Benefits of linkage to the National Death Index in the Longitudinal Study of Aging.

To reduce the potential bias resulting from differential loss to follow-up in the Longitudinal Study of Aging (LSOA), information obtained from household contact methods was supplemented with information from the National Death Index (NDI). This article examines the degree of agreement in the vital status data from two sources (reinterview contacts and the NDI system) and evaluates the potential gains of using the NDI data as a supplement to define participants' vital status. Results reveal that NDI information, used to supplement reinterview information, can substantially reduce bias due to the differential loss of participants to follow-up. Reliance on reinterview information alone was less likely to capture those deaths occurring in study participants who at the initial contact lived alone, were below the poverty index, were interviewed without use of a proxy, did not supply a phone number, and did not own a home.