Approaches to denote treatment outcome: Clinical significance and clinical global impression compared

The authors of a previous study proposed a statistically based approach to denote treatment outcome, translating pretest and posttest scores into clinically relevant categories, such as recovery and reliable improvement. We assessed the convergent validity of the Jacobson-Truax (JT) approach, using T-score based cutoff values, with ratings by an independent evaluator.

Pretest and retest scores on the Brief Symptom Inventory (BSI) and clinical global impression improvement (CGI-I) ratings were collected repeatedly through routine outcome monitoring from 5,900 outpatients with common mental disorders. Data were collected in everyday practice in a large mental health care provider.

Continuous pretest-to-retest BSI change scores had a stronger association with CGI-I than the categorical variable based on JT. However, JT categorization and improvement according to CGI converged substantially with association indices (Somers' D) ranging from D = .50 to .56. Discordance was predominantly due to a more positive outcome according to JT than on CGI-I ratings.

Converting continuous outcome variables into clinically meaningful categories comes at the price of somewhat diminished concurrent validity with CGI-I. Nevertheless, support was found for the proposed threshold values for reliable change and recovery, and the outcome denoted in these terms corresponded with CGI improvement for most patients.