Medication beliefs mediate between depressive symptoms and medication adherence in cystic fibrosis

Objective: Depression is a known barrier to regimen adherence for chronic conditions. Despite elevated depression rates and complex regimens for people with cystic fibrosis (CF), little is known about associations between depressive symptoms and CF adherence. One possibility is that depressive symptoms distort beliefs about medications, which may influence adherence. Method: Adolescents and adults (N = 128; mean age = 29 ± 11 years, range = 16-63, 93% Caucasian) with CF reported on depressive symptoms and medication beliefs (self-efficacy, motivation, perceived importance, and outcome expectancies related to taking medications). Medication adherence was assessed objectively through pharmacy refill data. Cross-sectional structural equation models evaluated medication beliefs as a mediator between depressive symptoms and medication adherence. Results: Twenty-three percent of participants exceeded clinical cutoffs for depressive symptoms. Participants took less than half of prescribed pulmonary medications (mean adherence rate = 44.4 ± 26.7%). Depressive symptoms were correlated with adherence (r = -.22, p < .05), and medication beliefs (b = -0.13, 95% CI [-0.24, -0.03]) significantly mediated this relation. Higher depressive symptoms were associated with less positive medication beliefs (b = -0.27, p < .01), which were associated with lower medication adherence (b = 0.49, p < .01). Conclusions: Depressive symptoms are related to beliefs about and adherence to CF medications. Monitoring depressive symptoms and medication beliefs in routine CF care may help identify risks for nonadherence and facilitate interventions to reduce depression, adaptive medication beliefs, and ultimately improve adherence and CF management.