Age-, sex-, and stroke type-specific associations of lifestyle factors with 30-day poststroke case-fatality: a nationwide cohort study.

Prior studies have suggested that smoking, alcohol consumption, and living situation may be associated with poststroke mortality, but evidence on how these associations vary by age, sex, and stroke type remains limited. We examined associations of alcohol consumption, smoking, and living situation with 30-day case-fatality in hospitalised patients with ischaemic stroke or intracerebral haemorrhage, stratified by age, sex, and stroke type. This nationwide cohort study included stroke patients admitted between 2015 and 2023 from the Danish Stroke Registry. Thirty-day case-fatality was analysed using Kaplan-Meier and Cox regression stratified by stroke type, age, and sex, with multiple imputation for missing data. Among 94,668 patients (median age 73 years; IQR 64-81 years; 56% male), 83,682 had ischaemic stroke and 10,986 had intracerebral haemorrhage. Among ischaemic stroke patients, high alcohol consumption increased 30-day case-fatality in males ≤ 65 years (≈ 50% higher vs. low consumption), rising to ≈ 75% in those ≤ 56 years. Current smokers were associated with 30-50% higher case-fatality in both sexes aged 66-84 (vs. never smokers). Living alone was associated with increased case-fatality in males, attenuating with age (vs. cohabiting). Among intracerebral haemorrhage patients, high alcohol consumption increased case-fatality in younger males (vs. low consumption), current smokers increased case-fatality in both sexes ≤ 82 years (vs. never smokers), while living situation showed no consistent association. Stratified analyses demonstrate age-, sex-, and stroke type-specific heterogeneity in associations, identifying high-risk subgroups not captured by overall estimates and supporting more granular risk stratification in acute stroke care.