ADHD in Adults: A Systematic Review and Meta-Analysis of Prevalence Studies in Outpatient Psychiatric Clinics.

OBJECTIVE

Systematic review and meta-analysis to estimate the pooled prevalence of ADHD in adult attendees of outpatient mental health clinics and to investigate factors influencing prevalence rates.

METHODS

The following were extracted: demographics, design of the study (screening only or two-phase), scales/criteria for diagnosis of ADHD, number of ADHD, and non-ADHD participants.

RESULTS

The pooled prevalence of ADHD from screening studies ( = 9) was 26.7%, (95% CI [17.2-37.4]), ADHD = 1727, No ADHD = 3,578. From studies employing a two-stage design ( = 5), prevalence was 14.61%, CI [10.39-19.41], ADHD = 561, No ADHD = 3,578. Age and gender did not have any significant effect on the estimated prevalence. By contrast exclusion of psychotic disorders lowers prevalence. The screening scale used also influence prevalence rates.

CONCLUSION

Meta-analysis shows high rates of adult ADHD among psychiatric outpatient clinics. Applying DSM-5 criteria increased prevalence rates. More methodologically robust studies, using two-stage design, need to be conducted to help assist in service planning.