Angiotensin-converting enzyme inhibitor use and protection against pneumonia in patients with diabetes

Because of the high risk of pneumonia in patients with diabetes, we aimed to assess the effect of angiotensin-converting enzyme (ACE) inhibitor use on the occurrence of pneumonia in a general population of patients with diabetes. The study population comprised all patients in the UK General Practice Research Database who had a diagnosis of diabetes (both type 1 and type 2) between 1987 and 2001. Cases were defined as patients with a first diagnosis of pneumonia. For each case, up to four controls were matched by age, gender, practice, and index date. Patients were classified as current ACE inhibitor user when the index date was between the start and end date of ACE inhibitor therapy. Conditional logistic regression analysis was used to estimate the strength of the association between ACE inhibitor use and pneumonia risk. ACE inhibitors were used in 12.7% of 4719 cases and in 13.7% of 15,322 matched controls [crude odds ratio (OR)=0.92, 95% confidence interval (CI)=0.82-1.01]. After adjusting for confounding, ACE inhibitor therapy was associated with a significant reduction in pneumonia risk (adjusted OR=0.72, 95% CI=0.64-0.80). The protective association was consistent across different relevant subgroups with the strongest association in patients with a history of stroke. There was a significant dose-effect relationship (P for trend < 0.001). The use of ACE inhibitors is associated with a significant reduction in pneumonia risk and, apart from blood pressure-lowering properties, may be useful in the prevention of pneumonia in patients with diabetes.