Incidence and risk of mood disorders in patients with breast cancers in Taiwan: a nationwide population-based study

Objective The objective of this study is to assess the incidence and risk of mood disorders, including major depression, anxiety, and bipolar disorders, in Taiwanese patients after the diagnosis of breast cancer compared with a matched cohort. Methods From January 2000 to December 2005, 26,629 newly diagnosed breast cancer patients were enrolled by the Taiwan National Health Insurance program database. The control cohort was selected randomly from 1,000,000 National Health Insurance beneficiaries from a population of 21,400,826 enrolled throughout Taiwan. Each patient was matched with one subject without breast cancer by age, sex, and presence of comorbidities with the same diagnosis index date. The diagnosis of mood disorders was defined by compatible International Classification of Diseases, 9th revision, clinical modification codes plus the prescription of antidepressants for at least 30 days. Results The overall incidence rate ratio of mood disorders was 1.33 (95% CI 1.28–1.39, p