Mobile Apps to Reduce Tobacco, Alcohol, and Illicit Drug Use: Systematic Review of the First Decade.

Although most app interventions were associated with reductions in problematic substance use, less than one-third were significantly better than the comparison conditions at post treatment. A total of 5 out of the 6 apps that reported intervention effects targeted alcohol (of those, one targeted alcohol and illicit drugs and another alcohol and tobacco) and 1 targeted tobacco. Moreover, 3 out of 6 apps included feedback (eg, personalized) and 2 had high risk of bias, 1 some risk, and 3 low risk. All 6 apps included interventions of 6 weeks or longer. Common study limitations were small sample sizes; risk of bias; lack of relevant details; and, in some cases, poorly balanced comparison conditions. Appropriately powered trials are required to understand which app interventions are most effective, length of engagement required, and subgroups most likely to benefit. In sum, evidence to date for the effectiveness of apps targeting problematic substance use is not compelling, although the heterogeneous comparison conditions and trial designs across studies limit the ability to compare efficacy between apps. We discuss potential approaches that can help ascertain whether the promise of mobile app interventions for problematic substance use can be fulfilled.