Predictors of weight loss during treatment with d-fenfluramine

To identify parameters predictive of weight loss during treatment with d-fenfluramine. This may provide a tool to recognize patients who are sensitive to the weight-reducing effect of d-fenfluramine and thus prevent unnecessary prescription.

An open intervention study during which biweekly control visits were scheduled. The study lasted 12 weeks.

The General Internal Medicine outpatient clinic of the Leiden University Hospital. Patients were recruited through a newspaper advertisement.

Forty-eight healthy, obese patients (36 women and 12 men), aged 39 +/- 10 years (mean +/- SD) with a body mass index of 34.3 +/- 4.1 kg/m2 enrolled.

d-Fenfluramine 15 mg twice daily for 12 weeks.

Body weight, height, waist and hip circumference, food intake, smoking habits, obesity history, treatment history, family history of obesity and compliance with the medication scheme were recorded as potential predictors of weight loss.

One patient was withdrawn because of depressive symptoms. Thirteen patients did not lose weight. On average, the other 34 patients lost 5.7 +/- 2.9 kg or 18.1 +/- 9.4% of excess body weight. High compliance with the drug regimen was associated with a twofold greater weight loss (17.7 +/- 12.3 vs. 9.0 +/- 9.4% of excess weight, ANOVA, P = 0.0088). Patients with a positive family history of obesity lost twice as much weight as patients without obese relatives (15.8 +/- 11.8 vs. 6.0 +/- 7.3% of excess weight; ANOVA, P = 0.0078). No other potential determinants were predictive for weight loss.

Informing patients that compliance with the medication scheme improves treatment outcome will be useful. Previous failures to lose weight should not exclude patients from treatment. A positive family history of obesity needs further evaluation as a possible determinant of weight loss in forthcoming studies.