Predictors of medication adherence and associated health care costs in an older population with overactive bladder syndrome: A longitudinal cohort study

Purpose: We examined the relationship between self-reported health status data, subsequent antimuscarinic medication adherence and health care service use in older adults with OAB syndrome in a managed care setting. Materials and Methods: This was a longitudinal cohort study of older adults in the southeastern United States with OAB who completed a health status assessment, used antimuscarinic medications and were enrolled in an HMO continuously for 1 to 3 years. Demographic, clinical and use related economic variables were also retrieved from the administrative claims data of patient HMOs. Prescription refill patterns were used to measure medication adherence. Associations were examined with a sequential, mixed model regression approach. Results: A total of 275 patients were included. The severity of comorbidity (Charlson index), patient perception of quality of life (Short Form-12 scores) and total number of prescribed medications during the year prior to enrollment in a Medicare HMO were independently associated with decreased antimuscarinic MPRs after enrollment. After controlling for other variables increased antimuscarinic MPR remained the strongest predictor of decreased total annual health care costs (5.6% decrease in annual costs with every 10% increase in MPR, p <0.001). Conclusions: We found strong associations between decreased antimuscarinic medication adherence and increased health care service use in older adults with OAB in a managed care setting. Health status assessments completed at enrollment had the potential to identify enrollees at higher risk for nonadherent behaviors and poor health related outcomes.