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

OBJECTIVES: Life-style factors have been associated with the risk for aneurysmal subarachnoid hemorrhage (aSAH), but it is not clear whether body mass index (BMI) and serum lipids are associated with risk. We prospectively assessed these associations in two large population studies. METHODS: A total of 65,526 participants in the Nord-Trøndelag Health Study (1995-1997) and 26,882 participants in the Tromsø Study (1994-1995) were included. Studies included measurements of body weight and height, serum lipids, and self-administered questionnaires. Participants who experienced aSAH were identified, and hazard ratios (HRs) were estimated using Cox regression analysis. RESULTS: During 11 years of follow-up, aSAH was diagnosed in 122 participants. Overweight (BMI 25-29.9) was negatively associated with the risk of aSAH (HR 0.7, 95% CI 0.4-1.0). There was no over all association of total serum cholesterol, HDL cholesterol, or triglycerides with the risk of aSAH, but in participants younger than 50 years, HDL cholesterol was inversely associated with the risk (HR per standard deviation increase 0.6, 95% CI 0.4-0.9). CONCLUSIONS: Overweight may be associated with reduced risk of aSAH, but there was no over all association of total serum cholesterol, HDL cholesterol, or triglycerides with the risk of aSAH in this prospective study.

Incidence of aneurysmal subarachnoid hemorrhage in Norway, 1999-2007.

OBJECTIVE: To investigate changes and regional variations in annual incidence rates of aneurysmal subarachnoid hemorrhage (SAH) in Norway between 1999 and 2007. METHODS: The authors retrospectively reviewed data from the Norwegian Patient Register for the period 1999-2007. RESULTS: Crude incidence of aneurysmal SAH was 10.0/100,000 person years [95% CI (confidence interval): 9.7-10.3] and was higher in women (12.0/100,000 person years; 95% CI: 11.5-12.5) than men (8.1/100,000 person years; 95% CI: 7.7-8.4). Decreasing annual incidence rates were observed from 11.1/100,000 person years (95% CI: 10.5-11.6) in the period 1999-2001 to 8.9/100,000 person years (95% CI: 8.4-9.4) in the period 2005-2007 (P for trend <0.001). Regional variations were observed, from 8.4/100,000 person years (95% CI: 7.7-9.00) in the southern region, 10.4/100,000 person years (95% CI: 9.5-11.2) in the central region and 11.9/100,000 person years (95% CI: 10.8-12.9) in the northern region. CONCLUSIONS: Incidence of aneurysmal SAH in Norway decreased from 1999 to 2007, with significant regional variations indicating an increasing gradient from south to north.

Introduction of endovascular embolization for intracranial aneurysms in a low-volume institution.

BACKGROUND: Studies indicate a relationship between hospital caseload and health outcomes after both surgical and endovascular repair of intracranial aneurysms. PURPOSE: To evaluate outcomes after introduction of endovascular embolization for intracranial aneurysms in a low-volume regional university hospital. MATERIAL AND METHODS: Retrospective study of 243 consecutive patients treated for 284 intracranial aneurysms with endovascular embolization or surgical clipping from 2000 to 2006 at the University Hospital of North Norway. Postoperative complications were registered. The Glasgow Outcome Scale (GOS) was used for assessment of outcome. RESULTS: The mean annual number of procedures was 39 (microsurgery 23, embolization 16). Seventy-four percent of patients with ruptured aneurysms and all patients with unruptured aneurysms had a favorable outcome (GOS 4 or 5) at 1 year follow-up. Patients with subarachnoid hemorrhage were more likely to experience postoperative complications than patients treated for unruptured aneurysms (42% versus 8% of the patients, P<0.01). The immediate incomplete occlusion rate (Raymond II-III) in the initial embolization procedure was 29%. Ten endovascularly treated patients and one surgically treated patient required retreatments due to residual aneurysm or neck remnants. CONCLUSION: The present study indicates that acceptable outcome from aneurysm treatment, both endovascular and microsurgical, is possible in a low-volume institution.

Cognitive function, drusen, and age-related macular degeneration: a cross-sectional study.

PURPOSE: To examine the cross-sectional relationship between drusen, late age-related macular degeneration (AMD), and cognitive function. METHODS; We included 2149 stroke-free participants from the population-based Tromsø Study in Norway. Retinal photographs were graded for presence of drusen and AMD. Cognitive function was assessed using the verbal memory test (short verbal memory), digit-symbol coding test (processing speed), and the tapping test (psychomotor tempo). We assessed the relationship between drusen, late AMD, and cognitive test scores, adjusted for potential confounders. RESULTS: Late AMD was associated with decreased performance in the verbal memory test (standardized ß=-0.23, 95% confidence interval (CI): -0.51 to -0.01). Intermediate and large drusen were associated with decreased performance in the digit-symbol coding test (standardized ß=-0.14 and -0.19, 95% CIs: -0.23 to -0.05 and -0.29 to -0.09, respectively). Participants with large drusen were more likely to have test scores in the lowest quartile of the digit-symbol coding test (odds ratio (OR)=1.9, 95% CI: 1.1-3.5) and the tapping test (OR=1.6, 95% CI: 1.0-2.6), but not in the verbal memory test (OR=1.0, 95% CI: 0.6-1.6). CONCLUSIONS: The findings suggest a relationship between drusen deposition and reduced cognitive function. Although the relationships between drusen, late AMD, and the cognitive test results varied in strength and significance across the types of cognitive test, and may partly have been caused by residual confounding, it is not unlikely that a genuine but weaker relationship exists between drusen deposition and cognitive decline.

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.

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.