It is well demonstrated that longer-term (i.e. six months or greater) retention on MMT helps prevent relapse to illicit opioid use (Sees et al., 2000). In addition, it has been shown that individuals who discontinue MMT are at increased risk for fatal overdose (Davoli et al., 2007) and all-cause mortality (Cornish, Macleod, Strang, Vickerman, & Hickman, 2010; Cousins et al., 2016). However, it is estimated that between 46 and 65% of patients who initiate MMT discontinue within the first year and relapse to opioid use (Magura, Nwakeze, & Demsky, 1998; Nosyk, Marsh, Sun, Schechter, & Anis, 2010; Reisinger et al., 2009). Retention on MMT, and prevention of harms associated with relapse to illicit opioid use, therefore remain ongoing challenges.
