Comparison of the validity of stroke diagnoses in a medical quality register and an administrative health register

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.