Objective: To determine the effect of treatment gaps on the risk of institutionalization or death among community-dwelling elderly patients treated with cholinesterase inhibitors (ChIs).
Methods: A survival analysis was conducted among a cohort of community-dwelling elderly patients (age 66+) newly treated with ChIs identified in the Quebec drug claims databases (Régie de l'Assurance Maladie du Québec [RAMQ]) between January 1, 2000, and December 31, 2007. Treatment nonpersistence during the year following ChI initiation was defined as treatment discontinuation or gaps of at least 6 weeks. To account for reverse causality, Cox proportional hazard modeling was conducted only among patients who did not discontinue treatment, in order to assess the association between treatment nonpersistence and institutionalization or death.
Results: Among the 24,394 elderly ChI users, 4,108 (16.8) experienced a treatment gap during the year following ChI treatment initiation while 596 (2.4%) discontinued their treatment within the first 3 months (early stoppers) and 4,038 (16.6%) after 3 months of treatment (late stoppers). Of all treated patients, 4,409 (18.1%) were institutionalized or died during follow-up. In patients who did not stop their treatment, the risk of institutionalization or death appeared lower in patients who experienced a treatment gap (hazard ratio 0.91; 95% confidence interval 0.86-0.96).
Conclusions: Our results suggest that, contrary to what was previously reported in clinical trials, treatment gaps do not compromise the outcome of patients treated with ChIs in a real-life setting.