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Rebuttal: Do β-blockers have a role in treating hypertension?

NO

Drs Khan and McAlister conclude that "β-blockers should not be used for first-line monotherapy in elderly patients with hypertension" but that they "remain reasonable first-line treatment for patients younger than 60 with uncomplicated hypertension." Space unfortunately limits a thorough discussion of all the points made in their article, but their conclusions appear to be based primarily on their recently published meta-analysis.¹ What did this show?

In the studies that compared β-blockers with placebo, by the slimmest of margins (relative risk [RR] 0.86; 95% confidence interval [CI] 0.74–0.99), fewer patients younger than 60 who received β-blockers developed an a priori–determined end point (composite cardiovascular outcome of death, non-fatal myocardial infarction, or non-fatal stroke). Interestingly, the RR was very similar for patients older than 60, but this did not reach statistical significance (RR 0.89; 95% CI 0.75–1.05). Most important, the 95% CI for these groups almost completely overlaps, so these data cannot be used to conclude that the 2 age groups respond differently to β-blockers.

Their second group of findings (β-blockers versus other drugs) suggests that patients older than 60 who received β-blockers developed more end points, again just reaching statistical significance (RR 1.06; 95% CI 1.01–1.10). Interestingly, the authors state that they "did not have access to individual patient data," so they used the mean age of trial participants to make decisions about which studies would be included in each group. Two of the studies included in the older than 60 age group (accounting for 38% of the patients) were the NORDIL and ASCOT-BPLA studies. In these studies the mean ages were 60.4 and 63, respectively. So in other words, an important percentage of the subjects allocated to this group were younger than 60 (the actual number cannot be determined because individual data are not available). This issue alone should bring their results into question.

In my opinion, the data for β-blockers are under-whelming compared with data for some other agents, in particular thiazides, which, I believe, are the true first-line agents—yes, even among type 2 diabetics.^2,3 But on the evidence hierarchy, "expert" opinion is the lowest form of evidence—so I encourage readers to look at the data and draw their own conclusions.

References

1. Khan N, McAlister FA. Re-examining the efficacy of β-blockers for the treatment of hypertension: a meta-analysis. CMAJ 2006;174:1737-42.[Abstract/Free Full Text]
2. Casas JP, Chua W, Loukogeorgakis S, Vallance P, Smeeth L, Hingorani AD, et al. Effect of inhibitors of the renin-angiotensin system and other antihy-pertensive drugs on renal outcomes: systematic review and meta-analysis. Lancet 2005;366:2026-33.[Medline]
3. Whelton PK, Barzilay J, Cushman WC, Davis BR, Iiamathi E, Kostis JB, et al. ALLHAT Collaborative Research Group. Clinical outcomes in antihypertensive treatment of type 2 diabetes, impaired fasting glucose concentration, and normoglycemia: Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). Arch Intern Med 2005;165:1401-9.[Abstract/Free Full Text]

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