Medicare Inpatient File, LDS or RIF: Counting Distinct Hospitalizations

Medicare Inpatient File, LDS or RIF: Counting Distinct Hospitalizations

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The base segment of the Medicare Inpatient claims files (RIF and LDS) contains a record for each claim submitted by a hospital (facility) during a patient’s hospitalization. More than 99% of the inpatient stays generate only one facility claim[1],[2].  However, for those stays that generate multiple facility claims, ResDAC recommends researchers follow CMS’s method to group distinct hospitalizations[3], which is used to create the MedPAR file.  They group claims by each unique combination of three elements:

1)       Patient identifier

  • "Encrypted CCW Beneficiary ID" (BENE_ID) in Identifiable files


  • “DESY SORT KEY” (DSYSRTKY) in Limited Data Set (LDS) files

2)       Admission date

  • “Claim Admission Date” (CLM_ADMSN_DT or ADMSN_DT) in RIF and 2009 and forward LDS files [prior to 2009, LDS files contained QQYY only, so this was not possible]

3)       Provider Number (aka CMS Certification Number [CCN])

  • “Provider Number” (PRVDR_NUM or PROVIDER) in both Identifiable and LDS files

RIF claims within a hospitalization may be sequenced by Claim From Date (CLM_FROM_DT or FROM_DT) and Claim Through Date (CLM_THRU_DT or THRU_DT), and within 2009 and forward LDS claims by Claim Through Date. In the last claim submitted, Claim Through Date will equal Discharge Date (NCH_BENE_DSCHRG_DT or DSCHRGDT).  

[1]Based on STAY_FINL_ACTN_CLM_CNT variable for inpatient stays in the 2011-2012 5% RIF MedPAR file.

[2]Multiple claims may be submitted by physicians, but those will be found in the Carrier claims data, not the IP claims data.

[3]MEDPAR2000_DD_20141022.pdf from Data Administration page of    Accessed January 22, 2016

Article Number: 
This work was performed under CMS Contract Number HHSM-500-2005-00027I.
Related Data File Families: 
Related Data File Variables: 


The process and materials mentioned as part of this KnowledgeBase article are current, as of the publication date on the article, to the best of our knowledge. The examples provided are correct in the aggregate but may not apply to every subgroup or circumstance that a researcher may wish to study. It is up to the researcher to conduct analysis and confirm that the patterns described in this KnowledgeBase article apply to his/her particular study. If your research findings appear to contradict the advice provided, please contact ResDAC at