Antipsychotic drug exposure and risk of pneumonia: a systematic review and meta-analysis of observational studies

Purpose: Pneumonia is one of the major leading causes of morbidity and mortality among persons aged 65 years or older. Recently, several studies suggested an association between antipsychotic (AP) use and risk of pneumonia in elderly patients. The aim of the present systematic review and meta-analysis of observational studies was to investigate if first-generation and second-generation AP drugs increase the risk of pneumonia in the elderly and also in the younger population, and to ascertain the risk associated with exposure to individual drugs.

Methods: All observational cohort or case-control studies that reported data on pneumonia outcomes in individuals exposed to AP drugs as compared with individuals unexposed or with past exposure to AP drugs were included in the systematic review and meta-analysis. Study participants were of either sex and of any age with no restrictions in terms of diagnostic categories.

Results: The risk of pneumonia was significantly increased by exposure to first-generation AP drugs (odds ratio (OR) 1.68, 95% confidence interval (95%CI) 1.39-2.04, I(2) = 47%) and exposure to second-generation AP drugs (OR 1.98, 95%CI 1.67-2.35, I(2) = 36.7%). The risk was similar among different diagnostic categories and age groups, in elderly and young-adult populations; the finding on age was corroborated by a meta-regression analysis, which did not detect any relationship between age and risk of pneumonia. Only few studies provided data on individual drugs.

Conclusion: Systematic review of current observational evidence suggests that exposure to first-generation and second-generation AP drugs is associated with an increased risk of pneumonia. The present systematic review expands previous knowledge by showing that the increased risk not only applies to elderly individuals but also to younger patients. The information about the risk of pneumonia for individual compounds is still very limited.