The Use of a Clinical Practice Guideline to Manage and Verify the Weight Loss Outcomes of Patients Treated With Fen-Phen in Primary Care Settings

Abstract

Fenfluramine and phenteramine (“fen-phen”) enjoyed immense popularity as a weight loss drug combination until September 15¹, 1997, when fenfluramine was withdrawn from the market because of evidence that it might cause valvular heart disease. In response to the emergence in 1996 of physician disagreement about the appropriate use of diet pills in weight loss treatment plans, MeritCare Health System developed a practice guideline to assist clinicians in the appropriate use of anoretic drugs. The purpose of this report was to answer two questions about MeritCare's experience with fen-phen. First, how was MeritCare able to use a practice guideline to mediate conflict among physicians and to rapidly implement practice changes as imformation about the deleterious effects of fen-phen because available? Second, how effective was fenphen as a weight loss agent when prescribed by doctors who practiced in primary care settings? A retrospective review of the charts of 401 patients treated with fen-phen by primary care physicians practicing in four of MeritCare's Fargo clinics was conducted and MeritCare's experience with fenphen was reviewed. The data show that patients treated with fen-phen experienced, on average, a rapid decline in body mass index (BMI) over the first 4 months of treatment, after which the rate of decline slowed and then reached a plateau. There appeared to be little, if any, further mean weight loss after 6 months. Patients did not, as a rule, achieve target BMIs (defined as 26 to 27) even when treatment was continued for up to 19 months. In fact, after 6 months of treatment with fen-phen, expected decreases in BMI began to be supplanted by increases in BMI, even thought patients remained on fen-phen. The data also reveal wide variations in the weight loss responses of patients treated with fen-phen. Practice guidelines are useful tools in mediating physician disagreement about “best practice” and in rapidly deploying practice changes as new information about “best practice” becomes available. Beneficial weight loss responses to fen-phen prescribed by primary care physicians in standard primary care settings were highly variable and fell short of target weights.