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.

BackgroundMedical 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.MethodsWe randomly selected 111 patients having had a stroke in 2012. An experienced stroke nurse completed the Norwegian Stroke Register paper forms for all 111 patients by review of the medical records. We then extracted all registered data on the same patients from the Norwegian Stroke Register and calculated Cohen’s kappa and Gwet’s AC1 with 95 % confidence intervals for 51 nominal variables and Cohen’s quadratic weighted kappa and Gwet’s AC2 for three ordinal variables. For two time variables, we calculated the Intraclass Correlation Coefficient.ResultsSubstantial to excellent reliability (kappa > 0.60/AC1 > 0.80) was observed for most variables related to past medical history, functional status, stroke subtype and discharge destination. Although excellent reliability was observed for time of stroke onset (ICC 0.93), this variable was hampered with a substantial amount of missing values. Some variables related to treatment and examinations in hospital displayed low levels of agreement. This applies to heart rate monitoring (kappa 0.17/AC1 0.46), swallowing test performed (kappa 0.19/AC1 0.27) and mobilized out of bed within 24 h after admission (kappa 0.04/AC1 −0.11).ConclusionA majority of the variables in The Norwegian Stroke Register have substantial to excellent reliability. The problem areas seem to be the lack of completeness in the time variable indicating stroke onset and poor reliability in some variables concerning examinations and treatment received in hospital.Electronic supplementary materialThe online version of this article (doi:10.1186/s13104-015-1556-3) contains supplementary material, which is available to authorized users.

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.

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