Predictors of treatment outcome in adults with ADHD treated with OROS<ce:sup loc=post>®</ce:sup> methylphenidate
BACKGROUND
We conducted a post-hoc analysis of the Long-Acting MethylpheniDate in Adult attention-deficit hyperactivity disorder (LAMDA) study to investigate predictors of response in adults with ADHD randomly assigned to Osmotic Release Oral System (OROS)(®)-methylphenidate hydrochloride (MPH) 18, 36 or 72 mg or placebo.


METHODS
LAMDA comprised a 5-week, double-blind (DB) period, followed by a 7-week, open-label (OL) period. A post-hoc analysis of covariance and a logistic regression analysis were undertaken to detect whether specific baseline parameters or overall treatment compliance during the double-blind phase contributed to response. The initial model included all covariates as independent variables; a backward stepwise selection method was used, with stay criteria of p<0.10. Six outcomes were considered: change from baseline CAARS:O-SV (physician-rated) and CAARS:S-S (self-report) scores at DB and OL end points, and response rate (≥30% decrease in CAARS:O-SV score from baseline) and normalization of CAARS:O-SV score at DB end point.


RESULTS
Taking into account a significant effect of OROS(®)-MPH treatment versus placebo in the original analysis (p≤0.015), across the outcomes considered in this post-hoc analysis, higher baseline CAARS scores were most strongly predictive of superior outcomes. Male gender and lower academic achievement were also predictive for improved results with certain outcomes.


CONCLUSIONS
Several baseline factors may help to predict better treatment outcomes in adults receiving OROS(®)-MPH; however, further research is required to confirm these findings and examine their neurobiological underpinnings.