Impact of smoking cessation on the risk of subarachnoid haemorrhage: a nationwide multicentre case control study
- 1Department of Neurology, Seoul National University Hospital, Seoul, Republic of Korea
- 2Clinical Research Centre for Stroke, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
- Correspondence to Dr S-H Lee or Dr B-W Yoon, Department of Neurology, Seoul National University Hospital, 28 Yeongeon-dong, Jongno-gu, Seoul 110-744, Republic of Korea; or
Contributors S-HL and B-WY devised the original study concept and design. BJK and W-SR participated in the acquisition of the data. CKK and BJK performed the statistical analyses. S-HL and B-WY made intellectual contributions. CKK and S-HL interpreted the results and wrote the manuscript.
- Received 16 February 2012
- Revised 15 June 2012
- Accepted 10 July 2012
- Published Online First 30 August 2012
Background and purpose Subarachnoid haemorrhage (SAH) is the most devastating cerebrovascular disease. Cigarette smoking is one of the established risk factors for SAH, but the risk of SAH has not been properly elucidated in relation to smoking cessation.
Methods We performed a nationwide multicentre case control study involving 33 hospitals in Korea. A total of 426 SAH cases and 426 age and sex matched controls were enrolled. We obtained detailed information on lifestyle, medical history and, in particular, smoking habits from participants using structured questionnaires.
Results 148 SAH patients (37.4%) were current smokers compared with 103 (24.2%) controls, giving an adjusted OR of 2.84 (95% CI, 1.63 to 4.97) after controlling for possible confounders. Based on cumulative dose of smoking (pack years), the risk of SAH was found to increase in a dose–responsive fashion. Smoking cessation (≥5 years) caused a reduction in SAH to 59% (p<0.05). However, participants with a history of heavy smoking (≥20 cigarettes per day) had a 2.3 times increased risk of SAH compared with participants who had never smoked (p<0.05).
Conclusions We have demonstrated that cigarette smoking increases the risk of SAH, but smoking cessation decreases the risk in a time dependent manner, although this beneficial effect may be diminished in previous heavy smokers. To forestall tragic SAH events, our results call for more global and vigorous efforts for people to stop smoking.
Funding This work was supported by grants from the Korean Health Technology R&D Project, Ministry of Health and Welfare, Republic of Korea (A100331, A102065 and A111014). The funding organisation had no role in the design, conduct or analysis of this study, or in the preparation of this report.
Competing interests None.
Ethics approval Ethics approval was provided by Seoul National University Hospital.
Provenance and peer review Not commissioned; externally peer reviewed.