<b>Substance Use Disorder Severity Among Patients with and Without ASRS-Based Probable Adult ADHD in Rehabilitation Settings in Nairobi, Kenya</b>

Adult Attention-Deficit/Hyperactivity Disorder (ADHD) frequently co-occurs with Substance Use Disorders (SUDs) and has been associated with greater substance-related severity. Evidence comparing SUD severity according to ADHD screening status among treatment-seeking adults in Kenya remains limited. A cross-sectional analytical study was conducted among adults aged 18–65 years receiving SUD treatment in six rehabilitation centres in Nairobi, Kenya. Of 390 eligible patients, 322 participated (82.6%). Adult ADHD was screened using the Adult ADHD Self-Report Scale Version 1.1 (ASRS v1.1), while alcohol- and drug-related severity were assessed using the Alcohol Use Disorders Identification Test (AUDIT) and Drug Abuse Screening Test-10 (DAST-10), respectively. Mean severity scores were compared between participants with and without ASRS-based probable adult ADHD, with mean differences, 95% confidence intervals (CIs), and Hedges’ g reported. Ninety participants (28.0%) met the study criteria for ASRS-based probable adult ADHD. Mean AUDIT scores were higher among participants with probable ADHD than among those without probable ADHD (28.81 vs. 21.88; mean difference = 6.93, 95% CI [4.52, 9.34]; Hedges’ g = 0.70; p < .001). Mean DAST-10 scores were also higher (6.59 vs. 4.09; mean difference = 2.50, 95% CI [1.77, 3.23]; Hedges’ g = 0.77; p < .001). ASRS-based probable adult ADHD was associated with greater alcohol- and drug-related SUD severity among adults receiving treatment in Nairobi. The findings support further evaluation of the clinical utility of ADHD screening and comprehensive assessment within Kenyan SUD treatment settings.