We used Cox proportional hazard methods to estimate the risk of onset of alcohol use disorder as a function of marital status, which was included in the model as a time-dependent covariate. The outcome variable was time to onset of alcohol use disorder after age 18, and we censored at death, end of marriage, migration, or end of follow-up (2011), whichever came first. Subjects with an onset of alcohol use disorder prior to age 18 were also censored; they are uninformative in our analyses because marriage prior to age 18 is illegal in Sweden. We adjusted for year of birth and parental education. To account for early deviant behavior, we included registration of criminal behavior or drug abuse through age 18. We investigated whether lifetime registration for alcohol use disorder in the spouse affected the association with marital status, and, finally, we explored whether a higher genetic risk modified the marital impact. To test for gender differences, we constructed a joint model including both sexes and allowing all covariates to differ by gender by including the relevant interactions in the model.
