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NIS Description of Data Elements
The NIS is a set of longitudinal hospital inpatient databases included in the HCUP family. These databases are created by AHRQ through a Federal-State-Industry partnership.
 
 
National (Nationwide) Inpatient Sample (NIS)
is the largest all-payer inpatient care database in the United States, containing data on more than seven million hospital stays. Its large sample size is ideal for developing national and regional estimates and enables analyses of rare conditions, uncommon treatments, and special populations. The following links provide data elements descriptions for the NIS.

Data element descriptions explain how the data element is coded in the HCUP databases, what the uniform values are, and State-specific coding practices. The descriptions are cumulative across all states and years of NIS data from 1988 to the current data year. Not all data elements in the NIS are uniformly coded across states. Please check the "State Specific Notes" section for each data element before analysis. In addition, not all data elements in the NIS are available from every state. Refer to the year-specific Introduction to the National (Nationwide) Inpatient Sample for information on which States and data elements are included in each year of the NIS. Not all data elements are available each year. Please check the Availability of Data Elements by year table.

For a description of how HCUP data elements are coded, restriction on use, uniform values, and state-specific coding practices, check the corresponding boxes below and then click the "View Description of Data Elements".

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NIS Core Data Elements NIS Hospital File Data Elements NIS Severity File Data Elements NIS Diagnosis and Procedure Groups File
ADAYWK
AGE
AGEDAY
AGE_NEONATE
AMONTH
ASOURCE
ASOURCEUB92
ASOURCE_X
ATYPE
AWEEKEND
D10CWT_U
DCCHPRn
DIED
DISCWT
DISCWT_U
DISCWT10
DISCWTcharge
DISCWTcharge10
DISP
DISPUB04
DISPUB92
DISPUniform
DQTR
DQTR_X
DRG_NoPOA
DRG
DRG10
DRG18
DRG24
DRGVER
DSHOSPID
DSNDX
DSNPR
DSNUM
DSTYPE
DXn
DXCCSn
DXSYS
DXVn
ECODEn
E_CCSn
ELECTIVE
FEMALE
HCUP_ED
HOSPBRTH
HOSPID
HOSPST
HOSP_DIVISION
HOSP_NIS
HOSPSTCO
KEY
KEY_NIS
LOS
LOS_X
MDC
MDC10
MDC18
MDC24
MDC_NoPOA
MDID_S
MDNUM1_R
MDNUM1_S
MDNUM2_R
MDNUM2_S
NCHRONIC
NDX
NEOMAT
NECODE
NIS_STRATUM
NPR
ORPROC
PAY1
PAY1_N
PAY1_X
PAY2
PAY2_N
PAY2_X
PCCHPRn
PL_NCHS2006
PL_UR_CAT4
PointOfOriginUB04
PointOfOrigin_X
PRn
PRCCSn
PRDAYn
PROCESS
PRSYS
PRVn
RACE
SEQ
SEQ_SID
SEX
SURGID_S
TOTCHG
TOTCHG_X
TRAN_IN
TRAN_OUT
YEAR
ZIPINC
ZIPINC_QRTL
ZIPINC4
ZIPINC8
AHAID
DISCWT
DISCWT_F
DISCWT_S
DISCWT_U
DISCWTcharge
H_BEDSZ
H_CONTRL
H_LOC
H_LOCTCH
H_REGION
H_TCH
HFIPSSTCO
HOSP_BEDSIZE
HOSP_CONTROL
HOSP_LOCATION
HOSP_LOCTEACH
HOSP_LPNFTEAPD
HOSP_MHSCLUSTER
HOSP_MHSMEMBER
HOSP_NAFTEAPD
HOSP_DIVISION
HOSP_NIS
HOSP_OPSURGPCT
HOSP_REGION
HOSP_RNFTEAPD
HOSP_RNPCT
HOSP_TEACH
HOSPADDR
HOSPCITY
HOSPID
HOSPNAME
HOSPST
HOSPSTCO
HOSPWT
HOSPWT_F
HOSPWT_S
HOSPWT_U
HOSPZIP
IDNUMBER
LOCTEACH
N_DISC_F
N_DISC_S
N_DISC_U
N_HOSP_F
N_HOSP_S
N_HOSP_U
NIS_STRATUM
S_DISC_S
S_DISC_U
S_HOSP_S
S_HOSP_U
ST_BEDSZ
ST_OWNER
ST_REG
STRAT_ST
STRATUM
TOTAL_DISC
TOTDSCHG
YEAR
APRDRG
APRDRG_Risk_Mortality
APRDRG_Severity
APSDRG
APSDRG_Charge_Weight
APSDRG_LOS_Weight
APSDRG_Mortality_Weight
CM_AIDS
CM_ALCOHOL
CM_ANEMDEF
CM_ARTH
CM_BLDLOSS
CM_CHF
CM_CHRNLUNG
CM_COAG
CM_DEPRESS
CM_DM
CM_DMCX
CM_DRUG
CM_HTN_C
CM_HYPOTHY
CM_LIVER
CM_LYMPH
CM_LYTES
CM_METS
CM_NEURO
CM_OBESE
CM_PARA
CM_PERIVASC
CM_PSYCH
CM_PULMCIRC
CM_RENLFAIL
CM_TUMOR
CM_ULCER
CM_VALVE
CM_WGHTLOSS
DS_DX_Category1
DS_Stage1
DS_LOS_level
DS_LOS_Scale
DS_Mrt_Level
DS_Mrt_Scale
DS_RD_Level
DS_RD_Scale
HOSP_NIS
HOSPID
KEY KEY_NIS
CCSMGNn
CCSMSPn
CHRONn
CHRONBn
DXMCCSn
ECCSMGNn
E_MCCSn
HOSPID
HOSP_NIS
KEY
KEY_NIS
PCLASSn
PRMCCSn
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Internet Citation: HCUP NIS Description of Data Elements. Healthcare Cost and Utilization Project (HCUP). June 2014. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/db/nation/nis/nisdde.jsp.
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Last modified 6/24/14