Marie Søfteland Sandvei

Risk factors for aneurysmal subarachnoid hemorrhage in a prospective population study: the HUNT study in Norway.

Background and Purpose— The morbidity and mortality of subarachnoid hemorrhage (SAH) are high, and established risk factors are scarce. We prospectively assessed the association of blood pressure, smoking, and body mass with the risk of aneurysmal SAH. Methods— All residents ≥20 years were invited to the Nord-Trøndelag Health (HUNT) Study (1984 to 1986) and 74 977 (88.1%) attended. The study included standardized measurements of blood pressure, body weight and height, and self-administered questionnaires. Participants who later had aneurysmal SAH (n=132) were identified, and hazard ratios (HRs), adjusted for age and sex, were estimated using Cox regression analysis. Results— The crude annual incidence of aneurysmal SAH was 9.9 per 100 000 people; the incidence was almost twice as high in women as in men (12.9 versus 6.8, P=0.001). Systolic blood pressure was positively associated with risk (P for trend=0.001). Compared with the reference (<130 mm Hg), the adjusted HR in people with systolic blood pressure of 130 to 139 mm Hg was 2.3 (95% CI, 1.4 to 3.8) and for systolic blood pressure >170 mm Hg, the HR was 3.3 (95% CI, 1.7 to 6.3). Diastolic pressure showed similar positive associations. Compared with never smokers, former (HR, 2.7; 95% CI, 1.4 to 5.1) and current (HR, 6.1; 95% CI, 3.6 to 10.4) smokers had substantially higher risk. Compared with normal weight (body mass index, 18.5 to 24.9 kg/m2), overweight people were at lower risk (HR, 0.6; 95% CI, 0.4 to 1.0). Conclusions— Systolic and diastolic blood pressure were strong predictors of aneurysmal SAH, and there was a substantially increased risk associated with smoking. However, high body mass was associated with reduced risk of aneurysmal SAH.

Incidence and mortality of aneurysmal subarachnoid hemorrhage in two Norwegian cohorts, 1984–2007

Objective: The incidence of aneurysmal subarachnoid hemorrhage (aSAH) ranges from 4 to 10 per 100,000 person-years in most countries, and 30-day case fatality is high. The aim of this study was to estimate the incidence and case fatality of aSAH and to assess preictal predictors of survival in 2 large Norwegian population-based cohort studies. Methods: A total of 94,976 adults (≥20 years) in the Nord-Trøndelag Health Study and 31,753 participants (aged ≥20 years) in the Tromsø Study were included. During follow-up, aSAHs were identified, incidence rates were estimated, and predictors of survival were assessed using Cox and Poisson regression analysis. Results: A total of 214 patients with aSAH were identified during 2,077,927 person-years of follow-up from 1984 to 2007. The incidence rate was 10.3 per 100,000 person-years: 13.3 for women and 7.1 for men. The incidence increased by 2% (95% confidence interval [CI] 0–4) per 5-year time period. Case fatality at 3, 7, and 30 days was 20%, 24%, and 36%. Thirty-day case fatality remained stable during follow-up (odds ratio 1.01, 95% CI 0.97–1.06 per year). Never smokers had poorer survival after aSAH than current and former smokers combined (hazard ratio 1.6, 95% CI 0.9–2.9). Conclusions: The slight increase in incidence of aSAH over time may be explained by differences in diagnostic procedures. Case fatality remained stable during 23 years of follow-up.

Sex differences in risk factors for aneurysmal subarachnoid hemorrhage: a cohort study.

Objective: The purpose of this study was to investigate sex differences in the major established risk factors for aneurysmal subarachnoid hemorrhage (aSAH) in a large, population-based cohort. Methods: Sex differences in the established risk factors for aSAH (smoking, hypertension, and alcohol consumption) were examined in a prospective, population-based cohort consisting of 92,462 participants of the Nord-Trøndelag and the Tromsø Health Studies in Norway. Results: We identified 120 cases of aSAH during 1,002,148 person-years at risk. Compared with the risk in nonsmokers, the risk of aSAH was higher in current cigarette-smoking women than in men (hazard ratio = 8.9, 95% confidence interval [CI] 4.7–17.0 vs hazard ratio = 2.8, 95% CI 1.3–6.1, after adjustment for age and alcohol consumption). The interaction between sex and current smoking was present on an additive scale (relative excess risk due to interaction 3.1, 95% CI 0.5–5.8), indicating a higher risk of aSAH associated with current cigarette smoking in women than in men. No sex differences in the risk of aSAH were observed with respect to hypertension or alcohol consumption. Conclusions: This prospective, population-based cohort study showed that compared with the risk in nonsmokers, the risk of aSAH was higher in current cigarette-smoking women than in men. This finding may at least partially explain the gender gap in aSAH incidence. A more intensive smoking cessation intervention should be considered in women at risk of aSAH.

Joint Effect of Modifiable Risk Factors on the Risk of Aneurysmal Subarachnoid Hemorrhage: A Cohort Study

Background and Purpose— The joint effect of risk factors on the risk of aneurysmal SAH (aSAH) has been studied sparsely. Methods— We examined the potential synergism between cigarette smoking, hypertension, and regular alcohol consumption and the risk of aSAH in a prospective, population-based cohort of participants from the Nord-Trøndelag Health Study and the Tromsø Study in Norway. Interaction was assessed on additive and multiplicative scales. Results— We identified 122 cases of aSAH over 977 895 person-years of follow-up. Interaction was observed between current smoking and hypertension on the additive scale, (relative excess risk because of interaction, 6.40; 95% CI, 0.88–11.92, adjusted for sex and age). We found no significant interaction between hypertension and regular alcohol consumption or current cigarette smoking and regular alcohol consumption on the additive scale. No significant interaction was detected on the multiplicative scale. Conclusions— The joint effect of current smoking and hypertension on the risk of aSAH was stronger than was the sum of the independent effects of each factor. Persons at risk of aSAH should be advised of a markedly stronger risk for aSAH with the combination of current smoking and hypertension. In addition, the finding suggests that combining smoking cessation and blood pressure lowering may have an extra risk reduction effect on preventing aSAH.

Unruptured intracranial aneurysms in the Norwegian Nord-Trøndelag Health Study (HUNT): risk of rupture calculated from data in a population-based cohort study.

BACKGROUND Rupture risk of unruptured intracranial aneurysms (UIAs) has been investigated in studies observing the natural history of this condition. Such studies have been prone to selection bias that may influence the results. OBJECTIVE To calculate the overall rupture risk from data on the prevalence of UIA, which constitutes the population at risk, and the incidence of aneurysmal subarachnoid hemorrhage (aSAH) in the same population. METHODS Data were collected from the Norwegian Nord-Trøndelag Health Study (HUNT), a large population-based cohort study. The prevalence of UIAs was estimated by performing magnetic resonance angiography in 1006 randomly selected volunteers 50 to 65 years of age from this population cohort. The incidence of aSAH was investigated by searching national and hospital registers with thorough case ascertainment to avoid inclusion of nonaneurysmal subarachnoid hemorrhage. RESULTS The prevalence of UIAs was 1.9% and incidence of aSAH was 16.4 per 100,000 person-years. Based on these figures, the overall rupture risk in the 50- to 65-year age group in the HUNT population is 0.87% per year. CONCLUSION This is the first study to estimate rupture risk of intracranial aneurysms from epidemiologic data in a large population-based cohort. This study design is less prone to selection bias and may provide an important supplement to the existing literature of studies of natural history of UIAs.

Risk factors for aneurysmal subarachnoid hemorrhage – BMI and serum lipids: 11‐year follow‐up of the HUNT and the Tromsø Study in Norway

Sandvei MS, Lindekleiv H, Romundstad PR, Müller TB, Vatten LJ, Ingebrigtsen T, Njølstad I, Mathiesen EB, Vik A. Risk factors for aneurysmal subarachnoid hemorrhage – BMI and serum lipids: 11‐year follow‐up of the HUNT and the Tromsø Study in Norway. 
Acta Neurol Scand: 2012: 125: 382–388. 
© 2011 John Wiley & Sons A/S.

Left ventricular myocardial function during the acute phase of a subarachnoid haemorrhage

Objectives. Previous reports suggest that left myocardial ventricular function changes during the course of a subarachnoid haemorrhage. The aim of this study was to evaluate left myocardial ventricular function with tissue Doppler echocardiography at two time points during the acute phase of a subarachnoid haemorrhage. Design. Eighteen consecutive patients (median 52 years, range 33–74) with spontaneous subarachnoid haemorrhage and no history of heart disease were examined at 1–5 days and at 6–11 days following ictus. Eighteen control subjects were included for comparison (52 years, 32–72). Results. Tissue Doppler indices of left ventricular contractility were higher in patients than in controls at both examinations (p<0.001). Indices of left ventricular stroke volume were elevated compared to controls at examination 1 (p<0.05), but not at examination 2. Early diastolic relaxation rate decreased from examination 1 to 2 (p=0.001). Three patients had increased troponin T (range 0.010–0.131µg/l). Conclusion. In patients with subarachnoid haemorrhage, systolic and diastolic function is increased compared to healthy controls, suggesting a hyperdynamic and hypervolemic circulation.

Subarachnoid hemorrhage Another reason not to smoke

Subarachnoid hemorrhage (SAH) has high morbidity and mortality1 and represents a serious and substantial personal and public health burden. Therefore, we need studies of incidence, mortality, and risk factors to understand the disease and enable primary preventive measures.