BackgroundBecause of the broad range of activities involved and high variance in clients’ needs, it is challenging to measure the actual dose of case management in order to assess quality and manage outcomes.ObjectiveThe purpose of this research is to evaluate the impact of intervention dosage on client outcomes in different case management models within substance abuse treatment.MethodA descriptive and repeated measures analysis from a clinical trials data set measured the dosage of case management and evaluated impact on client outcomes. A sample of 598 clients from a substance abuse treatment facility was randomized into one of four groups, assessed at intake and then followed for 1 year. Three groups received a form of case management as an intervention (n= 437), and all clients received drug treatment.ResultsClients who engaged (actively participated) in case management were less likely to have legal and family issues but more likely to have a chronic medical condition at baseline. Dosage factors differed significantly across treatment conditions. In general, dose was significantly related to outcomes in the legal and family domains.ConclusionsAlthough complex, case management intervention dosage can be measured using the model presented. Dosage determination aids cost-effective initiatives. Further research is needed to specify intervention protocols.