A Practical Approach to Balancing Data Confidentiality and Research Needs: The NHIS Linked Mortality Files

Abstract

Demand is increasing for statistical agencies to integrate information from different sources and to make such data files publicly available. The National Center for Health Statistics (NCHS) conducts record linkage activities for its surveys, with a major focus being the linkage to the National Death Index. In 2004, NCHS updated the mortality follow-up for the National Health Interview Survey (NHIS) which, because of confidentiality protections, was made available only through the NCHS Research Data Center. In 2007, NCHS released a public-use version of the NHIS Linked Mortality Files. The release of a public-use file was based upon an approach to maximize the amount of mortality information included and minimize the amount of perturbed data, while maintaining the confidentiality protections of survey participants. Comparative analyses between the public-use and restricted-use linked mortality files show that the two data files yield very similar results for both all-cause and cause-specific mortality.