Louis Favril

Background Previous meta‐analyses may have overestimated the prevalence of attention‐deficit hyperactivity disorder (ADHD) in prisoners by including data from selected samples. Aims To estimate the prevalence of ADHD in unselected samples of adults in prison and examine potential sources of heterogeneity by meta‐regression and subgroup analyses. Methods We assessed all studies included in a 2018 systematic review for eligibility and updated the literature search to include studies published up to September 2023. Results A total of 11 studies reporting robust diagnostic data on ADHD in 3919 unselected adults in prison were included. In meta‐regression, ADHD prevalence did not differ between men and women but it was significantly higher in studies using a two‐phase design. In random sampling studies, the pooled prevalence of ADHD was 8.3% (95% CI: 3.8–12.8) which was further halved after the removal of an outlier. Conclusion One in 12 adults in prison have been diagnosed with ADHD. Our findings highlight the importance of using clear and consistent inclusion criteria in meta‐analyses of prevalence.