Defining treatment response in gambling disorder

Background: Gambling disorder is a common mental health condition, and a growing cause of concern globally. Despite the availability of well-validated self-report and clinical instruments to measure symptom severity, there has been no study to establish optimal thresholds for determining treatment response based on these measures. Methods: Data from 553 participants (aged 18–65 years) who had participated in previous pharmacological and psychotherapeutic clinical trials for gambling disorder were aggregated. Studies were included that collected Clinical Global Impression Improvement (CGI-I) at end-of-study (reference standard), as well as baseline and end-of-study symptom severity using the Gambling Symptom Assessment Scale (GSAS) and/or the Yale-Brown Obsessive-Compulsive Scale Modified for Pathological Gambling (PG-YBOCS). Receiver Operator Characteristic (ROC) analyses were conducted to identify optimal thresholds for determining treatment response. Results: Greater than 50% improvement in PG-YBOCS and 35% improvement in GSAS were the optimal thresholds for defining treatment response. For the PG-YBOCS, the cutoff had acceptable sensitivity and specificity (85.0%, 83.0%) and area under the curve of 0.904. For the GSAS, the cutoff had acceptable sensitivity and specificity (81.2%, 73.4%), and area under the curve of 0.859. Conclusions: This study provides useful thresholds on two widely used, valid outcome measures for gambling disorder, in terms of determining treatment response or absence thereof. These thresholds may be useful for clinical practice at the level of individual patients, but also for future clinical trials.