Use clinical judgment when guidelines differ

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The recent publication of differing guidelines for reducing the risk of cardiovascular disease have implications for stroke prevention as well. The authors of an editorial published online Feb. 20 in Stroke described the updates as a step forward but not without controversy.

The American Heart Association (AHA) and the American College of Cardiology (ACC) unveiled a series of prevention guidelines in November 2013 that prompted a wave of criticism over a new calculator to predict atherosclerotic cardiovascular disease risk and the elimination of low-density lipoprotein targets. Critics argued the calculator overestimated risk and would expose more patients to statin therapy. The risk prediction model also included stroke, which was a first.

The Eighth Joint National Committee (JNC), American Society of Hypertension and the International Society of Hypertension released another set of guidelines a month later. The recommendation to change the systolic blood pressure goal from 140 mm Hg to 150 mm Hg also raised concerns, this time for potential undertreatment.

Philip G. Gorelick, MD, of Michigan State University College of Human Medicine in East Lansing, and colleagues listed their concerns with the new recommendations. They wrote that it was not clear what the consequences of expanding the use of statins as a primary prevention under the AHA/ACC guidelines would be. “This is a particularly important issue because even the presence of high risk in select patient populations (e.g., those with isolated heart failure, dialysis for renal insufficiency) does not necessarily equate to benefit from statin therapy.”

The AHA, ACC and Centers for Disease Control and Prevention define hypertension as systolic blood pressure level of 140 mm Hg or more and a diastolic blood pressure of 90 mm Hg or more. The JNC’s recommended threshold might result in an increase in stroke, they wrote, and the discord between the AHA/ACC and JNC targets might confuse providers, payers and the public.

Gorelick and colleagues pointed out the new guidelines address statin therapy and blood pressure targets in the context of heart disease prevention but not stroke prevention or by stroke type. Research supports the use of statins to reduce stroke risk in high-risk populations and they identified other analyses that indicated treatment benefits for other populations as well.

They credited improvement in blood pressure control in the U.S. with a reduction in stroke and considered the 140 mm Hg target reasonable, while even lower targets may be safe in patients with lacunar infarction.

“Guidelines remain important sources of knowledge; however, they have inherent limitations and are not a substitute for clinical judgment and pragmatic reasoning,” they advised.