The Evolution of the WHI 80+ Cohort.
BACKGROUND
The Women's Health Initiative has collected data on the aging process of postmenopausal women for over two decades, including data on many women who have achieved age 80 years and older. However, there has not been any previous effort to characterize the 80+ cohort and to identify associated retention factors.


METHODS
We include all women at baseline of the Women's Health Initiative who would be at least 80 years of age as of September 17, 2012. We summarize retention rates during the study and across two re-enrollment campaigns as well as the demographic and health-related characteristics that predicted retention. Further, we describe the longitudinal change from baseline in the women identified as members of the 80+ cohort.


RESULTS
Retention rates were lower during each of two re-enrollment periods (74% and 83% retained during re-enrollment periods 1 and 2, respectively) than during the first and second data collection periods (90% each). Women who were retained were more likely to be white, educated, and healthier at baseline. Women age 80 and older saw modest changes in body mass index and depression burden, despite lower physical activity and increased cardiovascular disease.


CONCLUSIONS
The characteristics of women who were retained in the 80+ cohort differ in significant ways compared with their peers at baseline. Identifying the characteristics associated with attrition in older cohorts is important because aging and worsening health has a negative impact on study attrition. Strategies should be implemented to improve retention rates among less healthy older adults.
Department of Biostatistical Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina. dbeavers@wakehealth.edu.
Daniel P
DP
Beavers
Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington.
Mary
M
Pettinger
Department of Biostatistical Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina.
Mark A
MA
Espeland
Department of Biostatistical Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina.
Beverly M
BM
Snively
Department of Biostatistical Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina.
Xiaoyan
X
Leng
Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington.
Julie R
JR
Hunt
Division of General Internal Medicine, University of Pittsburgh, Pennsylvania.
Hilary A
HA
Tindle
Department of Social Science and Health Policy, Wake Forest University, Winston-Salem, North Carolina.
Sally A
SA
Shumaker
D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology* / Q000523:psychology*; D015331:Cohort Studies; D003710:Demography; D005260:Female; D006305:Health Status Indicators; D006306:Health Surveys; D006801:Humans; D010349:Patient Compliance / Q000706:statistics & numerical data*; D010352:Patient Dropouts / Q000706:statistics & numerical data*; D011788:Quality of Life; D014481:United States; D016387:Women's Health
80+ cohort; Aging; Attrition; Retention; Women’s health initiative