... Krabbenborg Regarding outcome variables in the included studies, seven studies assessed substance use behaviours such as substance craving, addiction severity, drug dependency, and drinking status (Chang et al., 2010;Garland et al., 2016;Malte et al., 2017;Reback et al., 2010;Salem et al., 2017;Toro et al., 1997;Upshur et al., 2015). Depression was assessed in five studies (Garland et al., 2016;Guo et al., 2016;Himle et al., 2014;Krabbenborg et al., 2017;Medalia et al., 2017), anxiety in five studies (Chang et al., 2010;Garland et al., 2016;Himle et al., 2014;Krabbenborg et al., 2017;Medalia et al., 2017), mental health status in four studies (Chang et al., 2010;Guo et al., 2016;Malte et al., 2017;Upshur et al., 2015), PTSD symptoms in three studies (Garland et al., 2016;Held & Owens, 2015;Lester et al., 2007), psychological distress in two studies (Medalia et al., 2017;Toro et al., 1997), self-efficacy in two studies (Guo et al., 2016;Toro et al., 1997), and quality of life in two studies (Krabbenborg et al., 2017;Shern et al., 2000). ...