Influence of premorbid factors on survival following subarachnoid hemorrhage

Object. The goal of this study was to explore the relationships between pre morbid patient characteristics, especially cigarette smoking, and the risk of death following subarachnoid hemorrhage (SAH). Methods. A population-based study design was used with multiple overlapping methods of case identification. A strict definition of SAH was used. Relat ionships between patients' age and sex as well as their cigarette smoking a nd hypertension statuses were explored by calculating relative risks (RRs). Confounding effects were examined using logistic regression analysis. The author identified 800 cases in which the patient had experienced his or her first SAH. Seventy-seven percent of cases were verified by review of c omputerized tomography scans, 22% by autopsy, and 1% by lumbar puncture. A prior history of hypertension had no effect on the risk of mortality. There was a higher case mortality rate in female patients than in male patients, but this did not reach statistical significance. The RR of death at 30 day s post-SAH for patients older than 60 years compared with those who were yo unger was 2.95 (95% confidence interval [Cl] 2.18-3.97). The RR of death at all time intervals was lower for smokers than for nonsmokers (smokers/nons mokers RR 0.47 [95% CI 0.32-0.69] at 7 days). The protective effect of smok ing diminished on Day 3 post-SAH and increased again on Day 7. Conclusions. Advanced age is an important determinant of survival following SAH. Smoking appears to have a protective effect. The author presents evid ence indicating that increased vasospasm in smokers may reduce the severity of the initial hemorrhage.