hus14

Classification of Diseases, 9th Revision, Clinical Modification
(ICD–9–CM).
National Hospital Discharge Survey (NHDS)—In NHDS, up
to four different procedures are coded per hospital stay;
in 2010 data, up to eight different procedures are coded.
Common procedures were identified by procedure code
or, where appropriate, by groups of procedure codes
(Table XI). Procedures per hospital stay can be counted in
different ways depending on the type of data of interest.
Counting any-listed procedures means that if one or
more of the same procedure occurs during the hospital
stay, it is only counted once, so any-listed counts will
generally be equivalent to the number of hospital stays
during which a procedure was performed. Counting
all-listed procedures means that if the same procedure
occurs multiple times during a hospital stay it is counted
each time it occurs, up to the maximum of four available
codes, to maintain consistency across all of the data years
shown in Health, United States; thus, all-listed procedure
counts can be greater than the number of hospital stays
with a procedure. In Health, United States, NHDS
procedure data are presented for any-listed procedures.
Healthcare Cost and Utilization Project, National
(Nationwide) Inpatient Sample (HCUP–NIS)—Up to 15
procedures are coded per hospital stay in the HCUP–NIS
database. For each record, a principal procedure is
identified as the first procedure listed. HCUP–NIS
procedure data presented in Health, United States are
limited to operating room procedures that are principal
procedures (first-listed). Valid operating room procedures
were identified according to diagnosis-related groups
(DRGs) software. For DRG development, physician panels
classify all ICD–9–CM procedure codes based on whether
the procedure would be performed in operating rooms
in most hospitals. Clinical Classifications Software (CCS)
was used to categorize ICD–9–CM principal operating
room procedure codes into one of 231 clinically
meaningful categories. CCS was developed at the
Agency for Healthcare Research and Quality as a tool for
clustering patient procedures into a manageable number
of clinically meaningful categories. For more information
on CCS, see: http://www.hcup-us.ahrq.gov/
toolssoftware/ccs/AppendixBSinglePR.txt.The topranking
operating room procedure categories by age
group, based on the number of discharges and total
national costs, are presented in Health, United States
(Table XII). CCS categories labeled ‘‘other’’ are not
presented because these comprise miscellaneous
procedures that do not form a homogenous group.
(Also see Appendix II, Outpatient surgery.)
Proprietary hospital—See Appendix II, Hospital.
Public expenditures—See Appendix II, Health
expenditures, national.
Purchasing power parities (PPPs)—PPPs are calculated
rates of currency conversion that equalize the purchasing
power of different currencies by eliminating the differences
in price levels between countries. PPPs show the ratio of
prices in national currencies for the same good or service in
different countries. PPPs can be used to make intercountry
comparisons of the gross domestic product (GDP) and its
component expenditures. (Also see Appendix II, Gross
domestic product [GDP].)
Race—In 1977, the Office of Management and Budget
(OMB) issued ‘‘Race and Ethnic Standards for Federal
Statistics and Administrative Reporting’’ (Statistical Policy
Directive 15) to promote comparability of data among
federal data systems. The 1977 Standards called for the
federal government's data systems to classify individuals
into the following four racial groups: American Indian or
Alaska Native, Asian or Pacific Islander, black, and white.
Depending on the data source, the classification by race was
based on self-classification or on observation by an
interviewer or other person filling out the questionnaire.
In 1997, revisions were announced for classification of
individuals by race within the federal government's data
systems. (See: Revisions to the Standards for the
Classification of Federal Data on Race and Ethnicity. Fed
Regist 1997 October 30;62(210):58781–90.) The 1997
Standards specify five racial groups: American Indian or
Alaska Native, Asian, black or African American, Native
Hawaiian or Other Pacific Islander, and white. These five
categories are the minimum set for data on race in federal
statistics. The 1997 Standards also offer an opportunity for
respondents to select more than one of the five groups,
leading to many possible multiple-race categories. As with
the single-race groups, data for the multiple-race groups are
to be reported when estimates meet agency requirements
for reliability and confidentiality. The 1997 Standards allow
for observer or proxy identification of race but clearly state a
preference for self-classification. The federal government
considers race and Hispanic origin to be two separate and
distinct concepts. Thus, Hispanic persons may be of any race.
Federal data systems were required to comply with the 1997
Standards by 2003.
National Health Interview Survey (NHIS)—Starting with
Health, United States, 2002, race-specific estimates based
on NHIS were tabulated using the 1997 Standards for
data year 1999 and beyond and are not strictly
comparable with estimates for earlier years. The 1997
Standards specify five single-race categories plus
multiple-race categories. Estimates for specific race
groups are shown when they meet requirements for
statistical reliability and confidentiality. The race
categories white only, black or African American only,
American Indian or Alaska Native only, Asian only, and
Native Hawaiian or Other Pacific Islander only include
persons who reported only one racial group; the
category 2 or more races includes persons who reported
more than one of the five racial groups in the 1997
436 Appendix II. Definitions and Methods Health, United States, 2014