Pharmacologic Response to a Diagnosis of Late-Life Depression: A Population Study in Quebec

Abstract

To identify predictors of receiving psychoactive medication and receiving recommended first-line pharmacotherapy in individuals with newly diagnosed late-life depression. We undertook a retrospective database cohort study of 5258 beneficiaries of the Quebec provincial health insurance plan between 1999 and 2002. Subjects were aged 65 to 84 years and diagnosed with depression by primary care physicians or psychiatrists between October 2000 and March 2001; they had no depression diagnosis in the previous year. We defined receipt of psychoactive medication as having a pharmacy claim in the year following the depression diagnosis. We determined receipt of recommended first-line pharmacotherapy from the first psychoactive medication dispensed following diagnosis and defined it accordingly; we defined first-line pharmacotherapy according to the 2001 Canadian Psychiatric Association guidelines. We used multivariate generalized estimating equations models to identify the determinants of the 2 outcomes. A total of 4421 (84.1%) patients received psychoactive medication following diagnosis; 2623 (59.3%) patients had not received antidepressants in the previous year. Of these, 1310 (49.9%) received recommended first-line pharmacotherapy. Independent predictors of receiving psychoactive medication were female sex, depression not otherwise specified (NOS), increasing comorbidity, and living in rural areas. Independent predictors of receiving recommended first-line pharmacotherapy were male sex, depression NOS, receiving medication in the month following diagnosis, and having the same physician diagnosing and treating the patient. Male sex and continuity of care predicted that patients had the recommended medication dispensed.