Cigarette smoking, alcohol use, and subarachnoid hemorrhage.

TLDR

Subarachnoid hemorrhage remains a devastating disease. The study aimed to identify etiologic risk factors that could enable prevention of subarachnoid hemorrhage. A population‑based case‑control study in King County matched each case to two controls, collected standardized interviews, and used conditional logistic regression to analyze risk factors. Current heavy smokers had an 11.1‑fold increased odds of subarachnoid hemorrhage, light smokers 4.1‑fold, and former smokers 1.8‑fold; risk peaked within 3 hours of smoking, and heavy alcohol use (≥2 drinks/day) was associated with a 2.2‑fold increase, with associations unchanged after adjustment.

Abstract

Subarachnoid hemorrhage remains a devastating disease. Identification of etiologic risk factors would allow the possibility of prevention.We conducted a population-based case-control study in King County, Washington. Patients whose bleeds originated from a source other than an aneurysm were excluded. Two age- and gender-matched control subjects were identified for each case through random digit telephone dialing. A standardized in-person interview was conducted with the patient whenever possible, a proxy respondent for the case in all instances, the two control subjects, and their proxies. Analyses involved conditional logistic regression taking into account matching on age, gender and respondent type.Over 2 years, 169 cases were identified, and 149 participated in the case-control study. Compared with those who never smoked, the odds ratio for current heavy smokers (greater than 20 cigarettes/day) was 11.1 (95% confidence interval [CI], 5.0-24.9); for current light smokers (less than or equal to 20 cigarettes/day), 4.1 (95% CI, 2.3-7.3); and for former smokers, 1.8 (95% CI, 1.0-3.2). The risk associated with smoking was greatest in the 3 hours after a cigarette (odds ratio [OR] = 7.0; 95% CI, 3.7-13.1) and then fell, not reaching the risk in those who had never smoked until more than 10 years had passed since the last cigarette. Heavy alcohol use (greater than 2 drinks/day) was also associated with bleeds (OR = 2.2; 95% CI, 0.9-5.1, after adjusting for smoking status). These associations were not substantially altered after adjusting for several possible confounding factors, including a history of hypertension.Cigarette smoking and heavy alcohol use are associated with the occurrence of subarachnoid hemorrhage.