Positive predictive value of humeral fractures in the Danish National Patient Registry

INTRODUCTION. The purpose of this study was to validate the humeral fracture diagnoses for adults in the Danish National Patient Registry (DNPR). METHODS. This was a population-based validity study, including adult patients (= 18 years) with a humeral fracture referred to the emergency department of hospitals in three Danish regions from March 2017 to February 2020. Administrative data were retrieved on 12,912 patients from the databases of the involved hospitals. These databases hold information on discharge and admission diagnoses, which is based on the International Classification of Diseases, tent version. Data of 100 cases were randomly sampled from each of the specific humeral fracture diagnoses (S42.2-S42.9). The positive predictive value (PPV) was estimated for each diagnosis to study the recorded accuracy. Radiographic images from the emergency departments were reviewed and assessed as the gold standard. The PPVs with 95% confidence intervals (CI) were estimated according to the Wilson method. RESULTS. In total, 661 patients were sampled between all available diagnosis codes. Overall, the PPV for humeral fracture was 89.3% (95% CI: 86.6-91.4%). PPVs for the subdivision codes were 91.0% (95% CI: 84.0-95.0%) for proximal humeral fractures, 89.0% (95% CI: 81.0-94.0%) for humeral diaphyseal fractures and 78.0% (95% CI: 68.9-84.9%) for distal humeral fractures. CONCLUSION. The validity of the humeral fracture diagnosis and the classifications of proximal and diaphyseal fractures in the DNPR is high, and the DNPR may therefore be used in registry research. Diagnosis of distal humeral fractures has a lower validity and should be used with caution.