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EDITORIALS: Alice V Stanton Calcium channel blockers BMJ 1998; 316: 1471-1473 [Full text]

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Calcium channel blockers: Is the jury still out?

James M Wright   (20 May 1998)

Calcium channel blockers: Is the jury still out? 20 May 1998
James M Wright, Associate Professor University of BC, Vancouver, BC, Canada Send response to journal: Re: Calcium channel blockers: Is the jury still out?	To the Editor: The editorial on calcium channel blockers (CCBs) by Dr. Stanton is a carefully considered opinion, but it is unfortunately based on an incomplete review of the available evidence. In my search of the literature I have found 6 published randomized controlled trials (RCTs), in which CCBs are compared to other drugs in the treatment of hypertension, and outcome data are collected and reported. The 3 RCTs Dr. Stanton has not considered are the GLANT(1), CASTEL(2), and VHAS(3) trials. The GLANT trial compared an ACE inhibitor, delapril, with dihydropyridine CCBs; the CASTEL trial compared the combination of chlorthalidone and atenolol with nifedipine in an elderly hypertensive population (I have been kindly provided with 12 year outcome data for the individual drugs by Dr. Casiglia); and the VHAS trial compared chlorthalidone with verapamil. If one combines the total cardiovascular events (stroke, coronary heart disease, and congestive heart failure) for the non-CCB drug as compared to the CCB, all 6 trials show a trend towards a benefit for the non-CCB drug; overall odds ratios is 0.50 (99% CI, 0.35 to 0.72). Can all of these trials be discounted as due to random error? It is of course important to be certain that data from all RCTs is included; I would be most interested in hearing about any RCTs I may have overlooked. Relevant data has been collected in the TOMHS trial(4) and should be included, but when I asked for the information, the authors refused to provide it. At the present time many doctors are prescribing CCBs as first-line drugs for hypertension, presumably with the assumption that the overall benefits for the patient will be better than with a thiazide, beta-blocker or ACE inhibitor. In my opinion, the chances that CCBs, particularly dihydropyridines, will cause modest benefit as compared to other anti-hypertensive classes is vanishingly small; on the other hand the chances that they will cause modest harm is substantial. Physicians should therefore act based on this growing evidence, and begin to change their prescribing habits accordingly. James M. Wright, MD, PhD, FRCP(C) Associate Professor (presently on sabbatical in New Zealand) Departments of Pharmacology & Therapeutics and Medicine 2176 Health Sciences Mall University of British Columbia Vancouver, B.C. V6T 1Z3 1. The GLANT Study Group. A 12-month comparison of ACE inhibitor and Ca antagonist therapy in mild to moderate essential hypertension - The GLANT Study. Hypertens Res 1995;18:235-44. 2. Casiglia E, Spolaore P, Mazza A, et al. Effect of two different therapeutic approaches on total and cardiovascular mortality in a Cardiovascular Study in the Elderly (CASTEL). Jpn Heart J 1994;35(5):589-600. 3.Agabiti Rosei E, Dal Palu C, Leonetti G, et al. Clinical results of the verapamil in hypertension and atherosclerosis study. J Hypertens 1997;15:1337-1344. 4. Neaton JD, Grimm,Jr RH, Prineas RJ, et al. Treatment of mild hypertension study: Final results. J Amer Med Assoc. 1993;270:713-724.