OBJECTIVES: Frequently economic evaluations of health technologies incorporate econometric models into the decision making process. CCOHTA published in 1999 a transparent model in ADHD which has been adapted to assess the impact of incorporating parent-rated outcomes using CCOHTA's existing methodology. The adapted model also estimates the incremental impact from Concerta OROS, a new OD formulation of methylphenidate (MPH), used over MPH immediate release (MPH-IR) and behavioural treatment (BT). METHODS: First, the original model was re-constructed and validated to ensure all assumptions and calculations were incorporated correctly. Next, the model was adapted to include the following treatment arms - Concerta OROS 30mg/day OD, MPH-IR 30 mg/day TID, BT. Most assumptions/data from the original model were maintained except for the following: weighted mean difference (WMD) of parent ratings on the Conners IOWA Inattention/Overactivity subscale (IOWA I/O) were used in place of Conners Teacher Rating Scale (CTRS) hyperactivity index; all patients received behavioural interventions for a full year versus 6 months for those non-compliant to treatment; compliance rates were fixed based on literature; outcomes data came from published double blind, double dummy cross-over trial comparing Concerta OROS to MPH-IR to placebo (n=68). Effectiveness was expressed in one point gain in IOWA I/O (=clinically relevant improvement). Analysis was conducted using DATA 3.5 by TREEAge. RESULTS: MPH-IR and Concerta OROS resulted in increases in both annual costs (+$600 CDN, +$713CDN respectively) and effectiveness (+0.71 point gain, +1.44 point gain respectively) compared to BT. Incremental cost-effectiveness ratios were $851/one point gain in IOWA I/O and $496/one point gain in IOWA I/O for MPH-IR and Concerta OROS respectively. CONCLUSIONS: Parent ratings can be adopted within economic models of ADHD. Under model assumptions, using parent generated outcome ratings, a combination of behavioural interventions and Concerta OROS dominated MPH-IR treatment. Further sensitivity analysis and drawbacks will be discussed.