OBJECTIVES: Several survey studies found that patients with depression had high risk of being non-adherent to medication therapies for other chronic conditions. A previous research suggested that antidepressants had positive impact on glycemic control for diabetes patients possibly related to improved medication adherence after relief of depressive symptoms. We used real-world claims data to examine the association of depression with adherence to three therapeutic classes (3TC): oral diabetes, hypertension and statin medications.

METHODS: This retrospective cohort study used IBM MarketScan^® database. Adults 18-64 years old, who initiated their therapy in 2015, continued taking the 3TC medications and continuously enrolled in 2016 and 2017, were included. The study group patients started anti-depression medications or had depression diagnosis in 2015, while the control group did not. Patients with new diagnosis of depression after 2015 were excluded. Medication adherence were measured using proportion of days covered (PDC) defined by CMS. The adjusted odds ratio (OR) of being non-adherent (PDC<80%) were calculated for 2016 and 2017 after controlling for age, gender, employee classification and status, and geographic location.

RESULTS: About 1/3 patients filling 3TC medications also filled anti-depression medications. The study group (n=652,005) had significantly greater odds of being non-adherent to their established therapies than the control group (n=1,201,656) in 2016: diabetes OR =1.03 (95% CI 1.01-1.05); hypertension OR=1.32 (95% CI 1.30-1.34); and statin OR=1.32 (95% CI 1.30-1.34). The odds of being non-adherent became more substantial in 2017: diabetes OR=1.07 (95% CI 1.06-1.09); hypertension OR=1.55 (95% CI 1.53-1.57); and statin OR=1.52 (95% CI 1.49-1.54).

CONCLUSIONS: Depression has negative impact on medication adherence to treat three chronic conditions, especially for statin and hypertension. To achieve better health outcomes, healthcare providers including clinics and pharmacies should manage depression in conjunction with other chronic conditions.