Adapting the Rx-Risk-V for mortality prediction in outpatient populations

Med Care. 2006 Aug;44(8):793-7. doi: 10.1097/01.mlr.0000218804.41758.ef.


Objectives: We sought to operationalize, test, and validate an outpatient pharmacy-based case-mix adjuster.

Methods: Outpatients from the Department of Veterans Affairs (VA) prescribed a nonsteroidal anti-inflammatory drug (NSAID) or cyclooxygenase-2 selective drug during 2002 were identified. We updated and extended the Rx-Risk-V by adding 26 additional disease categories and mapping them to VA drug-class codes; derived empirical weights for each from a logistic model of 1-year mortality; adjusted for age, race and sex; and scored the weights into 1 measure of comorbidity. We compared the weighted score to the Deyo diagnosis-based comorbidity index and validated it in a national cohort of 260,321 outpatients with chronic heart failure (CHF).

Results: One-year mortality among the 724,270-outpatient NSAID cohort was 1.6% (n = 11,766). Using a baseline model of age, race, and gender (c-index = 0.716), we found that the Deyo measure improved the prediction of mortality (c-index = 0.765), and the pharmacy comorbidity score further improved the prediction (c-index = 0.782), an increase of 25.8%. Using both, we found further improvement (c-index = 0.792). Among the CHF cohort, 9.7% (n = 25,251) died within 1 year. Performance of the baseline model controlling for age, race, and gender (c index = 0.620) improved with addition of the pharmacy comorbidity score (c index = 0.689), compared with the addition of the Deyo measure (c index = 0.651), an increase of 55.1%. Together, they slightly improved prediction in CHF patients (c index = 0.695).

Conclusions: The updated and extended Rx-Risk-V is useful for case-mix adjustment of mortality in an outpatient population.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Validation Study

MeSH terms

  • Aged
  • Anti-Inflammatory Agents, Non-Steroidal / therapeutic use*
  • Cohort Studies
  • Cyclooxygenase 2 Inhibitors / therapeutic use
  • Female
  • Heart Failure / drug therapy
  • Heart Failure / mortality*
  • Humans
  • Male
  • Middle Aged
  • Outpatients*
  • Risk Adjustment / methods*
  • Risk Assessment*
  • Veterans


  • Anti-Inflammatory Agents, Non-Steroidal
  • Cyclooxygenase 2 Inhibitors