Aim The Swedish National Patient Register offers unique opportunities for epidemiological research of paediatric ischaemic stroke. We aimed to validate the diagnosis of paediatric ischaemic stroke in the National Patient Register to ensure the quality of future research. Methods The PedStroke cohort consists of 1606 individuals aged <18 years with a diagnosis of paediatric ischaemic stroke (ICD‐10: I63, I64; ICD‐8 and 9: 433, 434, 436) in Swedish national health registers between 1969 and 2016. We selected 292 cases for validation by reviewing medical charts. Results In all, 277 of the 292 medical charts were received, of which 273 had enough information to qualify for review. The diagnosis was correct in 242/273 cases, yielding a positive predictive value (PPV) of 89% (95% confidence interval (CI): 0.85–0.92) for paediatric ischaemic stroke in the National Patient Register. After validation, seven cases of 222 with childhood stroke were re‐categorised to perinatal stroke, resulting in a total of 56 perinatal stroke cases. In the Medical Birth Register, 38 stroke cases were identified of which 37 had correct diagnosis, generating a PPV of 97% (95% CI: 0.92–1.0). Incorrect diagnoses decreased over time and the number of diagnoses confirmed by radiology increased correspondingly. Conclusion The National Patient Register is reliable for epidemiological research of paediatric ischaemic stroke because of its high PPV for this diagnosis.

Background and Purpose: Ischemic stroke is a common cause of death in adults, however, mortality after pediatric ischemic stroke is not well explored. We investigate long-term and cause-specific mortality in children with ischemic stroke and their first-degree relatives. Methods: Through nationwide Swedish registers, we identified 1606 individuals <18 years old with ischemic stroke between 1969 and 2016 and their first-degree relatives (n=5714). Each individual with ischemic stroke was compared with 10 reference individuals (controls) matched for age, sex, and county of residence. Our main analysis examined 1327 children with ischemic stroke still alive 1 week after the event. First-degree relatives to children with ischemic stroke were compared with first-degree relatives to the reference individuals. Using a Cox proportional hazard regression model, the risk of overall and cause-specific mortality was computed in individuals with pediatric ischemic stroke and their first-degree relatives. Results: The mortality rate in the first 6 months was 40.1 (95% CI, 24.7–55.6) per 1000 person-years compared with 1.1/1000 in controls (95% CI, 0.3–1.9). The overall mortality risk was hazard ratio (HR)=10.8 (95% CI, 8.1–14.3) and remained elevated beyond 20 years (HR=3.9 [95% CI, 2.1–7.1]). Children with ischemic stroke were at increased risk of death from neurological diseases (HR=29.9 [95% CI, 12.7–70.3]), cardiovascular diseases (HR=6.2 [95% CI, 1.8–22.2]), cancers (HR=6.5 [95% CI, 2.6–15.9]) and endocrine, nutritional and metabolic diseases (HR=49.2 [95% CI, 5.7–420.8]). First-degree relatives to children with ischemic stroke had an increased mortality risk (HR=1.21 [95% CI, 1.05–1.39]), with the highest risk among siblings (HR=1.52 [95% CI, 1.09–2.11]) and relatives to individuals with ischemic stroke >28 days of age (HR=1.23 [95% CI, 1.06–1.42]) compared with the relatives of the controls. Conclusions: Long-term mortality increased after pediatric ischemic stroke, even 20 years later, with neurological diseases as the most frequent cause of death.

Background Various frequencies of adverse motor outcomes (cerebral palsy and hemiplegia) after paediatric ischaemic stroke have been reported. Few reports on the risks of adverse motor outcomes in nationwide cohorts and contributing risk factors are available. Objectives To assess risk of adverse motor outcome and potential risk factors thereof after paediatric ischaemic stroke in a nationwide cohort. Methods This nationwide matched cohort study identified 877 children <18 years of age diagnosed with ischaemic stroke through the Swedish national health registers from 1997 to 2016. These children, exposed to ischaemic stroke, alive 1 week after stroke, were matched for age, sex and county of residence with 10 unexposed children. Using Cox regression, we estimated the risk of adverse motor outcomes in children with stroke compared to that in unexposed children. Logistic regression was applied to compare the characteristics of children with and without adverse motor outcomes after stroke. Results Out of the 877 children with ischaemic stroke, 280 (31.9%) suffered adverse motor outcomes compared with 21 (0.2%) of the 8770 unexposed: adjusted hazard ratio (aHR) 167.78 (95% confidence interval (CI) 107.58, 261.66). There were no differences between risk estimates of adverse motor outcome according to age at stroke: perinatal stroke (aHR 124.11, 95% CI 30.45, 505.84) and childhood stroke (aHR 182.37, 95% CI 113.65, 292.64). An association between adverse motor outcome and childhood stroke aOR 1.56 (95% CI 1.05, 2.31) was found when analysing only children with ischaemic stroke. No associations were found between adverse motor outcome and sex, gestational age or parental age at birth. Conclusions The risk of adverse motor outcome is substantial after paediatric ischaemic stroke, especially childhood stroke, confirming results of previous smaller studies. This study found no associations between sex, gestational age or parental age and adverse motor outcome after paediatric ischaemic stroke.

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