NATURAL CLASSES OF TREATMENT RESPONSE

This study examines an approach to identifying patterns of treatment r esponse over time. Treatment response profiles are identified by clust er analyzing a repeated measure of patient performance collected at in tervals during treatment. The procedure is demonstrated in Study 1 usi ng monthly urinalysis results of 103 patients entering methadone maint enance treatment. The internal, external, and face validities of deriv ed treatment response profiles are evaluated. A logistic regression mo del predicting treatment response is then constructed from intake vari ables found to correspond with the treatment response profiles. Study 2 replicates the procedures on an independent sample. Treatment respon se profiles facilitate the analysis of treatment response offering adv antages over common measures of treatment outcome, such as performance at follow-up, change in performance from treatment entry to follow-up , or performance summed across treatment.