Monday, March 10, 2014

Weight loss medications: how much of a solution are they?

- Jennifer Middleton, MD, MPH

I have patients requesting prescriptions for a weight loss medication nearly every week, and I suspect that many family docs could report the same. Some of these patients would likely benefit from losing 10-20% (or more) of their body weight, and some just want to lose "that last 5 pounds." Some of these patients are already doing a great job with lifestyle modifications, and some want the ease of a pill that allows them to avoid exercise and/or nutrition changes. I rarely prescribe weight loss medications, as I have doubts about their long-term efficacy, and I worry about their side effects. I will only prescribe them to a patient who is already working on lifestyle changes and would likely benefit from a significant weight loss.

The current issue of AFP includes a POEM of a systematic review published in JAMA earlier this year regarding the benefit of prescription weight loss medications. This thoughtful systematic review only included studies of at least 1 year's duration and looked at lipid, glucose, and blood pressure outcomes in addition to weight lost.

The medications included in the review were orlistat, lorcaserin, and phentermine/topiramate. Interestingly, no studies examining phentermine alone met the systematic review's 12 month duration requirement, even though, as the POEM notes, it's the most commonly prescribed weight loss medication. The AFP POEM provides the average weight lost among all studies (2.5 - 8.0 kg), which is a useful adjunct to the wide range of "successful weight loss" (where "success" = at least 5% body weight lost) percentages quoted in the original study's abstract.

All of the studies measured the effect of these medications along with nutrition and exercise changes, so I feel justified in continuing to insist upon lifestyle changes prior to initiating treatment with any of these medications. The authors also recommend discontinuing weight-loss medications if 5% body weight is not lost in 12 weeks, as participants who did not lose at least that much weight were unlikely to lose any after continued medication.

The POEM points out that this systematic review did not, however, find any evidence of POEM (Patient Oriented Evidence that Matters) level benefit for these medications besides weight loss. Lipid, glucose, and blood pressure readings are all disease-oriented evidence (DOE); we have no studies to date showing that any of these medications reduce complications from hypertension, diabetes, heart disease - or even whether they help people live longer. It seems reasonable to assume that patients who lose weight with these medications will improve their risk of those complications, but that's only an unverified inference at this point.

The study's authors state that "[t]he need for constant vigilance to sustain behavior changes in the face of biologic and environmental pressures to regain weight emphasizes the challenges faced by even the most motivated patients who have achieved weight loss." They then use this statement to validate the importance of weight loss medications as a way to combat those pressures. Frankly, I'd prefer to see us work to lessen those biologic and environmental pressures instead of adding another pill to our patients' regimens. Our commitment as 21st century family physicians must be to our communities as well as our individual patients if we are ever to turn the tide of rising obesity rates. There's an AFP By Topic on obesity if you'd like to read more.

That said, here in the here and now, these medications may have a role to play. Are you prescribing medications to help your patients lose weight? If so, how do you choose which patients to prescribe them to?


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