Amlodipine and angiotensin-converting enzyme inhibitor combination versus amlodipine monotherapy in hypertension: a meta-analysis of randomized controlled trials

Objective This study aimed to estimate the efficacy and tolerability of the combination of amlodipine and angiotensin-converting enzyme inhibitors as compared with amlodipine monotherapy in the treatment of hypertension. Methods The Cochrane Central Register of Controlled Trials, PubMed, and Embase were searched for relevant articles. A random effect model of meta-analysis was used for the selected randomized controlled trials (RCTs). Results A total of 17 randomized controlled trials involving 3291 patients were identified using predefined criteria. The combination treatment of amlodipine and angiotensin-converting enzyme inhibitors resulted in a greater reduction of both systolic blood pressure (SBP) [weighted mean difference (WMD) 5.72, 95% CI: (confidence interval) 4.10-7.33] and diastolic blood pressure (DBP) (WMD 3.62, 95% CI: 4.85-2.39) than monotherapy. The combination treatment also generated significantly greater reductions for the mean ambulatory SBP and DBP during the full 24 hours (WMD: SBP 4.24, 95% CI: 6.82-1.67; DBP 2.23, 95% CI: 3.73-0.69), but not for the trough (WMD: SBP 4.52, 9.56 to -0.51; DBP 3.7, 7.65 to -0.25). The hypertension therapeutic control (SPB < 140, DBP < 90 mmHg) rate for the combination treatment is higher than that for monotherapy [relative risk (RR): 1.36, 95% CI: 1.07-1.73]. The combination treatment also resulted in a lower overall rate of adverse events (RR: 0.86, 95% CI: 0.75-0.99) and edema (RR: 0.40, 95% CI: 0.29-0.56), but a higher rate of cough (RR: 3.28, 95% CI: 2.03-5.29) as compared with monotherapy. Conclusion This meta-analysis suggests that the combination treatment provides superior BP control, fewer adverse events, and better tolerability in hypertensive patients than monotherapy. Further research should explore the mechanism of the combination therapy and whether it is associated with the reduction of cardiovascular disease morbidity and mortality. Blood Press Monit 15: 195-204 (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.