Intolerance to Angiotensin Converting Enzyme Inhibitors in Asthma and the General Population: A UK Population-Based Cohort Study

BACKGROUND: Angiotensin converting enzyme inhibitor (ACEI) intolerance commonly occurs, requiring switching to an angiotensin-II receptor blocker (ARB). Angiotensin converting enzyme inhibitor intolerance may be mediated by bradykinin, potentially affecting airway hyperresponsiveness. OBJECTIVE: To assess the risk for switching to ARBs in asthma. METHODS: We conducted a new-user cohort study of ACEI initiators identified from electronic health records from the UK Clinical Practice Research Datalink. The risk for switching to ARBs in people with asthma or chronic obstructive pulmonary disease and the general population was compared. Adjusted hazard ratios (HRs) were calculated using Cox regression, stratified by British Thoracic Society (BTS) treatment step and ACEI type. RESULTS: Of 642,336 new users of ACEI, 6.4% had active asthma. The hazard of switching to ARB was greater in people with asthma (HR = 1.16; 95% confidence interval [CI], 1.14-1.18; P ≤ .001) and highest in those at BTS step 3 or greater (HR = 1.35, 95% CI, 1.32-1.39; and HR = 1.18, 95% CI, 1.15-1.22, P ≤ .001 for patients aged ≥60 and <60 years, respectively). Hazard was highest with enalapril (HR = 1.25, 95% CI, 1.18-1.34, P ≤ .001; HR = 1.44, 95% CI, 1.32-1.58, P ≤ .001 for BTS step 3 or greater asthma). No increased hazard was observed in chronic obstructive pulmonary disease or those younger than age 60 years at BTS step 1/2. The number needed to treat varied by age, sex, and body mass index (BMI), ranging between 21 and 4, and was lowest in older women with a BMI of 25 or greater. CONCLUSIONS: People with active asthma are more likely to switch to ARBs after commencing ACEI therapy. The number needed to treat varies by age, sex, BMI, and BTS step. Angiotensin-II receptor blocker could potentially be considered first-line in people with asthma and in those with high-risk characteristics.