Decreased persistence to cholinesterase inhibitor therapy with concomitant use of drugs that can impair cognition
Study Objectives. To assess persistence with cholinesterase inhibitor therapy 6 months after the start of treatment, and to determine whether the likelihood of persistence is associated with the coprescription of drugs that can impair cognition. Design. Retrospective cohort study. Setting. Community (home residence) or long-term care facility. Patients. A total of 1183 patients enrolled in the Rhode Island Medicaid program, aged 45 years or older, who were dispensed a cholinesterase inhibitor from January 1, 2000-June 30, 2002. Measurements and Main Results. Patients were considered persistent with treatment if they filled at least five prescriptions for a 1-month supply of the same cholinesterase inhibitor, without an extended gap in days between refills. We compared rates of persistence among patients receiving and those not receiving drugs that can impair cognition. Covariates assessed were patient age, sex, race, and care setting. Approximately one in four patients discontinued cholinesterase inhibitor therapy within 6 months. Patients aged 85 years or older were more persistent than younger patients (77% vs 71%, p<0.05). Caucasian patients were more likely to be persistent than non-Caucasian patients (74% vs 52%, p<0.001). Patients living in the community were less likely to persist than those residing in long-term care facilities (58% vs 76%, p<0.001). After adjusting for race and care setting, patients who were prescribed drugs that can impair cognition were more likely not to have persisted with cholinesterase inhibitor therapy at 6 months than those who did not receive such drugs (odds ratio 1.56, 95% confidence interval 1.13-2.16). Conclusion. A substantial percentage of patients who began receiving cholinesterase inhibitor therapy had discontinued the therapy within 6 months. Many patients also received prescriptions for agents that can impair cognition. Our findings indicated a modest but statistically significant increase in likelihood of treatment discontinuation among patients who also received prescriptions for drugs that can impair cognition. Iatrogenic causes of dementia are important to recognize and address so that therapies for enhancing cognition can be fully effective.