Objective: Relative age refers to a difference in age between peers in the same academic year. Although younger age of alcohol use is associated with a higher risk of lifetime problematic alcohol use, the potential effects of relative age are poorly understood. We hypothesized that a younger relative age would be associated with a younger chronological age of testing positive for alcohol in a medical setting. Methods: Problematic alcohol use was operationalized and identified as a positive alcohol test (PAT) in a medical setting. This was a retrospective population study of all 12 to 18-year-old residents (n = 4610) of Olmsted County, Minnesota (USA), who were tested for alcohol in a medical care setting from 1998 through 2016. Cox regression models examined the relationship between relative age and the age at testing positive for alcohol. Results: Relative age was not associated with age at first PAT. Results remained nonsignificant after stratifying by gender, and after adjusting for race, number of nonalcohol-related psychiatric comorbidities, and type of alcohol testing. Conclusions: The results did not support a relative age effect as a risk factor for alcohol use in adolescents in Olmsted County, Minnesota. These results contrast with findings from previous studies on this topic, which suggested older relative age increases risk of alcohol use in adolescence.
Keywords: adolescent; alcohol abuse; alcohol use disorder; relative age; substance use.