What are the benefits of treating mild hypertension?
Treating mild hypertension over five years decreases the risk of stroke, cardiovascular (CV) death, and overall mortality in a small proportion of patients. The numbers needed to treat (NNT)—the numbers of patients who need to be treated to prevent one additional outcome from occurring—are below. Pay attention to the confidence intervals (CIs), which tell us the best/worst case possibilities. Also, note that some of these intervals are very large, meaning that we cannot place much confidence in the reported NNT. (Level of Evidence = 1a)
The authors used the literature search results of a previous Cochrane meta-analysis and updated it by searching several databases. They included studies that lasted at least one year and evaluated treatment of grade 1 hypertension (range = 140/90 mm Hg to 159/99 mm Hg) in patients with no previous cardiac disease. They were able to use individual patient data (instead of comparing only the results across studies) for a total of 15,266 patients. The risk of bias in the studies was low. The research included single-drug treatment and stepped-care approaches. Over an average five years of treatment, there was no significant decrease in overall CV events, coronary events, or, predictably, heart failure. The likelihood of a stroke, death due to a CV event, or all-cause mortality was lower with treatment (see below). Overall, 5.6% of patients withdrew from treatment because of adverse effects (number needed to treat to harm = 36; 95% CI, 23 to 75). Other NNTs for the five years (95% CI) included: stroke = 173 (108 to 810); CV death = 95 (55 to 1,188); overall mortality = 99 (66 to 273); heart failure = not significant; and coronary events = not significant.
Study design: Meta-analysis (randomized controlled trials)
Funding source: Government
Setting: Various (meta-analysis)
Reference: SundströmJArimaHJacksonRet alBlood Pressure Lowering Treatment Trialists' CollaborationEffects of blood pressure reduction in mild hypertension: a systematic review and meta-analysis. Ann Intern Med2015; 162( 3): 184– 191.