US journal finds lower risk from diet pills

BMJ 1997; 315 doi: (Published 22 November 1997) Cite this as: BMJ 1997;315:1327
  1. Deborah Josefson
  1. San Francisco

    An independent survey conducted by the Wall Street Journal (31 October) has found a lower prevalence of cardiac valve abnormalities in people who took the drugs phentermine and fenfluramine (“phen-fen”) than previously reported.

    These prescription diet pills were approved for short term treatment of obesity over 20 years ago. Twenty million Americans are obese, and excess weight is an independent risk factor for various illnesses such as hypertension, heart disease, kidney disease, and cancer.

    Recently they have been prescribed for prolonged periods in patients who were only mildly overweight. Eighteen million prescriptions were written for the drugs in 1996. The Food and Drug Administration (FDA) took the combination off the market in September after five medical centres reported an alarming rate of valvar dysfunction in patients taking the pills.

    In July doctors from the Mayo Clinic reported 24 cases of valvar heart disease in women taking the drugs. Some of the cases were uncovered when patients presented for valve replacement surgery. The FDA asked for additional data. Five medical centres responded, and a cumulative rate of 32% of valve anomalies were detected in tests on 291 patients.

    Commenting on the action, Dr Michael Friedman, deputy commissioner of the FDA, said: “The data we have obtained indicate that fenfluramine and the closely related dexfenfluramine present an unacceptable risk at this time to patients who take them.”

    In the Wall Street Journal's survey, data were collected on 746 patients who had taken the pills in 21 medical centres. Valvar leaks were found in only 57 (8%) of these patients, a lower figure than that cited by the FDA.

    The Wall Street Journal interviewed cardiologists who had performed echocardiography, after the recall of the drugs, in patients who had taken the diet drug. Dr Daniel Kulick, of Mission Internal Medical Group in California, said that he had performed echocardiography in about 50 patients who had taken the drugs but found only one “possible” case.

    Both the FDA's and the Wall Street Journal's studies were informal and not rigidly controlled scientific experiments. Differences in duration of drug treatment and in dosage were not taken into account. Both surveys relied on echocardiographic interpretations of heart valves, a subjective technique. Another possibility is that the valve dysfunction remitted when the drugs were withdrawn, in which case later surveys would reflect a lower incidence of the disease.

    The US Department of Health and Human Services has now issued preliminary guidelines on the drugs. They suggest users should be given a physical examination regardless of how long they are taking the drugs. Patients who develop signs of heart failure, such as shortness of breath or chest pains, should be given echocardiography.

    Information released at the recent North American Association of Obesity conference which cited a rate of 25% of valve abnomalities in obese patients who took the drugs compared with 1% in the control group upholds the decision to withdraw the drugs.

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