Background Substantial research suggests that the risk of substance misuse is higher among individuals who remain unmarried or experience marital dissolution, whereas marriage tends to be protective. However, few studies have considered the role of substance misuse for transitions between discrete marital status categories. The current study aims to estimate associations between substance misuse and marital status transitions from ages 20–66.

Methods Our study population was a national Swedish cohort born in 1953 (n=71 901), followed from 1973 to 2019. Annual marital status and hospitalisation records for substance misuse were derived from the Total Population and National Patient registers, respectively. We used a five-state multistate model to estimate associations between substance misuse and marital status transitions—the state space included never married, married, divorced and widowed with death as the absorbing state. We further used fixed-effect models to estimate the effects of substance misuse on transitions out of marriage.

Results Findings suggested that individuals’ substance misuse was associated with an increased risk of transitioning from married to divorced (HR=3.54, 95% CI 3.40 to 3.69) or widowed (HR=1.71, 95% CI 1.46 to 2.01), and transitioning to death from all states. Substance misuse was also negatively associated with transitioning from never married to married (HR=0.59, 95% CI 0.57 to 0.61), and into remarriage after divorce (HR=0.86, 95% CI 0.80 to 0.92). The fixed-effect results suggested that substance misuse increased the risk of transitioning to divorce and widowhood, net of sociodemographic characteristics.

Conclusion Substance misuse is associated with an increased risk of marital dissolution and death when accounting for nearly 50 years of marital biographies.