Comparability of National Death Index Plus and Standard Procedures for Determining Causes of Death in Epidemiologic Studies

PURPOSE: To determine whether causes of death obtained through National Death Index (NDI) Plus are comparable to those obtained by requesting death certificates from state vital statistics offices and having deaths coded by contractor nosologists. METHODS: The authors compared underlying cause of death codes obtained from NDI Plus with those assigned by contractor nosologists for a sample of 250 known decedents. RESULTS: The underlying cause of death codes differed for 18 (7%) of 249 successful matches. Independent coding by an expert National Center for Health Statistics (NCHS) nosologist trainer revealed that seven of these had an NDI Plus code that matched the code provided by the NCHS nosologist and a contractor nosologist code that did not match the NCHS nosologist code, seven had a contractor nosologist code that matched the NCHS nosologist code and an NDI Plus code that did not match the NCHS nosologist code, and four had both an NDI Plus and a contractor nosologist code that did not match the NCHS nosologist code. The level of disagreement with the NCHS nosologist and the organ systems involved were similar for NDI Plus and the contractor nosologist. CONCLUSIONS: The authors report that NDI Plus provides comparable information within a substantially shorter time period for most states and, for known decedents, at about half the cost of standard procedures.