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The risk of intracerebral haemorrhage with smoking. The Melbourne Risk Factor Study Group
A G Thrift1, J J McNeil, G A Donnan
1Department of Epidemiology and Preventive Medicine, Monash Medical School, Alfred Hospital, Vic., Australia. thrift@austin.unimelb.edu.au
Insights
Smoking does not directly increase the risk of primary intracerebral hemorrhage (ICH). However, an interaction between smoking and hypertension significantly elevates ICH risk, particularly in men.
Area of Science:
- Neurology
- Epidemiology
- Public Health
Background:
- Smoking is a known risk factor for various cardiovascular diseases, including some types of stroke.
- The specific relationship between smoking and primary intracerebral hemorrhage (ICH) requires further clarification.
Purpose of the Study:
- To investigate the association between smoking and the risk of primary intracerebral hemorrhage (ICH).
- To explore potential interactions between smoking and other risk factors, such as hypertension, in relation to ICH.
Main Methods:
- A case-control study involving 331 patients with first-episode ICH confirmed by computed tomography.
- Age- and sex-matched community-based controls (n=331) were used for comparison.
- Analysis included assessment of smoking status (current, past), amount smoked, duration, and interaction with hypertension.
Main Results:
- No significant increase in ICH risk was observed directly associated with smoking (odds ratio [OR], 1.07; 95% confidence interval [CI], 0.63–1.81).
- Neither smoking amount nor duration showed a direct association with ICH risk.
- A significant interaction between smoking and hypertension was identified, substantially increasing ICH risk, predominantly in men (OR, 8.13; 95% CI, 2.04–32.42).
Conclusions:
- Smoking alone does not appear to be an independent risk factor for primary intracerebral hemorrhage.
- The combination of smoking and hypertension presents a significantly elevated risk for ICH, especially in males.
- Further prospective studies are warranted to validate this interaction finding.
Abstract:
To determine whether smoking contributes to the risk of primary intracerebral haemorrhage (ICH) a case-control study was carried out on 331 consecutive cases of first-episode ICH as verified by computed tomography. Patients were age- and sex-matched to 331 community-based controls. Unlike other forms of stroke where smoking is an established risk factor, there was no increase in risk of ICH with smoking in this study (odds ratio, OR, 1.07, 95% confidence interval, CI, 0.631.81). Similar ratios were obtained for past and current smokers. Neither the amount smoked nor the duration of smoking were associated with ICH. Further investigation, however, revealed an interaction between smoking and hypertension on the risk of ICH that was similar regardless of the amount of cigarettes currently smoked and was largely seen to be a phenomenon in men (OR 8.13, 95% CI 2.0432.42). This interaction is a new finding, but the post-hoc nature of this analysis requires that it be further tested, preferably in a large prospective study.