Richard Lehman’s journal review – 7 March 2011
7 Mar, 11 | by BMJ Group
JAMA 2 Mar 2011 Vol 305
913 A friend recently began a piece on outcomes research with Bishop Joseph Butler’s maxim, “Every thing is what it is, and not some other thing.” If a trial like SOLVD is designed to measure the effect of a particular ACE inhibitor on survival in people with symptomatic left systolic heart failure, it is not the same thing as a trial designed to measure the effect of a beta-blocker following myocardial infarction. The only thing these trials have in common is that they lower blood pressure in people with established cardiovascular disease. Meta-analysts should remember Butler’s maxim. It is simply not legitimate to combine such dissimilar studies, plus a few from the diabetes literature, and use them to generalise about something called “secondary prevention of cardiovascular disease by antihypertensive treatment in persons without hypertension.” The terms are far too broad, and the analysis also doesn’t adjust for the use of other secondary preventive medication such as aspirin and statins. The effect sizes derived are small but positive – but that means nothing. Nor can I see anything in this misguided lump of disparate studies that can justify an editorial called “antihypertensive therapy for prehypertension”. In the case of the heart failure studies, the patients were more likely to have prehypotension. This is what happens when lumping goes mad: every thing becomes some other thing. more…
