Differential Item Functioning Analysis of the CUDIT and Relations With Alcohol and Tobacco Use Among Men Across Five Ethnic Groups: The HELIUS Study

Cannabis use has been rising despite recognition of the negative consequences associated with heavy use. The severity of these consequences has been shown to differ across racial/ethnic groups, even when controlling for consumption levels. The present study conducted an item response theory (IRT) analysis of the Cannabis Use Disorders Identification Test (CUDIT) to better understand the patterns of problematic cannabis use and their relation with other substance use across ethnic groups in the Healthy Life in an Urban Setting (HELIUS) study. CUDIT responses from 1,960 cannabis-using African Surinamese, South-Asian Surinamese, Dutch, Moroccan, and Turkish ethnic origin participants were used to test for differential item functioning (DIF) within an IRT framework. After restricting the sample to men because of low frequency of use among women, several instances of uniform DIF were identified. Multiple-group IRT analysis yielded a harmonized cannabis use phenotype that was used to estimate ethnic group differences in problematic cannabis use and its relation to alcohol and tobacco co-use. These analyses suggested that cannabis users from certain ethnic minority groups experienced higher rates of problematic use than the majority group despite lower rates of cannabis use. Further, cannabis and tobacco use were positively related across groups, whereas only ethnic minority groups showed a positive relation between cannabis and alcohol use. These results demonstrate the importance of accounting for DIF when examining group differences in problematic cannabis use, and support prior evidence suggesting that certain ethnic minority groups may be more likely to experience problematic cannabis use and alcohol co-use relative to the majority group.