Removing the hype from hypertension
BMJ 2014; 348 doi: https://doi.org/10.1136/bmj.g1937 (Published 06 March 2014) Cite this as: BMJ 2014;348:g1937
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Over and above the recognition that, in hypertension research, choosing the wrong design is to choose the wrong answer(1), we should appreciate that incorrect conclusions can also be generated by incorrect technique of blood pressure (BP) measurement(2). In particular the "silence in the literature regarding the subject of inter-arm variability in blood pressure" has a huge potential to introduce a clinically significant difference in BP that has nothing to do with randomised treatment(2). In cohort studies the interarm difference has the potential to generate incorrect conclusions when patients are categorised as being either normotensive or hypertensive solely on the basis of BP measurement in one arm only, the latter being the case in a prospective cohort study which evaluated temporal evolution of cognitive changes in incident hypertension(3).
When design faults and incorrect methodology become institutionalised, the risk is that even systematic reviews and meta analyses might fall prey to the same bias, as might have been the case in a meta analysis which concluded that "RDN (renal denervation therapy) resulted in a substantial reduction in mean BP at 6 months....irrespective of study design"(4)
References
(1) Shun-Shin MJ., Howard JP., Francis DP. Removing hype from hypertension. BMJ 2014;348:10
(2) Giles TD., Egan P. Inter-arm difference in blood pressure may have serious research and clinical implications. Journal of Clinical Hypertension 2012;14:491-2
(3) Kohler S., Baars MAE., Spauwen P et al. Temporal evolution of cognitive changes in incident hypertension. Prospective cohort study across the adult age span. Hypertension 2014;63:245-251
(4)Davis MI., Filion KB., Zhang D et al. Effectiveness of renal denervation therapy for resistant hypertension. A systematic review and meta analysis. J Am Coll Cardiol 2013;62:231-241
Competing interests: No competing interests
Re: Removing the hype from hypertension
We must thank the BMJ editors for their timely publication of the Editorial by Shun-shin et al ‘Removing the hype from hypertension’.[1] It is tempting to rely on uncontrolled studies such as Simplicity I & II for advocating this innovative and invasive procedure for improving blood pressure control.
While the gold standard of randomized placebo controlled trials for medical interventions has been universally accepted for drug therapy [2][3], this has not been the case for surgical or other invasive procedures [4]. Indeed, a recent Editorial in the Wall Street Journal states: ‘The FDA Wants You for Sham Surgery. There are better ways to test medical devices than by having patients be placebos who get fake operations commenting on the Simplicity saga.[5][6] Economy is invading Medicine, but we must not let this intrusion prevent us from doing good Medicine.
Sham interventions are the equivalent of placebo in drug trials. We need more better quality randomized trials for invasive procedures when feasible, including sham interventions, to full assess the real clinical usefulness of the procedures. Sham interventions may expose a limited number of patients to risk. However, in the absence of properly conducted trials many more patients would be exposed to risky and sometimes useless interventions.
Medicine and Economy are becoming increasingly intertwined. More Medicine and more expensive Medicine is not necessarily better Medicine. Certainly, we must include economic evaluations in our appraisal of new therapeutic options. However, the real clinical benefit can only be obtained by an adequate evaluation of medical interventions. This is also true for surgical and invasive procedures
1 Shun-Shin MJ, Howard JP, Francis DP. Removing the hype from hypertension. BMJ 2014;348:g1937–g1937. doi:10.1136/bmj.g1937
2 Guyatt GH, Sackett DL, Cook DJ. Users’ guides to the medical literature. II. How to use an article about therapy or prevention. A. Are the results of the study valid? Evidence-Based Medicine Working Group. JAMA J Am Med Assoc 1993;270:2598–601.
3 Guyatt GH, Sackett DL, Cook DJ. Users’ guides to the medical literature. II. How to use an article about therapy or prevention. B. What were the results and will they help me in caring for my patients? Evidence-Based Medicine Working Group. JAMA J Am Med Assoc 1994;271:59–63.
4 Farrokhyar F, Karanicolas PJ, Thoma A, et al. Randomized controlled trials of surgical interventions. Ann Surg 2010;251:409–16. doi:10.1097/SLA.0b013e3181cf863d
5 Scott Gottlieb: The FDA Wants You for Sham Surgery. http://online.wsj.com/news/article_email/SB10001424052702304680904579365... (accessed 16 Mar2014).
6 WSJ Attack on Sham Surgery Is About Healthy Profits, Not Patients. Forbes. http://www.forbes.com/sites/larryhusten/2014/02/20/wall-street-journal-o... (accessed 16 Mar2014).
Competing interests: No competing interests