RESUMO
BACKGROUND: Gambling disorder (GD) and substance use disorder (SUD) have mutual impact and each could aggravate the effects of the other. This is the first study on GD among Iranian substance users to develop and validate a GD Screening Questionnaire-Persian (GDSQ-P). METHODS: Iranian male adults (n = 503) with SUDs were recruited via clustered sampling. Problem gambling screening instruments and Diagnostic and Statistical Manual of Mental Disorders-5th Edition (DSM-5) criteria for GD were used to develop the tool which was sequentially assessed for face validity, content validity index (CVI), content validity ratio (CVR), and reliability (Kuder-Richardson coefficient). To establish construct validity, interviews based on DSM-5 as a gold standard method were used. A receiver operating characteristic (ROC) curve was conducted to determine sensitivity and specificity. FINDINGS: After removing items with low CVI values, 27 final items remained in GDSQ-P with impact score greater than 1.5. Card games (33.8%), dice gambling methods (26.6%), betting on sports teams and players (24.1%), and betting on horseback, rooster, pigeon, dog, or other animals (16.7%) were common gambling methods among participants. Overall Kuder-Richardson coefficient was 0.95. Cut-off threshold for GDSQ-P was calculated as 4.5 with 98.9% sensitivity and 98.3% specificity. The interviewers confirmed GD for participants based on DSM-5 as the gold standard. The prevalence of GD among participants was 17.9% based on GDSQ-P and 19.1% based on DSM-5 criteria. CONCLUSION: GDSQ-P is a valid and reliable tool to screen for GD in SUD treatment centers and probably in the general population.