Use of dexfenfluramine, fenfluramine and phentermine and the risk of stroke

Aims To estimate the incidence of newly diagnosed idiopathic stroke among u sers of fenfluramine, dexfenfluramine and phentermine compared to obese non users. Methods We conducted a cohort study with nested case-control analysis utili zing data from the General Practice Research Database in the UK. Eight thou sand four hundred and twenty-three subjects aged 69 years or less at the st art of follow-up were exposed to at least one of the three study drugs and 17 225 similarly obese subjects were not exposed to any of the study drugs. Results We identified 45 incident cases of idiopathic CVA in this cohort of subjects. The incidence of CVA among all current users of a diet drug was 1.3/1000 person-years (95% CI 0.5, 3.5). The incidence for current fenflura mine users (n=2) was 2.6/1000 person-years (95% CI 0.7, 9.6), for current d exfenfluramine users (n=1) 1.1/1000 person-years (95% CI 0.3, 3.8), and for current phentermine users 0/1000 person-years (95% CI 0.0, 12.9). The inci dence in obese nonusers was 0.6/1000 person-years (95% CI 0.4, 0.9). The ad justed matched odds ratio (OR) for thrombotic stroke from the case-control analysis comparing current use of a diet drug to nonuse was 2.4 (95% CI 0.6 , 9.1). There was only one exposed subject among seven who had haemorrhagic stroke. Conclusions The incidence of CVA in generally young obese subjects during u se of fenfluramine, dexfenfluramine or phentermine is low. Although we foun d an OR of 2.4 comparing users of any of the anorexiants with nonusers, thi s is based on only three exposed cases and the confidence limits are wide. We conclude that our study does not support a substantial increased risk of stroke attributable to the use of fenfluramine, dexfenfluramine or phenter mine.