Dose-effect of fenfluramine use on the severity of valvular heart disease among fen-phen patients with valvulopathy

OBJECTIVE: To determine whether the severity of valvulopathy was associated with the dosage of fenfluramine taken by fenfluramine-phentermine users with valvulopathy, DESIGN: Out of 105 suspected valvulopathy case reports received by the US Food and Drug Administration (FDA) among fenfluramine-phentermine users, 74 patients meeting FDA case definition for valvulopathy were included in this study. Patients with severe valvulopathy were classified as those either undergoing valve replacement surgery or having severe aortic or mitral regurgitation; all other patients were considered to have less severe valvulopathy. RESULTS: The proportion with severe valvulopathy increased from 20-66% with increasing fenfluramine dosage from less than or equal to 40 mg/d to greater than or equal to 60 mg/d, Compared with patients taking <40 mg/d fenfluramine, patients taking greater than or equal to 60 mg/d had an adjusted odds ratio of 9.2 (95% confidence interval = 2.1-40.8) for severe valvulopathy, CONCLUSION: Compared to patients with less severe valvulopathy, those with severe valvulopathy were substantially more likely to have taken greater than or equal to 60 mg/d fenfluramine.