There are several limitations to our study. First, VIDUS and ACCESS are not random samples and cannot be presumed to be wholly representative of the PWUD population in Vancouver or elsewhere. Second, MMT discontinuation events and reasons for discontinuation were self-reported by study participants and may be impacted by recall bias. Third, the duration of the MMT before it was discontinued could not be determined based on the nature of the study. Fourth, our statistical methods considered associations between MMT discontinuation and various independent variables over time. The exact temporal relationship between the outcome of interest and the independent variables cannot be ascertained and therefore this study does not allow for a thorough investigation of causal relationships. In sub-analyses, not all study participants reported a discontinuation reason, and reported reasons were not studied qualitatively.
