The stenotic carotid artery plaque : prevalence, risk factors and relations to clinical disease : the Tromsø study

Stroke is the second leading cause of death in the world and is responsible for a high percentage of major disability, requiring substantial resources spent on care and rehabilitation. Atherosclerosis due to lipid accumulation in the vessel wall with formation of stenotic atheromatous plaques in the carotid bifurcation and/or the internal carotid artery is an important cause of stroke. In 1991, two large, multi-center trials reported that carotid endarterectomy was of benefit to patients with a degree of stenosis above 70%, and thus showed that the degree of stenosis was a major risk factor for ipsilateral stroke. However, it is well known that many high-grade stenoses remain stable and never cause cerebrovascular events, while others develop rapidly and produce serious, potentially life-threatening disease. While the majority of patients presenting with transient ischemic attack (TIA) and stroke has an ipsilateral carotid lesion, only about half of them have a hemodynamically significant carotid stenosis. Only 5-15% of strokes are heralded by a TIA. This has led to a search for additional risk factors which might help identify the individuals with a high risk for stroke

Decompressive hemicraniectomy for space-occupying brain infarction: Nationwide population-based registry study

Objective: We analyzed data from the Norwegian Stroke Registry (NSR) to study access to and outcomes of decompressive hemicraniectomy for brain infarction in a nationwide routine clinical setting. We also discretionary assessed whether the outcomes were comparable with those achieved in randomized controlled trials (RCTs), and whether the use was in accordance with guidelines. Methods: The NSR is a nationwide (population 5.3 million) clinical quality registry. We included all stroke-cases operated in 2017 through 2019, and retrieved data on baseline characteristics, treatment and functional outcome after three months (dichotomized modified Rankin Scale score; favorable (0-3) or unfavorable (4-6)). Crude treatment rates and the expected proportion of patients transferred from a local hospital to a stroke-center for the operation were estimated, based on the total population’s distribution of residency. Results: The 68 cases were 17 (25%) women and 51 (75%) men with a median National Institute of Health Stroke Scale (NIHSS) score on admission of 14.0 (inter-quartile range (IQR) 11.0) and a median time from onset to hemicraniectomy of 34.3 (IQR 40.9) hours. The crude treatment rate varied between regions from 0.29 to 1.40 operations per 100,000 population per year, and the proportion transferred from a local hospital (50%) was lower than expected (68%). A favorable outcome was achieved in 20/52 (38.5%) cases. Conclusions: The findings indicate gender- and geographic-inequalities in access. Among operated cases, outcomes were comparable with those reported from RCTs, and the use in accordance with recommendations in the current guidelines from the American Stroke Association

Impact of chronic inflammation, assessed by hs-CRP, on the association between red cell distribution width and arterial cardiovascular disease: the Tromso Study

Red cell distribution width (RDW), a measure of variability in size of circulating erythrocytes, is associated with arterial cardiovascular disease (CVD), but the underlying mechanism remains unclear. We aimed to investigate the impact of chronic inflammation as measured by high-sensitivity C-reactive protein (hs-CRP) on this relationship, and explore whether RDW could be a mediator in the causal pathway between inflammation and arterial CVD. Baseline characteristics, including RDW and hs-CRP, were obtained from 5,765 individuals attending a population-based cohort study. We followed up participants from inclusion in the fourth survey of the Tromsø Study (1994/1995) until December 31, 2012. Multivariable Cox-regression models were used to calculate hazard ratios (HR) with 95% confidence intervals (CI) for incident myocardial infarction (MI) and ischemic stroke across quintiles of hs-CRP and RDW. Subjects with hs-CRP in the highest quintile had 44% higher risk of MI (HR: 1.44, 95% CI: 1.14–1.80), and 64% higher risk of ischemic stroke (HR: 1.64, 95% CI: 1.20–2.24) compared with subjects in the lowest quintile. RDW mediated 7.2% (95% CI: 4.0–30.8%) of the association between hs-CRP and ischemic stroke. Subjects with RDW in the highest quintile had 22% higher risk of MI (HR: 1.22, 95% CI: 0.98–1.54) and 44% higher risk of ischemic stroke (HR: 1.44, 95% CI: 1.06–1.97) compared with subjects in the lowest quintile. These risk estimates were slightly attenuated after adjustments for hs-CRP. Our findings suggest that chronic inflammation is not a primary mechanism underlying the relationship between RDW and arterial CVD

Trends in prevalence of ultrasound-assessed carotid atherosclerosis in a general population over time. The Tromsø Study 1994-2016

Background: During the past decades, there has been a shift in risk factor levels in many high-income countries, with decrease in smoking, blood pressure and cholesterol levels, while body mass index, obesity and diabetes increase. The diverging trends may have opposite effects on prevalence of atherosclerosis. We aimed to assess carotid plaque prevalence and the association with risk factor levels in a general population over a period of 22 years. Methods: Prevalence of plaque, number of plaques and total plaque area in the carotid arteries were assessed in three repeated cross-sectional surveys of the population-based Tromsø Study from 1994 through 2016. The number of participants from the first to the last survey was 6362, 7069 and 3021. All surveys included physical examinations, questionnaires, and blood samples. Multivariable logistic regression analysis models were fitted to assess the relationship between risk factors and carotid plaque. Results: We found no significant change in plaque burden over a period of 22 years, neither when measured as plaque presence, plaque number or total plaque area. Plaques were more frequent in men (70%) than in women (59.4%) and increased by age. Systolic blood pressure and smoking increased, while BMI and diabetes decreased over time both in participants with and without plaque. Most risk factors remained higher in participants with plaque than in plaque- free participants while cholesterol levels decreased and reached similar levels in both groups. Age, male sex, systolic blood pressure, smoking, diabetes and HDL cholesterol (inverse) were associated with plaque prevalence. Conclusions: Plaque prevalence remained stable in the observation period. Favorable reductions in systolic blood pressure, cholesterol and smoking may have been partly counteracted by increased diabetes prevalence. Risk factor levels remained higher in participants with plaque than in plaque-free participants, indicating a potential for further improvement in primary prevention of carotid atherosclerosis

Serum osteoprotegerin levels are related to height loss: The Tromsø Study

Severe loss of body height is often a consequence of osteoporotic vertebral fractures. Osteoprotegerin (OPG) and receptor activator of nuclear factor-kB ligand (RANKL) are cytokines essential for the regulation of bone resorption. The aim of this study was to assess the relationship between the OPG/RANKL system and height loss. A total of 4,435 inhabitants from the municipality of Tromsø, Norway (2,169 men and 2,266 women) were followed for 6 years. Baseline measurements included height, weight, bone mineral density, OPG, RANKL, serum parathyroid hormone and information about lifestyle, prevalent diseases and use of medication. Height was measured again at follow-up, and the loss of height was categorized into 4 groups: ≤1, 1.1–2, 2.1–3, >3 cm. We found increasing height loss with increasing baseline OPG levels in both men and women (P trend = 0.02 and 0.001, respectively), after adjustments for age and other confounders. However, when the women were stratified according to menopausal status and use of hormone replacement therapy (HRT), a significant relationship was present only among postmenopausal women not using HRT (P trend = 0.02). No relations between OPG and height loss were found in post-menopausal HRT-users and premenopausal women (P trend ≥0.39). We conclude that height loss is positively associated with OPG in men and in postmenopausal women not using HRT. No relationship was found between RANKL and height loss

Prevalence of intracranial artery stenosis in a general population using 3D-time of flight magnetic resonance angiography

Background: Data on prevalence of intracranial artery stenosis (ICAS) in Western populations is sparse. The aim of the study was to assess the prevalence and risk factors for ICAS in a mainly Caucasian general population. Methods: We assessed the prevalence of ICAS in 1847 men and women aged 40 to 84 years who participated in a cross-sectional population-based study, using 3-dimensional time-of-flight 3 Tesla magnetic resonance angiography. ICAS was defined as a focal luminal flow diameter reduction of ≥50 %. The association between cardiovascular risk factor levels and ICAS was assessed by multivariable regression analysis. Results: The overall prevalence of ICAS was 6.0 % (95 % confidence interval (CI) 5.0–7.2), 4.3 % (95 % CI 3.1–5.7) in women and 8.0 % (95 % CI 6.3–10.0) in men. The prevalence increased by age from 0.8 % in 40-54 years age group to 15.2 % in the 75-84 years age group. The majority of stenoses was located to the internal carotid artery (52.2 %), followed by the posterior circulation (33.1 %), the middle cerebral artery (10.8 %) and the anterior cerebral artery (3.8 %). The risk of ICAS was independently associated with higher age, male sex, hypertension, hyperlipidemia, diabetes mellitus, current smoking and higher BMI. Conclusions: The prevalence of ICAS in a general population of Caucasians was relatively high and similar to the prevalence of extracranial internal carotid artery stenosis in previous population-based studies

Data from national health registers as endpoints for the Tromsø Study: Correctness and completeness of stroke diagnoses

Aim: To assess whether stroke diagnoses in national health registers are sufficiently correct and complete to replace manual collection of endpoint data for the Tromsø Study, a population-based epidemiological study. Method: Using the Tromsø Study Cardiovascular Disease Register for 2013–2014 as the gold standard, we calculated correctness (defined as positive predictive value, PPV) and completeness (defined as sensitivity) of stroke cases in four different data subsets derived from the Norwegian Patient Register and the Norwegian Stroke Register. We calculated the sensitivity and PPV with 95% confidence intervals (CIs) assuming a normal approximation of the binomial distribution. Results: In the Norwegian Stroke Register we found a sensitivity of 79.8% (95% CI 74.2–85.4) and a PPV of 97.5% (95% CI 95.1–99.9). In the Norwegian Patient Register the sensitivity was 86.4% (95% CI 81.6–91.1) and the PPV was 84.2% (95% CI 79.2–89.2). The overall highest levels were found in a subset based on a linkage between the Norwegian Stroke Register and the Norwegian Patient Register, with a sensitivity of 88.9% (95% CI 84.5–93.3), and a PPV of 89.3% (95% CI 85.0–93.6). Conclusions: Data from the Norwegian Patient Register and from the linked data set between the Norwegian Patient Register and the Norwegian Stroke Register had acceptable levels of correctness and completeness to be considered as endpoint sources for the Tromsø Study Cardiovascular Disease Register. The benefits of using data from national registers as endpoints in epidemiological studies must be weighed against the impact of potentially decreased data quality

Wake-up stroke and unknown-onset stroke; occurrence and characteristics from the nationwide Norwegian Stroke Register

Introduction: Population-based knowledge of the characteristics of wake-up stroke and unknown-onset stroke is limited. We compared occurrence and characteristics of ischaemic and haemorrhagic wake-up stroke, unknown-onset stroke and known-onset stroke in a nationwide register-based study. Patients and methods: We included patients registered in the Norwegian Stroke Register from 2012 through 2019. Age, sex, risk factors, clinical characteristics, acute stroke treatment and discharge destination were compared according to stroke type and time of onset. Results: Of the 60,320 patients included, 11,451 (19%) had wake-up stroke, 11,098 (18.4%) had unknown time of onset and 37,771 (62.6%) had known symptom onset. The proportion of haemorrhagic stroke was lower among wakeup stroke patients (1107/11,451, 9.7%, 95% CI: 9.1–10.2) than for known-onset stroke (5230/37,771, 13.8%, 95% CI: 13.5–14.2) and for unknown-onset stroke (1850/11,098, 16.7%, 95% CI: 16.0–17.4). Mild stroke (NIHSS Discussion and conclusions: Ischaemic wake-up strokes shared baseline characteristics with known-onset strokes, but tended to be milder. Ischaemic unknown-onset stroke patients differed significantly from wake-up stroke, emphasising the importance of considering them as separate entities

Pain tolerance after stroke: The Tromsø study

Background: Stroke lesions might alter pain processing and modulation by affecting the widely distributed network of brain regions involved. We aimed to compare pain tolerance in stroke survivors and stroke-free persons in the general population, with and without chronic pain. Methods: We included all participants of the sixth and seventh wave of the population-based Tromsø Study who had been tested with the cold pressor test (hand in cold water bath, 3°C, maximum time 106 s in the sixth wave and 120 s in the seventh) and who had information on previous stroke status and covariates. Data on stroke status were obtained from the Tromsø Study Cardiovascular Disease Register and the Norwegian Stroke Register. Cox regression models were fitted using stroke prior to study attendance as the independent variable, cold pressor endurance time as time variable and hand withdrawal from cold water as event. Statistical adjustments were made for age, sex, diabetes, hypertension, hyperlipidaemia, body mass index and smoking. Results: In total 21,837 participants were included, 311 of them with previous stroke. Stroke was associated with decreased cold pain tolerance time, with 28% increased hazard of hand withdrawal (hazard ratio [HR] 1.28, 95% CI 1.10–1.50). The effect was similar in participants with (HR 1.28, 95% CI 0.99–1.66) and without chronic pain (HR 1.29, 95% CI 1.04–1.59). Conclusions: Stroke survivors, with and without chronic pain, had lower cold pressor pain tolerance, with possible clinical implications for pain in this group. Significance: We found lower pain tolerance in participants with previous stroke compared to stroke-free participants of a large, population-based study. The association was present both in those with and without chronic pain. The results may warrant increased awareness by health professionals towards pain experienced by stroke patients in response to injuries, diseases and procedures

Prevalence of unruptured intracranial aneurysms: impact of different definitions-the Tromsø Study

Background - Management of incidental unruptured intracranial aneurysms (UIAs) remains challenging and depends on their risk of rupture, estimated from the assumed prevalence of aneurysms and the incidence of aneurysmal subarachnoid haemorrhage. Reported prevalence varies, and consistent criteria for definition of UIAs are lacking. We aimed to study the prevalence of UIAs in a general population according to different definitions of aneurysm. Methods - Cross-sectional population-based study using 3-dimensional time-of-flight 3 Tesla MR angiography to identify size, type and location of UIAs in 1862 adults aged 40–84 years. Size was measured as the maximal distance between any two points in the aneurysm sac. Prevalence was estimated for different diameter cutoffs (≥1, 2 and 3 mm) with and without inclusion of extradural aneurysms. Results - The overall prevalence of intradural saccular aneurysms ≥2 mm was 6.6% (95% CI 5.4% to 7.6%), 7.5% (95% CI 5.9% to 9.2%) in women and 5.5% (95% CI 4.1% to 7.2%) in men. Depending on the definition of an aneurysm, the overall prevalence ranged from 3.8% (95% CI 3.0% to 4.8%) for intradural aneurysms ≥3 mm to 8.3% (95% CI 7.1% to 9.7%) when both intradural and extradural aneurysms ≥1 mm were included. Conclusion - Prevalence in this study was higher than previously observed in other Western populations and was substantially influenced by definitions according to size and extradural or intradural location. The high prevalence of UIAs sized <5 mm may suggest lower rupture risk than previously estimated. Consensus on more robust and consistent radiological definitions of UIAs is warranted