Correlation of symptomatic improvements with functional improvements and patient-reported outcomes in adults with attention-deficit/hyperactivity disorder treated with OROS methylphenidate

Objectives. To evaluate correlations between symptom severity and daily functioning in adults with ADHD. Methods. In the 5-week, double-blind LAMDA study, 401 adults with ADHD were randomly assigned to Osmotic-Release Oral System (OROS) methylphenidate (MPH) 18, 36 or 72 mg/day, or placebo. The primary variable – investigator-rated Conners’ Adult ADHD Rating Scale (CAARS:O-SV) – has been presented previously. Secondary endpoints included the self-reported version of CAARS (CAARS-S:S) and Clinical Global Impression – Severity (CGI-S). Daily functioning and quality of life were assessed using the Sheehan Disability Scale (SDS) and Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q). Relationships between symptom and functional outcomes were evaluated in post-hoc Pearson partial correlation, multivariate regression and mediator analyses. Results. Improvements in CAARS-S:S, CGI-S and SDS scores were significantly greater in each OROS MPH arm versus placebo (P < 0.01 for all comparisons). Correlations between symptom and functioning scores were significant for all comparisons (P < 0.0001). In regression analyses, CAARS Hyperactivity/Impulsivity subscale and CGI-S were correlated with SDS (P < 0.05). CAARS Inattention was correlated with the SDS Family Life domain (P < 0.05). In a mediator analysis, the impact of treatment on SDS scores was fully mediated by improvement in CAARS:O-SV score. Conclusions. OROS MPH 18–72 mg/day was associated with significant improvements in ADHD symptoms, which correlated with improved daily functioning and health-related quality of life.