Drug-induced progressive multifocal leukoencephalopathy: a case/noncase study in the French pharmacovigilance database.

Progressive multifocal leukoencephalopathy (PML) is an often fatal demyelinating disease of the central nervous system. As effective treatment is unavailable, identification of all drugs that could be associated with PML is essential. The objective of this study was to investigate the putative association of reports of PML and drugs. We used the case/noncase method in the French PharmacoVigilance database (FPVD). Cases were reports of PML in the FPVD between January 2008 and December 2015. Noncases were all other reports during the same period. To assess the association between PML and drug intake, we calculated an adverse drug report odds ratio (ROR) with its 95% confidence interval. We have studied the delay of onset of PML for each drug concerned. Among the 101 cases of PML, 39 drugs were mentioned as suspect. The main therapeutic classes suspected with significant ROR were antineoplastic agents (n = 85), immunosuppressants (n = 67), and corticosteroids. A latent interval from the time of drug initiation to the development of PML is established: the median time to onset was 365 days (123-1095 days). The onset of PML is highly variable and differs among drug classes [from 1 to 96 months (IQR: 39.0-126)]. An association between PML and some immunosuppressant drugs was found as expected, but also with antineoplastic agents and glucocorticoids. An important delay of PML onset after stopping treatment is suspected and should alert prescribers. Prescribers but also patients should be informed about the potential associations with all these drugs. Monitoring could be necessary for many drugs to early detect PML.