Exposure to potentially harmful drug-disease interactions in older community-dwelling veterans based on the Healthcare Effectiveness Data and Information Set quality measure: who is at risk?

OBJECTIVES: To identify prevalence and risk factors for exposure to drug-disease interactions included in the Healthcare Effectiveness Data and Information Set (HEDIS) Drug-Disease Interaction (Rx-DIS) measure.
DESIGN: Cross-sectional retrospective database analysis.
SETTING: Outpatient clinics within the Department of Veterans Affairs (VA). PARTICIPANTS: Individuals aged 65 and older who received VA outpatient care between October 1, 2003, and September 30, 2006. MEASUREMENTS: Rx-DIS exposure based on the HEDIS measure was identified in VA patients with dementia, falls, and chronic renal failure using VA pharmacy and administrative databases. Factors associated with Rx-DIS exposure were examined, including demographic, health status, and access-to-care factors, including VA outpatient health services use and copayment status.
RESULTS: Of the 305,041 older veterans who met criteria for inclusion, the 1-year prevalence of Rx-DIS exposure was 15.2%; prevalence was 20.2% for dementia, 16.2% for falls, and 8.5% for chronic renal failure. Patients with high disease burden (physical, psychiatric, number of medications) were significantly more likely to have Rx-DIS exposure, regardless of condition. Hispanics and individuals with no copayments were more likely to have Rx-DIS exposure than whites or those with required copayments. There was variation in other predictors based on the type of Rx-DIS.
CONCLUSION: The prevalence of Rx-DIS was common in older VA outpatients. Future studies should examine the risk of Rx-DIS exposure on health outcomes using separate analyses for each type of Rx-DIS separately before combining all Rx-DIS into a single measure of exposure. Studies that examine the effectiveness of interventions to reduce Rx-DIS exposure will also be helpful in improving the quality of care for older adults.