RE: "COMPARISON OF NATIONAL DEATH INDEX AND WORLD WIDE WEB DEATH SEARCHES"
Mark E. Hill
Population Research Institute The Pennsylvania State University University Park, PA 16802-6210
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INTRODUCTION
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In their recent study using data from the College Alumni Health Study, Sesso et al. provided a valuable assessment of the Social Security Administration's Death Master File (1
). However, several clarifications are warranted.
As part of a study we conducted to explore age misreporting at older ages, several coauthors and I attempted to link a sample of 12,980 death certificates to the Death Master File for White decedents who died in 1985 at age 85 years or older (2
). By using computerized and manual linkage procedures, we successfully identified 92.7 percent of our decedents in the Death Master File. Sesso et al.'s (1
) findings for men are comparable with ours: 94.7 percent of male decedents from the College Alumni Health Study were identified in the Death Master File compared with 95.1 percent in our study. However, fully 68.9 percent of the female decedents from this study could not be located in the Death Master File, which compares with only 8.5 percent in our study.
The fact that search procedures for the College Alumni Health Study required agreement on first and last names probably explains the dramatically weaker linkage results for women when compared with our findings. Indeed, subjects whose names in the Death Master File differed substantially from the names recorded previously in the College Alumni Health Study data could not be identified successfully. Because name changes disproportionately involve women, the authors (1
) apparently failed to identify a majority of their women decedents in the Death Master File. Our study was less sensitive to this problem because we had a valid social security number for over 95 percent of the sample, and our primary linkage procedure relied heavily on agreement of the social security number in both files (although we never considered linkage of the social security number alone to be sufficient evidence of a successful match).
In another vein, the authors (1
) appear to be mistaken when they say that the Death Master File identifies only those persons for whom the Social Security Administration has paid lump-sum death benefits. On the contrary; a recent publication by the Office of the Inspector General of the Social Security Administration states that the Death Master File contains deaths reported from a variety of sources (3
). Since 1988, the Social Security Administration's official repository of death information has been the NUMIDENT, a master file containing identifying information for all persons assigned a social security number. Relatives of deceased persons, funeral directors, financial institutions, and postal authorities are the primary sources of death information recorded in the NUMIDENT. Additional deaths are also identified from computer files provided by a variety of government agencies. Death information is extracted from the NUMIDENT regularly to create updated versions of the Death Master File for public distribution.
When funding levels permit, both the Death Master File and the National Death Index can be used to enhance the advantages of each. For example, researchers relying solely on the National Death Index for mortality ascertainment will almost certainly fail to identify some proportion of actual decedents because of inconsistencies in the reporting of identifying information on death certificates. Hence, use of Social Security Administration data in concert with the National Death Index has been shown to substantially improve the completeness of mortality ascertainment in longitudinal studies (4
). Furthermore, while the Death Master File includes persons enrolled with the Social Security Administration who died in foreign countries (e.g., Americans dying abroad or immigrants who have returned to their countries of origin), the National Death Index is limited to deaths occurring in the United States, Puerto Rico, and the Virgin Islands. Smith reports that by using Social Security Administration death data, the Alameda County Study was able to identify deceased study subjects in Spain, Norway, and the Philippines (5
). Finally, because of the high cost of National Death Index compared with Death Master File searches, cost-effective two-stage search protocols might be developed that reserve the more expensive National Death Index searches for study subjects not located during initial searches of the Death Master File.
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NOTES
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Editor's note: In accordance with Journal policy, Sesso et al. were asked whether they wished to respond to this letter, but they chose not to do so.
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REFERENCES
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Sesso HD, Paffenbarger RS, Lee IM. Comparison of National Death Index and World Wide Web death searches. Am J Epidemiol 2000;152:10711.[Abstract/Free Full Text]
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Hill ME, Preston SH, Rosenwaike I. Age reporting among white Americans aged 85+: results of a record linkage study. Demography 2000;37:17586.[ISI][Medline]
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Improving the usefulness of Social Security Administration's Death Master File. (Evaluation report). Woodlawn, MD: Office of the Inspector General, Social Security Administration, July 2000. (Publication A-09-98-61011).
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Kraut A, Chan E, Landrigan PJ. The costs of searching for deaths: National Death Index vs Social Security Administration. (Letter). Am J Public Health 1992;82:7601.
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Smith MW. Identifying deaths using the Social Security Administration Death Master files. (Letter). Epidemiology 1997;8:670.