Differential Impact of Smoking on Intracerebral Hemorrhage Based on Cerebral Microbleed Status: A Case-Control Study

BackgroundWhile smoking is a major cause of cardiovascular diseases, its association with intracerebral hemorrhage (ICH) remains controversial. Cerebral microbleeds (CMBs) serve as an imaging indicator of ICH, yet ICH can occur independently of CMBs, suggesting distinct underlying mechanisms. We investigated the impact of smoking on ICH after stratifying individuals by CMB presence or absence. MethodsWe conducted a retrospective case-control study and enrolled patients with ICH as their first stroke and controls with non-stroke neurological conditions admitted to our center between 2017 and 2021. The participants were classified by CMB presence on magnetic resonance imaging and smoking status (current/past/never). We performed multivariable logistic regression analysis to assess the association between smoking and ICH, stratified by CMB status. We also assessed whether smoking cessation was linked to a lower ICH risk than current smoking, specifically among past smokers stratified by the duration of cessation. ResultsWe analyzed 487 patients with ICH (median age 70.0 years, interquartile range[IQR] [58.0-81.0], 41.5% female, 53.6% with CMBs) and 322 controls (median age 71.0 years, IQR [58.8-79.0], 47.5% female, 13.4% with CMBs). In the individuals without CMBs, current smoking was more frequently observed in patients with ICH than in controls (25.7% vs. 14.0%, p<0.001) and was independently associated with ICH following adjustment for potential confounders (adjusted odds ratio[aOR] 1.84, 95% confidence interval[CI] 1.02-3.31, p=0.042). Long-term smoking cessation (>10 years) was associated with a lower ICH risk than current smoking (aOR 0.31, 95%CI 0.14-0.67, p=0.003), while short-term cessation ([&le;]10 years) showed no significant difference. The individuals with CMBs demonstrated no significant association between smoking status and ICH. ConclusionsCurrent smoking is significantly associated with ICH in individuals without CMBs but not in individuals with CMBs. Long-term smoking cessation might mitigate ICH risk in individuals without CMBs, emphasizing early smoking cessation as a preventive strategy. Assessing smoking history may aid in identifying those at ICH risk.