Evaluation of a methodology to validate National Death Index retrieval results among a cohort of U.S. service members

Purpose: Accurate knowledge of the vital status of individuals is critical to the validity of mortality research. National Death Index (NDI) and NDI-Plus are comprehensive epidemiological resources for mortality ascertainment and cause of death data that require additional user validation. Currently, there is a gap in methods to guide validation of NDI search results rendered for active duty service members. The purpose of this research was to adapt and evaluate the CDC National Program of Cancer Registries (NPCR) algorithm for mortality ascertainment in a large military cohort.

Methods: We adapted and applied the NPCR algorithm to a cohort of 7088 service members on active duty at the time of death at some point between 2001 and 2009. We evaluated NDI validity and NDI-Plus diagnostic agreement against the Department of Defense's Armed Forces Medical Examiner System (AFMES).

Results: The overall sensitivity of the NDI to AFMES records after the application of the NPCR algorithm was 97.1%. Diagnostic estimates of measurement agreement between the NDI-Plus and the AFMES cause of death groups were high.

Conclusions: The NDI and NDI-Plus can be successfully used with the NPCR algorithm to identify mortality and cause of death among active duty military cohort members who die in the United States.