Wednesday, March 28, 2018

For hypertension and diabetes, lower treatment targets are not necessarily better

In a previous Medscape commentary, I criticized the 2017 American College of Cardiology / American Heart Association clinical practice guideline on high blood pressure in adults, which proposed lowering the threshold for hypertension from 140/90 to 130/80 mm Hg. Independently, the American Academy of Family Physicians and the American College of Physicians both declined to endorse this guideline, citing concerns about its methodology (e.g., no quality assessment for included studies), management of intellectual conflicts of interest, and lack of information on harms of intensive drug therapy.

The March 15th issue of American Family Physician included a Practice Guideline summary and an editorial perspective on the ACC/AHA guideline by Dr. Michael LeFevre, a member of the panel that developed the JNC 8 guideline for hypertension in adults. In his editorial, Dr. LeFevre pointed out that the guideline's strengths include its emphasis on proper blood pressure measurement technique to avoid overtreating adults with normal out-of-office blood pressures. On the other hand, he argued that "it is an overreach" to classify everyone with a blood pressure above 130/80 as having uncontrolled hypertension. He predicted that since intensive behavioral counseling has only modest benefits in lowering blood pressure, many patients at low risk of cardiovascular disease will end up being treated with medication:

Much harm will come if this change [to the definition of hypertension] is widely accepted and implemented, particularly if quality measures that echo this definition are put into place. Harms from the consequences of poor measurement, overmedication, and arbitrary quality measures can easily offset the small reduction in CVD events found in trials of high-risk persons.

Blood pressure is not the only area of family medicine where there is ongoing debate about appropriate treatment thresholds. In a recent clinical guidance statement, the American College of Physicians recommended that clinicians "aim to achieve an HbA1c level between 7% and 8% in most patients with type 2 diabetes," and "consider deintensifying pharmacologic therapy in patients with type 2 diabetes who achieve HbA1c levels less than 6.5%." This statement elicited a critical response from the American Diabetes Association and endocrinology groups, who argued that lower blood glucose targets are sometimes appropriate to reduce the risk of microvascular and perhaps cardiovacular complications.

This debate between lower and higher A1c targets has been ongoing for years, as illustrated by a pair of Pro and Con editorials on this topic that appeared in AFP in 2012. On the whole, however, more relaxed glucose control can have substantial benefits, especially for older persons with type 2 diabetes, as Dr. Allen Shaughnessy and colleagues argued in 2015:

A large part of the acceptance that “lower is better” hinges on a false belief that a pathophysiologic approach to decision making is always correct. It seems logical that reducing blood glucose levels to nondiabetic normal, no matter the risk or cost, should result in improved patient outcomes. But it doesn't. Today, an older patient with type 2 diabetes is more likely to be hospitalized for severe hypoglycemia than for hyperglycemia.

Underlining this point, a vignette-based study in the March/April issue of Journal of the American Board of Family Medicine found that primary care clinicians (particularly internists and nurse practitioners) would often chose to intensify glycemic control in an older adult with a HbA1c level of 7.5% and multiple life-limiting comorbidities. As family physicians look for opportunities to improve care for patients with hypertension and diabetes, we should not miss opportunities to avoid harm.

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A slightly different version of this post first appeared on the AFP Community Blog.

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