Period Mortality Rates Acknowledgments
7 Discussion
Age-specific mortality data for the elderly in the United States is generally considered to be of poor quality [8]. The primary sources for this data are the decennial census and death registration. The census data have been inconsistent, though Shrestha and Preston [25] identify underreporting in 1970 as the primary source of problems. In this paper we examined sets of cohort and period age-specific mortality rates calculated from the Medicare Enrollment Data Base, an extremely large administrative base. We compare the mortality curves across regions within race and sex groups, and we compare national mortality curves of white men and women relative to black and Puerto Rican men and women. The Medicare EDB is a promising source of age-specific mortality data at oldest ages, but questions remain about the age-specific mortality patterns of blacks, especially black men.

We compared mortality curves across regions and among cohorts for evidence of consistency. There has been a debate focused on the black crossover in age-specific mortality at older ages, a pattern found in these data. There are two primary arguments. The first holds that this pattern is real and reflects the selection of less frail blacks relative to white Americans by age 80 or so [10]. The second argument is that the crossover is an artifact of age misreporting [2]. Any crossover pattern between regions within the same race and sex would also suggest age misreporting.

Both the period and cohort age at death data for whites in the Medicare EDB appear to be very consistent, at least up to age 95, perhaps higher for women. Above age 100 the patterns become extremely inconsistent.

Both cohort and period mortality curves of white women and men showed great consistency across regions. Some regions had lower mortality rates, but there was little year-to-year variation and no mortality crossover. Where inconsistencies occurred, they were primarily from the western regions of the U.S. that had small populations when social security numbers, which is the regional identifier, were issued to this population.

The African-American mortality crossover is found in every period and cohort comparison of the national population. This crossover pattern is remarkably consistent, occurring at ages 85 or 86 in every cohort and period comparison. Recall that Kestenbaum [10] examined this issues using the EDB for specific years, concluding that the pattern was real and that the age data were accurate. However, mortality rates by the mid-90s for black men drops below the mortality rates of white women, a pattern that is unlikely.

The regional patterns for both black men and women show considerable variation over time. This is especially so for men. While we limited this regional comparison to regions with significant black populations, the variations could have been a function of size. Indeed, at the national level, the period mortality patterns of black women are smoothed considerably. The patterns for men remain inconsistent.

This data set is not sufficient to determine whether the black mortality crossover is real or due to age misreporting. And the considerable inconsistency across regions also creates concern about these data. When aggregated at the national level, the mortality curves for black women may be okay up to age 90. In general, we conclude that further examination of the black data is necessary before using them for substantive analysis.

The mortality curves of Puerto Rican men and women are not smooth. That is, they are not consistent from year to year, but rise and fall. However, these year-to-year variations are not large and may simply reflect the relative size of the population. The comparison of the pattern of white American with Puerto Ricans does not reveal a cross-over, but indicates that Puerto Rican mortality rates for both men and women are basically the same or lower than the rates for whites. Again, reasons for these patterns are not clear, but this is a pattern reported in previous research. The annual variations and the relatively low mortality patterns lead us to conclude that these data should be used with caution until further examinations can be conducted.

Considering the magnitude of size of the Medicare EDB, that it captures the majority of the elderly population of the U.S., and that it contains birth and death information, it is clearly a valuable resource for evaluating the age patterns of mortality among older Americans, particularly for older white Americans. It is unlike any other database currently available for research of this kind and its value cannot be overemphasized. However, we recognize the limitations of the database, in particular the concerns it has raised over the black age-at-death data. Certainly, more research can be done to investigate these concerns to determine the nature of the mortality patterns that emerge for black Americans. Given its limitations, the Medicare EDB should be only one of many tools included in further investigations.

Period Mortality Rates Acknowledgments

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Evaluation of U.S. Mortality Patterns at Old Ages
Using the Medicare Enrollment Data Base.

Allan M. Parnell and Cynthia R. Owens
1999 - 2000 Max-Planck-Gesellschaft ISSN 1435-9871