Co-Use of Tobacco Products and Cannabis Is Associated with Absenteeism and Lower Grades in California High School Students.

OBJECTIVE: To examine the association between co-use of commercial tobacco product (hereafter referred to as tobacco) and cannabis with educational outcomes among high school students. STUDY DESIGN: We analyzed high school student data from the 2021-2022 California Healthy Kids Survey (n = 287 653). Current (past-month) or ever tobacco and cannabis use was categorized as co-use, only tobacco or cannabis, or neither. Two self-reported educational outcomes were examined: absenteeism and grades. Adjusted logistic and linear regression models were used to examine the association between tobacco/cannabis use and absenteeism or grades, respectively. Estimates were adjusted for individual, peer, and school covariates, and clustering within schools. RESULTS: Current co-use of tobacco and cannabis was more than double the use of only tobacco (3.7% vs 1.7%) and similar to only cannabis (3.7%). Almost 18% of students reported absenteeism. Compared with students who used neither substance, students with current co-use had greater odds of absenteeism (aOR 1.41, 95% CI 1.33-1.49) and lower grades (ß = -0.87, 95% CI -0.92 to -0.82). Compared with students using tobacco alone, students with co-use also had a significant elevated odds of absenteeism (aOR 1.19, 95% CI 1.10-1.29) and lower grades (ß = -0.39, 95% CI -0.46 to -0.32). Similar results were found for students who ever used tobacco and cannabis. CONCLUSIONS: California youth who co-use tobacco and cannabis were most likely to have absenteeism and lower grades. Comprehensive efforts to prevent or reduce youth substance use may improve educational outcomes.