
2011 1 - 38,999 39,000 - 47,999 48,000 - 63,999 64,000+
2012 1 - 38,999 39,000 - 47,999 48,000 - 62,999 63,000+
2013 1 - 37,999 38,000 - 47,999 48,000 - 63,999 64,000+
2014 1 - 39,999 40,000 - 50,999 51,000 - 65,999 66,000+
2015 1 - 41,999 42,000 - 51,999 52,000 - 67,999 68,000+
2016 1 - 42,999 43,000 - 53,999 54,000 - 70,999 71,000+

Availability of information on the NIS for the median household income of the patient's ZIP Code:

  • Starting in 2003, ZIPINC_QRTL is available.
  • For the years 1998-2002, another categorical variable (ZIPINC) indicates the median household income of the patient's ZIP Code of residence based on 1999 demographics. The categories are defined so that the maximum for category 1 ($25,000) is approximately 150% of the 1999 poverty level and the boundary between the second and third categories ($35,000) is approximately the national median household income.
  • Prior to 1998, information on the median household income for a patient's ZIP Code was retained in two data elements ZIPINC4 and ZIPINC8.

To protect patient confidentiality, precautions are taken to mask ZIP Codes. ZIPINC_QRTL values have been suppressed for all ZIP Codes with populations below a minimum threshold. Also, when only one ZIP Code in a state was represented in a particular ZIPINC_QRTL category, ZIPINC_QRTL was set to missing (.). ZIPINC_QRTL is also reported as missing when the patient's ZIP Code was not reported, or it could not be matched to the Claritas file.

 
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Uniform Values
VariableDescriptionValueValue Description
ZIPINC_QRTLMedian household income for patient's ZIP Code (based on current year)10-25th percentile
226th to 50th percentile (median)
351st to 75th percentile
476th to 100th percentile
.Other (includes ZIP equal blank A, C, M, F and B)
 
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State Specific Notes
None
 
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Internet Citation: HCUP NIS Description of Data Elements. Healthcare Cost and Utilization Project (HCUP). September 2008. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/db/vars/zipinc_qrtl/nisnote.jsp.
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Last modified 9/17/08