Troels Munch, Lotte B Christensen, Kasper Adelborg, Grethe S Tell, Ellen M Apalset, Anna Westerlund, Ylva T Lagerros, Johnny Kahlert, Fei Xue, Vera Ehrenstein

Validation of definitions used to identify conditions of interest is imperative to epidemiologic studies based on routinely collected data. The objective of the study was thus to estimate positive predictive values (PPVs) of International Classification of Diseases, 10th Revision (ICD-10) codes to identify cases of incident acute pancreatitis leading to hospitalization and incident primary malignancy in the Scandinavian (Denmark, Norway, and Sweden) national patient registries in women with postmenopausal osteoporosis (PMO). This validation study included postmenopausal (defined as 55 years or older) women with osteoporosis, identified between 2005-2014. Potential cases were sampled based on ICD-10 codes from the three national patient registries. Cases were adjudicated by physicians, using medical record review as gold standard. PPVs with corresponding 95% CIs were computed. Medical records of 286 of 325 (retrieval rate 88%) women with PMO were available for adjudication. Acute pancreatitis leading to hospitalization had a PPV of 87.6% (95% CI: 80.8%-90.2%). Incident primary malignancy had a PPV of 88.1% (95% CI: 81.3%-92.7%). The PPVs did not vary substantially across the three countries. ICD-10 codes to identify acute pancreatitis leading to hospitalization, and incident primary malignancy in the Scandinavian national patient registries had high PPVs among women with PMO. This allows identification of cases of acute pancreatitis and incident primary malignancy with reasonable validity and to use these as outcomes in comparative analyses.