Adherence to Antidepressants Is Associated With Lower Mortality: A 4-Year Population-Based Cohort Study

Objective: Despite the growing use of antidepressants and the potential grave consequences of inadequate treatment, little is known about the impact of adherence to antidepressant treatment on mortality in the general population. The objective of this study was to evaluate the association between adherence to antidepressants and all-cause mortality in a population-based cohort.

Methods: Data were extracted from the electronic medical record database of the largest health provider in Israel (53% of the nation’s population) on a total of 251,745 patients aged 40 years and above who filled an antidepressant prescription at least once between 2008 and 2011. The main outcome measure was all-cause mortality during the study period. Adherence was measured as a continuous variable representing possession ratio (duration of filled antidepressant divided by duration of prescribed antidepressant). A polynomial model of proportional hazard Cox regression for multivariable survival analysis was used, adjusting for demographic and clinical variables that affect mortality.

Results: The association between adherence and the hazard ratio (HR) for mortality follows a quadratic model in which the lowest HR (0.66 [95% CI, 0.64-0.69]) is at a level of 60% adherence in respect to nonadherence.

Conclusions: Adherence to antidepressants is significantly associated with a corresponding decrease in the risk of mortality, controlling for relevant covariates. Physicians from all disciplines should actively improve their patients’ adherence to antidepressants since their persistent use is associated with increased survival.