Validation of Prostate Cancer Diagnosis and Cause of Death in a National Cohort of Male Veterans with Type 2 Diabetes

Background: Accurate diagnosis and cause of death ascertainment are essential for effective disease surveillance and epidemiological research. This study aimed to validate prostate cancer diagnostic accuracy (PCa) and the accuracy of cause of death information among veterans with type 2 diabetes mellitus (T2DM). Methods: We conducted a retrospective cohort study of veterans with T2DM diagnosed during the baseline period (2008–2009) and followed from 2010 to 2019 using data from the Veterans Health Administration (VHA) Corporate Data Warehouse (CDW). Diagnostic codes and cause of death data were obtained from the Prostate Cancer Data Core (PCDC) and the National Death Index (NDI), which served as the gold standards for validating PCa diagnosis and mortality information in the CDW. Concordance between data sources was assessed using Cohen’s Kappa statistic. Results: Among 763,424 veterans with T2DM, 37,048 (4.9%) were diagnosed with PCa in the CDW and 36,861 (4.8%) in the PCDC, with a concordance rate of 36,361 (98.6% of patients diagnosed in the PCDC). Mortality data from the NDI identified 2723 deaths with PCa listed as the underlying cause of death, of whom 75.4% had a corresponding PCa diagnosis recorded in the CDW. For all-cause mortality, 328,165 veterans were identified as deceased in the CDW Vital Status File (VSF), compared with 326,707 deaths recorded in the NDI. Of these, 324,567 deaths were concordant between the two sources, representing 99.3% of NDI-recorded deaths. Compared with the PCDC, the CDW demonstrated high accuracy for identifying incident PCa diagnosis, with a sensitivity of 98.6% and a specificity of 99.9%. Conclusions: The findings demonstrated a high level of concordance in key outcomes, including PCa diagnosis between the CDW and PCDC, and all-cause mortality between the CDW VSF and NDI.