Adherence to antidepressant medications is associated with reduced premature mortality in patients with cancer: A nationwide cohort study

Background: Depression and anxiety are common in cancer and antidepressants (AD) are efficacious treatment. The relationship between AD adherence and mortality in cancer is unclear. This study aimed to evaluate the association between adherence to AD and all-cause mortality in a population-based cohort of patients with cancer. Materials and Methods: We conducted a 4-year historical prospective cohort study including 42,075 patients with cancer who purchased AD at least once during the study period. Adherence to AD was modeled as nonadherence (<20%), poor (20-50%), moderate (50-80%), and good (>80%) adherence. We conducted multivariable survival analyses adjusted for demographic and clinical variables that may affect mortality. Results: During 1,051,489 person-years at risk follow-up, the adjusted hazard ratios (HR) for mortality were 0.89 (95% confidence interval [CI]: 0.83-0.95), 0.77 (95% CI: 0.66-0.72), and 0.80 (95% CI: 0.76-0.85) for the poor, moderate, and good adherence groups, respectively, compared to the nonadherent group. Analysis of the entire sample and a subgroup with depression, for cancer subtypes, revealed similar patterns for breast, colon, lung, and prostate cancers, but not for melanoma patients. Multivariate predictors of premature mortality included male gender (HR 1.48 [95% CI: 1.42-1.55]), current/past smoking status (HR 1.1, [95% CI: 1.04-1.15]; P < .0001), low socioeconomic status (HR 1.1, [95% CI: 1.03-1.17]; P < .0001) and more physical comorbidities. Conclusions: The present study is the first to demonstrate that higher adherence to AD is associated with a decrease of all-cause mortality in a large nationwide cohort of cancer patients. Our data add to the pressing need to encourage adherence to AD among cancer patients.