Alternative Risk-Adjustment Approaches to Assessing the Quality of Home Health Care: Final Report. Source of Data


OASIS, as noted above, is the source of the data used in OBQI. Agencies are required to collect OASIS at different points in time over a patient’s stay. The reason for an assessment is recorded on the OASIS instrument from among the following categories:

01  =  Start of Care (SOC)--further visits planned
02  =   Start of Care (SOC)--no further visits planned (discontinued 12/2002)
03 =  Resumption of Care (ROC) (after inpatient stay)
04 =  Recertification (Follow-Up) assessment (every 60 days)
05 =  Other Follow-Up (when there is a significant change in patient condition)
06 =  Transferred to an Inpatient Provider--patient not discharged from agency
07 =  Transferred to an Inpatient Provider--patient discharged from agency
08 =  Death at Home
09 =  Discharged from Agency to the Community
10 =  Discharged from Agency--no visits completed after SOC/ROC assessment (discontinued 12/2002)

There is some variation in the data items collected depending on the reason for the assessment. Baseline data for risk-adjustment and the health status quality indicators are from SOC, ROC and Other Follow-Up assessments. Data from assessment types 06-09 are used to determine changes in health status as well as utilization outcomes. OASIS is described in detail at

The data analyzed in this project were obtained from the CMS contractor at the University of Colorado. They drew the data from the OASIS National Repository at CMS to create discrete episodes of home health care during calendar year 2001. The file includes all episodes of care beginning and ending within the calendar year. Approximately 1,500,000 OASIS episodes are present in the overall data set. The University of Colorado randomly assigned about a third of the episodes to the developmental sample for initial estimation of risk-adjustment models for most outcomes. The remaining 1,000,000 were used to validate the final models derived from analysis of the developmental sample.

The data set contains the OBQI outcome indicators and 143 potential risk-adjusters derived from OASIS. The University of Colorado replaced any missing values for the risk-adjusters with mean values from the sample used to develop their risk-adjustment models. A technical memo documenting the creation and coding of risk factors in the current models has been written by staff at the University of Colorado and can be downloaded from All of the data needed to replicate the risk-adjustment models employed in OBQI and HHQI at the time of the study were included on the files.

The project estimated preliminary models using the 143 candidate risk-adjusters developed by the University of Colorado. Following the TAG meeting (see below), a small number of potentially important risk-adjusters available on raw data files edited by the CMS contractor were requested by the project team and provided by the University of Colorado.

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