Fig 1. PRISMA flow chart.

Our literature search found 368 unique articles and we found another 5 that were referenced in articles. We initially screened articles to check that they used an RCT design, extended the duration of a previous RCT experiment, or performed secondary analysis on a previous RCT. We found that 49 articles met this criterion plus the 5 that we found referenced in other articles. We then read those articles and excluded ones that used a mixed treatment (e.g., IPS plus some other component) or did not report an outcome variable of interest. We excluded 24 articles for these reasons. This left 30 articles in total that we used for analysis.