Purpose: Register-based clinical research is important. However, it is essential that the collected data are reliable for the registers to be a valuable source of information. This study evaluated the quality of humeral fracture data in the Swedish Fracture Register (SFR) and in the Swedish National Patient Register (NPR). Furthermore, a model for improved case ascertainment was developed for future validation processes.
Materials and Methods: Data were obtained from the NPR and SFR for all individuals aged ≥ 16 years with an acute humeral fracture ICD-code treated at Sahlgrenska University Hospital. The true number of humeral fractures (“gold standard”) was determined by cross-linkage between the two registers and a medical charts review. The completeness of registrations in each register was measured as the proportion of registrations compared with the gold standard, and accuracy was measured as positive predictive values (PPV).
Results: The NPR demonstrated a high level of completeness (97%) and lower accuracy (PPV 70%) for acute humeral fractures, whereas the SFR had slightly lower completeness (88%) but perfect accuracy (PPV 100%). The most common systematic error was the registration of re-admissions as acute fractures in the NPR (84% of all erroneous registrations). With this knowledge, an adjustment model for NPR data was constructed to increase the accuracy of fracture registrations (PPV 92%) without excluding valid registrations.
Conclusion: Data from the NPR tend to overestimate the true number of fractures, and proper case selection is needed in order for the data to function as a solid basis for epidemiological research and healthcare planning. In contrast, the SFR constitutes a complete, accurate and efficient source of information.
Keywords: epidemiology, humeral fracture, registers, validation, completeness