Data quality of surgery for carotid artery stenosis. Are the national vascular registries reliable?

Objectives. To study completeness of reporting carotid endarterectomies, including peri-operative stroke and mortality rate, in a national vascular registry, NorKfar, and a national administrative registry, The Norwegian Patient Register (NPR). Design. Comparative registry-based national study. Materials. Member hospitals of NorKar, including 89% of carotid endarterectomies in Norway, were compared With relevant data hi NPR for the years 2000-2002. Methods. We compared procedure-codes, diagnosis-codes, in-hospital death and the occurrence of peri-operative stroke after treatment for carotid artery stenosis in the two registries to evaluate completeness. Results. Compared with the NPR numbers, 16% of carotid endarterectomies were missing in the reports from member hospitals of NorKar. Further, during this three-year period, there Was an under-reporting of seven strokes and two deaths. The discrepancy zoos most pronounced in 2001. Conclusions. There is an under-reporting of patients operated on for carotid artery stenosis in NorKar according to NPR numbers as well as an under-reporting of early deaths and strokes. There is a need for better quality data in the NorKar Registry. Registry quality would be likely to improve if patient identifiable data were available in both registries.