Risk of Hospitalization for Community Acquired Pneumonia with Renin-Angiotensin Blockade in Elderly Patients: A Population-Based Study

Objective: To characterize the 90-day risk of hospitalization with pneumonia among patients treated with different anti-hypertensive drug classes. Design: Population based cohort study using five linked databases. Participants: Individuals over the age of 65 who filled a new outpatient prescription for one of four anti-hypertensive medications: ACE inhibitors (n = 86 775), ARBs (n = 33 953), calcium channel blockers (CCB, n = 34 240), beta blockers (BB, n = 35 331) and thiazide diuretics (n = 64 186). Primary Outcome: Hospitalization with pneumonia within 90 days of a qualifying prescription. We adjusted for ten a priori selected covariates, including age, sex, diabetes and number of visits to a family doctor. Results: Baseline characteristics of the groups were relatively well matched, except for age, sex, diabetes and frequency of family doctor visits. 128 of the 86 775 patients (0.15%) initiated on an ACE inhibitor and 43 of the 33953 patients (0.13%) of patients initiated on an ARB were hospitalized with pneumonia in the subsequent 90 days. 135 of 64 186 patients (0.21%) initiated on a thiazide, 112 of 35 331 patients (.32%) initiated on a BB, and 89 of 34 240 (0.26%) patients initiated on a CCB achieved the primary outcome. Compared to calcium channel blockers, ACE inhibitors (adjusted OR 0.61, 95% CI 0.46 to 0.81) and ARBs (adjusted OR 0.52, 95% CI 0.36 to 0.76) were associated with a lower risk of pneumonia. No benefit was seen with thiazides (adjusted OR 0.87, 95% CI 0.66 to 1.14) or beta blockers (adjusted OR 1.21, 95% CI 0.91 to 1.60). Conclusion: Initiating medications that block the renin angiotensin system, compared to other anti-hypertensive medications, is associated with a small absolute reduction in the 90 day risk of hospitalization with pneumonia.