JNC VI guidelines

Abstract

Curt Furberg and Bruce Psaty1Furberg CD Psaty BM JNC VI: timing is everything.Lancet. 1997; 350: 1413-1414Summary Full Text Full Text PDF PubMed Scopus (15) Google Scholar express the belief that the just-released JNC2Staessen JA Fagard R Thijs L et al.Randomised double-blind comparison of placebo and active treatment for older patients with isolated systolic hypertension (Syst-Eur Trial).Lancet. 1997; 350: 754-764Summary Full Text Full Text PDF PubMed Scopus (22) Google Scholar report is closer to a consensus-based than an evidence-based practice guideline, and will disappoint clinicians who prefer evidence-based guidelines. As a co-author of the JNC VI, and a practicing family physician who adheres to an evidence-based approach to health care, I must disagree. Furberg and Psaty describe an evidence-based guideline as one that makes no recommendation at all on issues for which clinical trial evidence of benefit is absent: this is the narrowest view of evidence-based medicine and of evidence-based, practice-guideline formulation. Evidence-based health care does not mean disregarding all evidence below the level of prospective RCTs. It does mean that evidence from observational studies of outcomes and from studies of physiological endpoints is regarded with circumspection, and good RCT evidence about real clinical outcomes drives practice where such evidence is available. However, grade-B evidence is still evidence and appropriately applied in the absence of better. Similarly, recommendations based on grade-B evidence is not an exclusion criterion for an evidence-based clinical policy. Rather, an evidence-based policy will make explicit the level of evidence on which its recommendations are based, and may make recommendations of varying strength (eg, standards, guidelines, and options) in relation to the strength of evidence.3SHEP Cooperative Research GroupPrevention of stroke by antihypertensive drug treatment in older persons with isolated systolic hypertension. Final results of the Systolic Hypertension in the Elderly Program (SHEP).JAMA. 1991; 285: 3255-3284Google Scholar, 4Cappuccio FP Markandu ND Camey C et al.Double-blind randomised trial of modest salt restriction in older people.Lancet. 1997; 350: 850-854Summary Full Text Full Text PDF PubMed Scopus (149) Google Scholar The JNC VI does make explicit the levels of evidence supporting its recommendations and does recommend drugs shown to improve outcomes. It is true, as Furberg and Psaty assert, that recommendation for thiazide diuretics and β-blockers is not made until two-thirds of the way into the treatment section, However, no class of drug is mentioned until that point. Furberg and Psaty make much of the qualification that diuretics and β-blockers are recommended “if there are no indications for another type of drug”, but without noting that those indications are spelled out rather restrictively and with clear annotation as to their basis in evidence. For example, ACE inhibitors are considered for diabetic patients, and carvedilol for heart failure patients, on the basis of outcome data on their effects on renal disease and congestive-heart-failure mortality respectively. The JNC VI does fall somewhat short of a full-scale, evidence-based clinical policy. That is unavoidable, owing to the constraints on the process and the great cost involved in constructing a full-scale clinical policy on a topic as broad as hypertension. However, it is much closer to an evidence-based policy than to one based on opinion and consensus; Furberg and Psaty err in asserting the opposite, on the basis of a much too narrow definition of evidence and evidence-based health care.