Lifetime Cannabis Use and Incident Hypertension: The Coronary Artery Risk Development in Young Adults (CARDIA) Study.

BACKGROUND Observational evidence investigating associations between cannabis use and hypertension is inconsistent. METHODS The association between cumulative lifetime cannabis use (cannabis-years) and incident hypertension was examined over 35 years in a sample of CARDIA study (Coronary Artery Risk Development in Young Adults) participants free of hypertension at baseline. Marginal structural models with inverse probability weighting were used to adjust for potential time-dependent confounding and censoring. Hazard ratios and 95% CIs were estimated using Cox proportional hazards regression. Sensitivity analyses included modeling cannabis-years using restricted cubic splines, stratifying the primary analyses by sex, race, alcohol and cigarette smoking, and evaluating an additional exposure measure (days of use in the past month). RESULTS The analytic sample consisted of 4328 participants at baseline and 64.9% (n=2810) at year 35. Median cannabis-years increased minimally and remained low across visits: 0.0 (Q1-Q3, 0.0-0.3) at baseline and 0.2 (Q1-Q3, 0.0-0.7) by year 35. There were 2478 cases of incident hypertension over 88 292 person-years (28.1 cases per 1000 person-years). Cannabis-years were not significantly associated with incident hypertension (adjusted hazard ratio, 0.99 [95% CI, 0.97-1.00]; P=0.18). The association remained unchanged in sensitivity analyses. CONCLUSIONS In a cohort of Black and White young adults with 35 years of follow-up, no association was found between cumulative lifetime use of cannabis and risk of incident hypertension. This finding was robust to restricted cubic spline analyses, analyses stratified by sex, race, alcohol use and tobacco cigarette smoking, and an additional measure of exposure (days of use in the past month).