Risk of valvular heart disease associated with use of fenfluramine Paul

Background: Estimates of excess risk of valvular heart disease among prior users of fenfluramine and dexfenfluramine have varied widely. Two major forms of bias appear to contribute to this variability and also result in a systematic under-estimation of risk. The first, a form of nondifferential misclassification, is the result of including background, prevalent cases among both exposed and unexposed persons in calculations of risk. The second bias results from not considering the relatively short duration of exposure to drugs. Methods: We examined data from all available echocardiographic studies reporting the prevalence of aortic regurgitation (AR) and mitral regurgitation (MR) among persons exposed to fenfluramine or dexfenfluramine and a suitable control group. We also included one study in which previously existing AR or MR had been excluded. We corrected for background prevalent cases, estimated incidence rates in unexposed persons, and performed a person-years analysis of apparent incidence rates based on exposure time to provide an unbiased estimate of relative risk. Results: Appearance of new AR was strongly related to duration of exposure (R2 = 0.75, p < 0.0001). The summary relative risk for mild or greater AR was 19.6 (95% CI 16.3 – 23.5, p < 0.00001); for moderate or greater MR it was 5.9 (95% CI 4.0 – 8.6, p < 0.00001). Conclusion: These findings provide strong support for the view that fenfluramine and dexfenfluramine are potent causal factors in the development of both aortic and mitral valvular heart disease. Background Since the initial report by Connolly, et al [1] of valvulopathy in women taking the combination of fenfluramine and phentermine (fen-phen), controversy has surrounded the issue of associated risk. Initial reports of remarkably high prevalence of aortic and mitral regurgitation (AR and MR) as assessed by echocardiography in five separate populations [2] were subsequently supported by most [3–5] but not all investigators [6]. These uncontrolled reports were soon followed by a series of studies in which prevalence of echocardiographically-defined AR and MR were assessed in persons who had taken fenfluramine, dexfenfluramine, phentermine, or combinations of these medications and compared to unexposed, matched control populations [7–15]. The most recent of these studies found 30% of persons currently taking fenfluramine or dexfenfluramine had mild or greater AR or moderate or greater MR, similar to the very high prevalence reported in Published: 11 June 2003 BMC Cardiovascular Disorders 2003, 3:5 Received: 24 January 2003 Accepted: 11 June 2003 This article is available from: http://www.biomedcentral.com/1471-2261/3/5 © 2003 Hopkins and Polukoff; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.