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Activity Number:
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440
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Type:
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Contributed
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Date/Time:
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Wednesday, August 5, 2009 : 8:30 AM to 10:20 AM
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Sponsor:
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Section on Statistics in Epidemiology
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| Abstract - #303818 |
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Title:
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A Two-Component Mixture Model for Characterizing the Age Distribution of Pertussis Infant Mortality in the United States
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Author(s):
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Andrew L. Baughman*+ and Tracy Pondo and Barry Sirotkin and Tejpratap Tiwari and Charles E. Rose and Margaret M. Cortese
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Companies:
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CDC and CDC and CDC and CDC and CDC and CDC
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Address:
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1043 N. Virginia Ave., Atlanta, GA, 30306,
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Keywords:
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negative binomial ; mixture model ; age distribution ; pertussis ; infant mortality
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Abstract:
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Given the decline in U.S. infant pertussis deaths before universal childhood vaccination started in the mid-1940s and the increase in deaths in the 1990s, examination of longer-term trends is warranted. We summarized data on pertussis deaths in single months of age at death (0--11) from U.S. vital statistics for 1933--2004. A two-part mixture model was developed that included a point distribution for deaths that occurred in the first month of life, and a doubly truncated negative binomial distribution for deaths that occurred during months 1 to 11. Results from fitting the mixture model indicated that the average age at death decreased from 4.5 months in 1933--1944 to 1.9 months in 1985--2004. Following the introduction of universal pertussis vaccination, the age distribution of pertussis deaths shifted downward to infants who are too young to be adequately protected by vaccination.
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