Beta-blockers vs. thiazides in the treatment of hypertension: a review of the experience of the large national trials.
The effects of antihypertensive treatment on cerebrovascular disease and coronary artery disease (CAD) end points reported in the large-scale national trials have differed. All trials have shown stroke benefit, whereas CAD benefit has not been convincingly demonstrated in any. In three trials, the effects of thiazide- and beta-blocker-based regimens can be directly compared. In the MRC Treatment Trial for Mild Hypertension in Britain, the largest of the trials and the only one to compare these two classes of drugs with each other and with untreated controls, stroke benefit was significantly greater in the thiazide than in the beta-blocker group (p = 0.002). Indeed, the 70% reduction in fatal strokes and 65% reduction in nonfatal strokes suggested an effect on cerebral infarction as well as on cerebral hemorrhage. Opposing trends were found for CAD end points with beta-blockers and thiazides when compared with controls. For coronary events, sudden deaths, and ECG changes of infarction, significant differences were found between the reduced rates for those receiving propranolol and the higher rates for those receiving bendrofluazide. Weak evidence has been put forward by four trials-MRFIT, HDFP, the Oslo trial, and the MRC trial-suggesting that thiazide treatment for those who already have evidence of coronary disease may be harmful. In no case is the evidence conclusive, and it involves only a small (but important) subgroup. In the MRC trial, a nonselective beta-blocker, propranolol, provided greater CAD benefit as measured by the incidence of myocardial infarction, sudden death, and ECG changes, but only in nonsmokers. Hypotheses generated by these trials need further investigation.
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Medical Research Council Trial in Britain.
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology / Q000627:therapeutic use*; D001539:Bendroflumethiazide / Q000494:pharmacology / Q000627:therapeutic use; D002986:Clinical Trials as Topic; D003327:Coronary Disease / Q000188:drug therapy; D004232:Diuretics; D004562:Electrocardiography / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D011433:Propranolol / Q000494:pharmacology / Q000627:therapeutic use; D011446:Prospective Studies; D012907:Smoking / Q000009:adverse effects / Q000378:metabolism; D049993:Sodium Chloride Symporter Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D020521:Stroke / Q000517:prevention & control; D006113:United Kingdom
D000319:Adrenergic beta-Antagonists; D004232:Diuretics; D049993:Sodium Chloride Symporter Inhibitors; D001539:Bendroflumethiazide; D011433:Propranolol