Table 2. Univariable and multivariable Cox proportional hazards regression analysis of predictors of incident aneurysmal subarachnoid haemorrhage.

	Univariable	Multivariable*
Predictor	HR (95% CI)	HR (95% CI)
Female sex	1.50 (1.29 to 1.75)	0.40 (0.14 to 1.12)
Age per year	1.03 (1.02 to 1.04)	1.01 (1.00 to 1.03)
Family history of stroke	1.26 (1.08 to 1.47)	1.14 (0.99 to 1.31)
Hypertension	1.33 (1.15 to 1.54)	1.45 (1.15 to 1.84)
Smoking status
Never smoking	Reference
Former smoking	1.07 (0.91 to 1.26)	1.13 (0.87 to 1.47)
Current smoking	2.14 (1.76 to 2.60)	1.70 (1.22 to 2.37)
Hypercholesterolaemia	1.05 (0.86 to 1.27)	0.98 (0.79 to 1.21)
Regular physical activity	0.90 (0.77 to 1.06)	1.02 (0.88 to 1.18)
Diabetes mellitus	0.88 (0.61 to 1.26)	0.70 (0.47 to 1.06)
Alcohol consumption
Never	1.56 (1.23 to 1.98)	1.41 (1.07 to 1.85)
On special occasions	Reference
Daily or almost daily	1.14 (0.95 to 1.36)	1.13 (0.88 to 1.45)
Educational attainment
Low	1.29 (1.07 to 1.56)	1.05 (0.88 to 1.24)
Intermediate	Reference
High	0.75 (0.63 to 0.89)	0.84 (0.72 to 0.98)
Interactions
Former smoking * never alcohol consumption	1.32 (0.78 to 2.24)	1.32 (0.84 to 2.10)
Former smoking * daily alcohol consumption	0.93 (0.62 to 1.40)	0.92 (0.64 to 1.31)
Current smoking * never alcohol consumption	0.44 (0.19 to 1.00)	0.47 (0.23 to 0.98)
Current smoking * daily alcohol consumption	0.97 (0.61 to 1.54)	1.02 (0.68 to 1.54)
Regular physical activity * hypercholesterolaemia	0.75 (0.48 to 1.19)	0.68 (0.44 to 1.04)
Regular physical activity * DM	1.68 (0.79 to 3.58)	1.93 (0.96 to 3.89)
Female sex * age per year	1.02 (1.00 to 1.04)	1.03 (1.01 to 1.04)
Female sex * hypertension	0.82 (0.60 to 1.13)	0.75 (0.56 to 1.00)
Female sex * former smoking	0.82 (0.58 to 1.15)	0.86 (0.63 to 1.16)
Female sex * current smoking	1.45 (0.96 to 2.20)	1.54 (1.06 to 2.22)

^*The initial regression coefficients were corrected for overfitting with a shrinkage factor of 0.88.

.DMdiabetes mellitusHR, hazard ratios