Trends in the Prescribing of Antidepressants Following Acute Myocardial Infarction, 1993–2002

Abstract

There has been a substantial increase in the prescribing of antidepressants on a population basis and in particular serotonin reuptake inhibitors (SSRIs). SSRIs have lower cardiac toxicity than tricyclic antidepressants (TCAs). We examined how the prescribing of antidepressants to patients post-myocardial infarction (MI) changed in the decade 1993 to 2002, including the proportion accounted for by TCAs. A population-based study cross-sectional time series analysis was conducted in which quarterly antidepressant prescription data were obtained for 1993 to 2002 for elderly Ontarians who had experienced an MI, as well as for age- and sex-matched controls with no history of MI. The number of patients varied per quarter, for a total of 68,870 post-MI patients and an equal number of matched controls. Covariates included age, gender, income, and number of medications dispensed in the past year. Post-MI patients were more likely to receive an antidepressant relative to controls, with an overall odds ratio (OR) of 1.34; 95% confidence interval (CI), 1.29-1.38. However, with adjustment for the number of medications received, post-MI patients were 20% less likely to receive an antidepressant relative to controls, adjusted OR = 0.81; 95% CI, 0.78-0.84. The proportion of antidepressants prescribed to post-MI patients accounted for by TCAs decreased, but the proportion of post-MI patients receiving a TCA remained stable at approximately 6%. Increases in the prescription of antidepressants, and in particular SSRIs, to post-MI patients reflect general population trends rather than any special importance attached to treating post-MI depression. The apparent greater likelihood that post-MI patients will receive an antidepressant is reversed when total number of medications is controlled, a proxy for medical utilization and comorbidity.