In a prospective study that sought to longitudinally investigate MMT use among HIV positive IDUs in Canada, Pettes, Wood, Guillemi, Mmath, Montaner and Kerr (2010) showed that MMT use was associated with a reduced likelihood of frequent heroin injection, syringe borrowing, non-fatal overdose, and public injection.[22] Likewise, Corsi, Lehman and Booth (2009) found that spending more time in MMT was a significant predictor of positive outcomes on drug use and HIV risk behaviors.[23] The results underscore the importance of retaining IDUs in MMT in order to maximize their treatment success