Late-life depression and the association with multimorbidity and polypharmacy: a cross-sectional study.

Background: Late-life depression often coincides with chronic somatic diseases and, consequently, with polypharmacy, which may complicate medical treatment.

Objective: To determine the associations between patients diagnosed with late-life depression in primary care and multimorbidity and polypharmacy.

Methods: This cross-sectional observational study was performed using 2012 primary care data. Depressed patients aged ≥60 years were compared to age and gender matched patients diagnosed with other psychological diagnoses and mentally healthy controls. Morbidity and prescription data were combined, and regression analyses were performed for the associations between depression and chronic disease and chronic drug use.

Results: We included 4477 patients; 1512 had a record of depression, 1457 of other mental health or psychological diagnoses and 1508 were controls. Depressed patients had a 16% [Prevalence Ratio (PR) 1.16; 95% confidence interval (95% CI) 10%-24%] higher rate of chronic somatic disease and higher odds for multimorbidity (OR 1.55; 95% CI 1.33-1.81) compared with controls. No differences existed between depressed patients and patients with other psychological diagnoses. Compared with controls, depressed patients had a 46% (95% CI 39-53%) higher rate of chronic drug use and higher odds for polypharmacy (OR 2.89; 95% CI 2.41-3.47). Depressed patients also had higher rates of chronic drug use and higher odds for polypharmacy compared with patients with other psychological diagnoses (PR 1.26; OR 1.75; both P < 0.001).

Conclusions: Late-life depression in primary care patients is associated with more chronic drug use, even beyond the increased rates of comorbid somatic diseases. General practitioners should consider medication reviews to prevent unnecessary drug-related problems in these patients.