Observed association between antidepressant use and pneumonia risk was confounded by comorbidity measures

Objective: A prior study suggested that antidepressants might increase the risk of hospitalization for pneumonia in the elderly. This study sought to confirm or refute this hypothesis. Study Design and Setting: Case-control study of persons aged 65 and above nested in the UK General Practice Research Database. Results: We identified 12,044 cases of the hospitalization for pneumonia (the primary outcome) and 48,176 controls. The odds ratio (OR) for any antidepressant use, adjusting for age, sex, and calendar year was 1.61 (95% confidence interval 1.46-1.78). After further adjustment for comorbidity measures, the OR was 0.89 (0.79-1.00). We also identified 159 cases of hospitalization for aspiration pneumonia (the secondary outcome) and 636 controls. The OR for any antidepressant use, adjusted for age, sex, and calendar year was 1.45 (0.65-3.24). After further adjustment for comorbidity measures, the OR was 0.63 (0.23-1.71). Conclusion: These findings refute the prior hypothesis that use of antidepressants by elderly patients increases the risk of hospitalization for pneumonia or for aspiration pneumonia. Decisions regarding use of antidepressants in elderly persons should not be affected by concern about pneumonia risk. Data-derived hypotheses should be independently confirmed before being acted upon. (c) 2007 Elsevier Inc. All rights reserved.