RESUMO
INTRODUCTION: Approximately 5% of the global population used an illicit drug in 2013. Regarding licit drugs, alcohol is responsible for the occurrence of approximately 200 diseases, among them depression. In addition to health impairments, alcohol is also implicated in many acts of violence. This study aimed to measure the properties of the Rasch model of the Portuguese version of the Global Appraisal of Individual Needs-Short Screener based on evidence obtained during care for users of alcohol and other drugs. METHOD: To collect the data, 128 interviews were held at the Psychosocial Care Center for Alcohol and Other Drugs in the state capital, during which the scale was applied. RESULTS: The Rasch model revealed that the subscales of the instrument were appropriate, with all items having mean infit and outfit values from 0.5 to 1.5, considered optimal for measurement. There was no evidence of differential performance for gender. Substance use and crime and violence items presented redundancy for severity measures. CONCLUSION: Given the need for validated instruments for use in Brazil, it is encouraging that the Portuguese version of the scale was valid for the Rasch model. The results are consistent with studies using the other American, Brazilian, and Canadian versions of the instrument.