School performance and alcohol-related disorders in early adulthood: a Swedish national cohort study

Background Alcohol misuse is an important global health determinant and a major contributor to health inequalities. We aimed to investigate the association between school performance and alcohol-related disorders in early adulthood in a longitudinal register-based national cohort study. Methods We followed a register-based national cohort of Swedish citizens born 1973-1984 (N = 948 440) from compulsory school graduation at age 15-16 to 2009. We divided the population into five groups: high school marks (> mean+1 SD); high average (between mean and mean - 1 SD); low average (between mean and mean - 1 SD); low (< mean - 1SD); and missing. Cox proportional hazard models were used to investigate the relation between school marks at time of graduation and hospital care for alcohol-related disorders in early adulthood. Results There was a steep gradient in the risk of alcohol-related disorders related to school performance. In comparison with peers in the top category of school marks, students with low marks had adjusted hazard ratios of 8.02 [95% confidence interval (CI) 7.20 to 8.91], low average 3.02 (2.72 to 3.35) and high average 1.55 (1.39 to 1.73). The risk associated with low school marks was stronger in the male population and in the group from high socioeconomic background. Conclusions The study demonstrated a strong graded relation between low school performance and alcohol-related disorders in young adulthood. School performance should be taken into account when developing prevention programmes/policies targeting alcohol misuse among teenagers and young adults, especially if the aim is to reach high-risk groups.