Validation of US CDC National Death Index mortality data, focusing on differences in race and ethnicity

ObjectivesThe US Center for Disease Control and Prevention’s National Death Index (NDI) is a gold standard for mortality data, yet matching patients to the database depends on accurate and available key identifiers. Our objective was to evaluate NDI data for future healthcare research studies with mortality outcomes.MethodsWe used a Kaiser Permanente Mid-Atlantic States’ Virtual Data Warehouse (KPMAS-VDW) sourced from the Social Security Administration and electronic health records on members enrolled between 1 January 2005 to 31 December 2017. We submitted data to NDI on 1 036 449 members. We compared results from the NDI best match algorithm to the KPMAS-VDW for vital status and death date. We compared probabilistic scores by sex and race and ethnicity.ResultsNDI returned 372 865 (36%) unique possible matches, 663 061 (64%) records not matched to the NDI database and 522 (