BACKGROUND:Intravenous thrombolytic therapy (IVT) is recommended for patients with acute ischemic stroke (AIS) and disabling deficits, regardless of National Institutes of Health Stroke Scale (NIHSS) score. The benefit of IVT in patients with mild AIS was, however, not documented in recent trials. The aim of this study was to evaluate the effectiveness of IVT in mild AIS in a nationwide registry-based study. METHODS:AIS patients from the Norwegian Stroke Registry (2016-2022) with a National Institutes of Health Stroke Scale (NIHSS) score ≤ 5 at admission were included. Using 1:1 propensity score matching, 1736 IVT-treated patients were matched with 1736 controls. Primary outcome was excellent functional outcome (modified Rankin Scale [mRS] score 0-1) at 90 days. Secondary outcomes included mRS 0-2, a favorable mRS shift (range 0-6), and death within 28 and 90 days. Data on symptomatic intracerebral hemorrhage (sICH) were available only for the IVT group. RESULTS:At 90 days, 68.4% of IVT-treated patients and 61.2% of controls achieved mRS 0-1 (OR 1.39; 95% CI 1.20-1.60). IVT was associated with a higher probability of achieving excellent functional outcome in patients with NIHSS 4-5 (OR 1.53; 95% CI 1.06-2.21) and NIHSS 2-3 (OR 1.64; 95% CI 1.32-2.03), but not NIHSS 0-1 (OR 1.14; 95% CI 0.89-1.44). No significant differences in overall mortality were observed. SICH occurred in 3.7% of IVT-treated patients. CONCLUSION:IVT was associated with favorable functional outcomes for mild AIS, but not in patients with NIHSS 0-1.

INTRODUCTION:Whether sex influence the clinical pathway of stroke, has been debated. In this study, we want to compare and add knowledge to presentation of symptoms and time to treatment of cerebral infarction in men and women. PATIENTS AND METHODS:Data on 38,489 patients with cerebral infarction from 2018 to 2022 were obtained from the Norwegian Stroke Registry (NHR). The analyses were stratified by sex and age groups. RESULTS:Overall, there was a substantial sex parity for both focal neurological deficits and time to treatment. However, women were less likely to be awake at admission (RR 0.96, CI 0.95-0.97). A higher proportion of women presented with FAST symptoms (RR 1.06, CI 1.04-1.07), and women presented more often with arm paresis (RR 1.11, CI 1.08-1.14), facial paresis (RR 1.08, CI 1.05-1.11), aphasia (RR 1.17, CI 1.13-1.21), leg paresis (RR 1.18, CI 1.15-1.21) and neglect (RR 1.24, CI 1.18-1.31). Men presented more often with ataxia (RR 0.85, CI 0.81-0.89) and double vision (RR 0.72, CI 0.64-0.81). At admission, women had significantly higher National Institutes of Health Stroke Scale (NIHSS) score compared to men (average 5.60 vs 4.66), and significantly longer time from symptom onset to notification of Emergency Medical Communication Center (EMCC; average 298 vs 282 min). DISCUSSION AND CONCLUSION:Our findings indicate a large degree of sex equality in terms of symptoms and time to treatment for Norwegian patients with cerebral infarction. Further research exploring possible sex disparity in stroke treatment, is warranted.

INTRODUCTION:The risk of death increases significantly after stroke as shown in previous studies from the general stroke population; however, specific knowledge regarding survival after wake-up stroke and unknown-onset stroke is lacking. We aimed to report short- and long-term survival after ischaemic stroke, by mode of onset, using data from a high-quality nationwide stroke registry. PATIENTS AND METHODS:Data from the Norwegian Stroke Registry for the period 2014-2023 were retrieved to assess short- and long-term survival after first-ever ischaemic stroke. Short-term survival was defined as surviving the first 30 days after stroke, and long-term survival was examined in 30-day survivors. Kaplan-Meier survival probabilities were estimated at 30 days, 1, 3 and 5 years after stroke for all patients and stratified by mode of onset: known-onset stroke, wake-up stroke and unknown-onset stroke. The relationship between mode of onset and all-cause mortality was assessed using multivariable regression models. RESULTS:Of the 68,025 patients included, 45,084 had known-onset stroke, 12,429 wake-up stroke and 10,512 unknown-onset stroke. The 30-day survival rate was 91.3% for known-onset stroke, 92.4% for wake-up stroke and 91.7% for unknown-onset stroke, while 5-year survival rate among 30-day survivors was 65.4%, 67.6% and 60.4%, respectively. For 30-day survivors, using known-onset stroke as reference group, the adjusted HR for all-cause mortality in the total observation period for wake-up stroke was 0.99 (95% CI, 0.95-1.04), P = .778 and for unknown-onset stroke the HR was 1.19 (95% CI, 1.14-1.25), P < .001. CONCLUSION:Short-term survival was similar across all modes of onset, while unknown-onset stroke was associated with poorer long-term survival.

Background Rapid diagnosis and treatment of stroke is important for good outcome. In some cases, patients with ischemic stroke arrive at hospital too late for reperfusion therapy. This may be the case especially in rural areas where time spent during transport may delay or even preclude thrombolytic treatment after hospital arrival. We aimed to estimate the extent and clinical relevance of this problem in the Norwegian population. Methods We collected data for all reported acute ischemic strokes for the years 2017 and 2018. Transport times from home to hospital were calculated from geographical data and related to frequency of thrombolysis, thrombectomy and clinical outcome after 3 months. Results The frequency of reperfusion therapy decreased significantly as transport time increased. Six percent (564) of 9 428 patients were classified as having a prolonged time in transport. In this group, frequency of intravenous thrombolysis was 10,5%. as opposed to 28,2% when prolonged transport was not present. Thrombectomy was performed in 2.1% versus 4.9% in the two groups respectively. We did not find a statistically significant difference between the two groups with regard to clinical outcome as judged by the modified Rankin Scale. Conclusion In the years 2017 and 2018 a relatively small group of Norwegian patients with prolonged time in transport was disfavored concerning access to reperfusion therapy for ischemic stroke. In such cases a prehospital solution for diagnostic work up and treatment might improve access to acute stroke treatment.

INTRODUCTION:Acute ischaemic stroke (AIS) treatment has undergone major changes in the last decades with regards to reperfusion treatment with intravenous thrombolysis (IVT) and mechanical thrombectomy (MT). We analysed temporal trends in reperfusion treatment, functional outcomes and mortality among patients with first-ever AIS. PATIENTS AND METHODS:We included 45,686 first-ever AIS patients registered in the Norwegian Stroke Registry from 2014 to 2021. Temporal trends in reperfusion therapy, functional outcome defined by modified Rankin Scale (mRS) score at 90 days and mortality were assessed in age-and sex-adjusted logistic regression models and in analyses stratified by age and reperfusion treatment. RESULTS:Mean age was 73.8 years and 54.5% were men. The use of reperfusion treatment increased over time (IVT only from 15.5% to 18.1%; MT only from 0.4% to 2.8%; IVT + MT combined, from 0.9% to 3.4%). The proportion of patients achieving mRS 0-2 at 90 days increased from 64.2% to 68.1%. The 90-day mortality decreased from 11.7% to 10.5%. Improvement in 90-day functional outcome was most notable in patients receiving IVT, but was also observed in patients not receiving reperfusion treatment. Patients aged ⩾80 years showed improvement in functional outcome and reduced mortality rate, while less noticeable time trends were observed in patients <80 years. DISCUSSION AND CONCLUSION:Reperfusion therapy for first-ever AIS increased significantly over time, concurrent with significant improvements in functional outcome and lower mortality rate. Improvements in outcome were more prominent in the older population. Improved outcome among non-reperfused patients suggest that factors other than reperfusion therapy contribute to these results.

Background Previous clinical trials found improved outcome of thrombolytic treatment in patients with ischemic wake‐up stroke (WUS) selected by advanced imaging techniques. The authors assessed the effectiveness of thrombolytic treatment in patients with WUS in a nationwide stroke registry. Methods and Results Using propensity score matching, the authors assessed the effectiveness and safety of thrombolytic treatment versus no thrombolytic treatment in 726 patients (363 matched pairs) with WUS in the Norwegian Stroke Registry in 2014 to 2019. Thrombolytic treatment in WUS versus known‐onset stroke was compared in 730 patients (365 matched pairs). Functional outcomes were assessed by the modified Rankin Scale (mRS) at 3 months. A significant benefit of thrombolytic treatment in WUS was seen in ordinal analysis (odds ratio [OR], 1.48 [95% CI, 1.15–1.91]; P=0.003) and for mRS 0 to 2 (OR, 1.81 [95% CI, 1.29–2.52]; P=0.001) but not for mRS 0 or 1 (OR, 1.32 [95% CI, 1.00–1.74]; P=0.050). The proportion of patients with mRS 0 or 1 was lower in patients with WUS who underwent thrombolysis versus those with known‐onset stroke (50.4% versus 59.5%; OR, 0.69 [95% CI, 0.52–0.93]; P=0.013), while outcomes were similar between groups for mRS 0 to 2 and ordinal analysis. Symptomatic intracranial hemorrhage after thrombolytic treatment occurred in 4.4% of patients with WUS and 3.9% of patients with known‐onset stroke (OR, 1.14 [95% CI, 0.54–2.41]; P=0.726). Conclusions Thrombolytic treatment in patients with WUS was associated with improved functional outcome compared with patients with no thrombolytic treatment and was not associated with increased rates of symptomatic intracranial hemorrhage compared with known‐onset stroke. The results indicate that thrombolytic treatment is effective and safe in WUS in a real‐life setting.

Objective To assess the short-term risk of acute myocardial infarction (AMI) associated with procedures performed at outpatient specialised hospital clinics. Methods In this case-crossover, population-based study, we identified first-time AMI cases aged ≥40 years via patient registries and linked them to their surgical intervention in Norway (2008–2016) and Sweden (2001–2014), respectively. The number of individuals with AMI who underwent procedures 0–7 days (hazard period) prior to the AMI diagnosis was compared with cases who were exposed 29–36 days (control period) before the AMI. A total of 6176 patients with AMI who underwent a procedure either during the defined hazard or control period contributed to the analyses. ORs with 95% CIs were computed using conditional logistic regression. Results The mean age of the total population was 74.7 years and 64.6% were male. The relative risk was higher following procedures performed under general/regional anaesthesia for gastrointestinal endoscopy (ORsummary, 4.23, 95% CI 1.58 to 11.31), vascular (ORsummary, 3.12, 95% CI 1.10 to 8.90), urological/gynaecological (ORsummary, 2.30, 95% CI 1.50 to 3.53) and orthopaedic (ORsummary,1.78, 95% CI 1.30 to 2.44) procedures, and for ENT (ear, nose and throat) and mouth procedures (ORsummary, 1.53, 95% CI 1.19 to 1.99) performed under local anaesthesia. Conclusion This large population-based register study from two countries suggests that outpatient procedures are generally safe with regard to the postoperative risk of AMI. However, some procedures, such as gastrointestinal endoscopy, vascular procedures and urological/gynaecological procedures may increase the risk of AMI by twofold or threefold within the first 8 days after the procedures. Further studies are warranted to assess whether the effect is modified by cardiovascular medication or other clinical factors.

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.

The following paper is reprinted with permission from Tidsskrift for Den norske legeforening Publisert: 27. januar 2020. Tidsskr Nor Legeforen. DOI: 10.4045/tidsskr.19.0246 Publisert under åpen tilgang CC BY-ND. Lastet ned fra tidsskriftet.no 4. juni 2023.

Data from clinical health registries, such as medical quality registries, are often used as basis for healthcare quality indicators (QI). To aid the interpretation of quality indicators and support decisions, it is important to quantify the uncertainty around the QI summary statistics. In this paper we suggest a novel method for quantifying such uncertainty: the Coverage uncertainty range. The method is based on the size of the population present in the register relative to the total relevant population and does not make any assumptions about the sampling strategy or the value of the summary statistic. Furthermore, using both simulated data and real-life data from a Norwegian medical quality registry, we illustrate why using confidence intervals when presenting healthcare quality indicators may lead to erroneous conclusions.

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 wake-up 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 <5) was more frequent in ischaemic wake-up stroke (5364/8308, 64.6%, 95% CI: 63.5–65.5) than in known-onset (16,417/26,746, 61.4%, 95% CI: 60.8–62.0) and unknown-onset stroke (3242/5853, 55.4%, 95% CI: 54.1–56.7), while baseline characteristics were otherwise similar to known-onset stroke. Unknown-onset stroke patients were more often female, lived alone and had more severe strokes compared to wake-up stroke and known-onset stroke patients. Unknown-onset stroke patients were more often in need of community-based health care on discharge and had a higher in-hospital mortality. 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.

BACKGROUNDPreoperative cardiovascular evaluations are frequently done before ambulatory ophthalmologic procedures. However, whether these procedures can trigger an acute myocardial infarction (AMI) is unknown.OBJECTIVETo assess the short-term risk for AMI associated with ophthalmologic procedures.DESIGNCase-crossover design.SETTINGPopulation-based nationwide study from Norway and Sweden.PARTICIPANTSFirst-time patients with AMI, aged 40 years and older, identified via inpatient registries and linked to outpatient surgical procedures in Norway (2008 to 2014) and Sweden (2001 to 2014), respectively.MEASUREMENTSUsing self-matching, for each participant, exposure to ophthalmologic procedures in the 0 to 7 days before AMI diagnosis (hazard period) was compared with an 8-day period 30 days earlier, that is, days 29 to 36 before AMI (control period) to estimate the relative risk for an AMI the week after an ophthalmologic procedure. The odds ratios (ORs) with 95% CIs were calculated, using conditional logistic regression. Only patients who had a procedure of interest during either the hazard or control period were included.RESULTSFor the 806 patients with AMI included in this study, there was a lower likelihood of AMI in the week after an ophthalmologic procedure than during the control week (OR, 0.83; 95% CI, 0.75 to 0.91). Furthermore, there was no evidence of increased risk for AMI when analyses were stratified by surgery subtype, anesthesia (local or general), duration, invasiveness (low, intermediate, or high), patient's age (<65 years or ≥65 years), or comorbidity (none vs. any).LIMITATIONPotential bias from time-varying confounders between the hazard and the control periods.CONCLUSIONOphthalmologic procedures done in an outpatient setting did not seem to be associated with an increased risk for AMI.PRIMARY FUNDING SOURCECentral Norway Regional Health Authority and the Swedish Research Council.

Purpose: To assess whether acute myocardial infarction (MI) diagnoses in national health registers are sufficiently correct and complete to replace manual collection of endpoint data for a population-based, epidemiological study. Patients and Methods: Using the Tromso Study Cardiovascular Disease Register for 2013-2014 as gold standard, we calculated correctness (defined as positive predictive value (PPV)) and completeness (defined as sensitivity) of MI cases in the Norwegian Myocardial Infarction Register and the Norwegian Patient Register separately and in combi-nation. We calculated the sensitivity and PPV with 95% confidence intervals using the Clopper-Pearson Exact test. Results: We identified 153 MI cases in the gold standard. In the Norwegian Myocardial Infarction Register, we found a PPV of 97.1% (95% confidence interval (CI) 92.8-99.2) and a sensitivity of 88.2% (95% CI 82.0-92.9). In the Norwegian Patient Register, the PPV was 96.3% (95% CI 91.6-98.8) and the sensitivity was 85.6% (95% CI 79.0-90.8). The com-bined dataset of the Norwegian Myocardial Infarction Register and the Norwegian Patient Register had a PPV of 96.6% (95% CI 92.1-98.9) and a sensitivity of 91.5% (95% CI 85.9- 95.4). Conclusion: MI diagnoses in both the Norwegian Myocardial Infarction Register and the Norwegian Patient Register were highly correct and complete, and each of the registers could be considered as endpoint sources for the Tromso Study. A combination of the two national registers seemed, however, to represent the most comprehensive data source overall. The benefits of using data from national registers as endpoints in epidemiological studies include faster, less resource-intensive access to nationwide data and considerably lower loss to follow-up, compared to manual data collection in a limited geographical area.

Background US and European guidelines diverge on whether to vaccinate adults who are not at high risk for cardiovascular events against influenza. Here, we investigated the associations between influenza vaccination and risk for acute myocardial infarction, stroke and pulmonary embolism during the 2009 pandemic in Norway, when vaccination was recommended to all adults. Methods Using national registers, we studied all vaccinated Norwegian individuals who suffered AMI, stroke, or pulmonary embolism from May 1, 2009 through September 30, 2010. We defined higher-risk individuals as those using anti-diabetic, anti-obesity, anti-thrombotic, pulmonary or cardiovascular medications (i.e. individuals to whom vaccination was routinely recommended); all other individuals were regarded as having lower-risk. We estimated incidence rate ratios with 95% CI using conditional Poisson regression in the pre-defined risk periods up to 180 days following vaccination compared to an unexposed time-period, with adjustment for season or daily temperature. Results Overall, we observed lower risk for cardiovascular events following influenza vaccination. When stratified by baseline risk, we observed lower risk across all three outcomes in association with vaccination among higher-risk individuals. In this subgroup, relative risks were 0.72 (0.59–0.88) for AMI, 0.77 (0.59–0.99) for stroke, and 0.73 (0.45–1.19) for pulmonary embolism in the period 1–14 days following vaccination when compared to the background period. These associations remained essentially the same up to 180 days after vaccination. In contrast, the corresponding relative risks among subjects not using medications were 4.19 (2.69–6.52), 1.73 (0.91–3.31) and 2.35 (0.78–7.06). Conclusion In this nationwide study, influenza vaccination was associated with overall cardiovascular benefit. This benefit was concentrated among those at higher cardiovascular risk as defined by medication use. In contrast, our results demonstrate no comparable inverse association with thrombosis-related cardiovascular events following vaccination among those free of cardiovascular medications at baseline. These results may inform the risk–benefit balance for universal influenza vaccination.

BACKGROUND:Treatment of stroke in Norway is decentralised; patients with stroke are treated at 50 different hospitals. We have surveyed the treatment of stroke in these hospitals and collated this with data from the Norwegian Stroke Registry. We wished to investigate whether there was any variation in treatment interventions and treatment outcomes between university hospitals and local hospitals. MATERIAL AND METHOD:A questionnaire survey among all Norwegian hospitals examined treatment interventions and resource availability. Data from the Norwegian Stroke Registry in 2015-2016 (n = 17 183) were used to compare patient characteristics and treatment outcomes for patients in university hospitals (n = 5 312) and local hospitals (n = 11 871). Treatment quality was measured using the quality indicators in the Norwegian Stroke Registry. RESULTS:The median age in the university hospitals was 75 years (interquartile range 65-83), and 44.1% of the patients were women. The median age in the local hospitals was 76 years (interquartile range 67-85); 46.7% women. Goal achievement on five out of ten quality indicators was high; for example, more than 90% of the patients were treated in a stroke unit, irrespective of the type of hospital. At the university hospitals, 1 038 (19.0%) of patients received thrombolytic therapy, compared to 1 612 (17.2%) in the local hospitals. Adjusted for age and level of consciousness, the probability of being self-reliant three months after the stroke was higher in local hospitals (OR 1.15, CI 1.04-1.27). INTERPRETATION:The decentralised stroke treatment in Norway accomplishes high and moderate goal achievement on the Norwegian Stroke Registry's quality indicators. The quality of treatment in local hospitals appears to be equally good or better than that provided in university hospitals.

Percutaneous coronary intervention (PCI) is a plausible triggering factor for stroke, yet the magnitude of this excess risk remains unclear. This study aimed to quantify the transient change in risk of stroke for up to 12 weeks after PCI. We applied the case crossover method, using data from the Norwegian Patient Register on all hospitalizations in Norway in the period of 2008 to 2014. The relative risk (RR) of ischemic stroke was highest during the first 2 days after PCI (RR 17.5, 95% confidence interval [CI] 4.2 to 72.8) and decreased gradually during the following weeks. The corresponding RR was 2.0 (95% CI 1.2 to 3.3) 4 to 8 weeks after PCI. The RR for women was more than twice as high as for men during the first 4 postprocedural weeks, RR 10.5 (95% CI 3.8 to 29.3) and 4.4 (95% CI 2.7 to 7.2), respectively. Our results were compatible with an increased RR of hemorrhagic stroke 4 to 8 weeks after PCI, but the events were few and the estimates were very imprecise, RR 3.0 (95% CI 0.8 to 11.1). The present study offers new knowledge about PCI as a trigger for stroke. Our estimates indicated a substantially increased risk of ischemic stroke during the first 2 days after PCI. The RR then decreased gradually but stayed elevated for 8 weeks. Increased awareness of this vulnerable period after PCI in clinicians and patients could contribute to earlier detection and treatment for patients suffering a postprocedural stroke. (C) 2016 Elsevier Inc. All rights reserved.

Aims: Health registers are essential sources of data used in a wide range of stroke research, including epidemiological, clinical and healthcare studies. Regardless of the type of register, the data must be of high quality to be useful. In this study, we investigated and compared the correctness and completeness of the Norwegian Patient Register (an administrative health register) and the Norwegian Stroke Register (a medical quality register for acute stroke). Methods: We reviewed the medical records for 5192 admissions to hospital in 2012 and defined cases of stroke in the two registers as true positive, false positive, true negative or false negative. We calculated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value with 95% confidence intervals assuming a normal approximation of the binomial distribution. Results: The Norwegian Stroke Register was highly correct and relatively complete (sensitivity 88.1%, specificity 100% and PPV 98.6%). The Norwegian Patient Register was more complete, but less correct, when we included both the main and secondary diagnoses of stroke (sensitivity 96.8%, specificity 99.6% and PPV 79.7%); restricting the analyses to the main diagnoses of stroke resulted in less complete and more correct registrations (sensitivity 86.1%, specificity 99.9% and PPV 93.5%). Conclusions: The Norwegian Stroke Register and the Norwegian Patient Register are adequately complete and correct to serve as valuable sources of data for epidemiological, clinical and healthcare studies, as well as for administrative purposes.

Medical quality registers are useful sources of knowledge about diseases and the health services. However, there are challenges in obtaining valid and reliable data. This study aims to assess the reliability in a national medical quality register.