WHI Extension Studies (2005 - Present)
Extension I (2005-2010)
The first WHI Extension Study enrolled 115,400 consenting participants from each of the original WHI study components for an additional five years of follow-up, from 2005 to 2010. The purpose of the additional follow-up was to describe the longer term effects of the original interventions, to document change in hormone use in participants from the Hormone Therapy trials, to expand the range of scientific questions that can be reliably addressed in the WHI, and to provide an infrastructure able to support additional investigations of a very large longitudinal study of postmenopausal women.
WHI participants were invited to join the Extension Study at either the final WHI clinic visit/contact (CT) or in the final annual follow-up mailing (OS). Efforts to recruit women were standardized to avoid differential accrual between randomization groups and components.
Annual updates on health outcomes were collected by mail from the participants enrolled in the Extension Study, using procedures similar to those used to collect follow-up data from Observational Study participants during the initial WHI. Women reporting study outcomes were contacted by WHI field center staff to obtain additional details on health events. Outcomes documentation are then distributed to physician adjudicators who follow existing WHI procedures for adjudicating cases.
Extension II (2010-Present)
The second WHI Extension Study, from 2010 to Present, enrolled 93,500 consenting participants from the first WHI Extension Study for additional follow-up. The primary health outcomes of interest remain as originally defined for the Clinical Trials, with additional emphasis on cardiovascular events and aging. Extension Study participants continue to complete annual data collection forms, primarily by mail. Additional data collection is done via linkage mechanisms with external data sources such as the National Death Index (NDI) and the Center for Medicare/Medicaid Services (CMS).
Only health events occurring in African-American or Hispanic women or former HT trial participants are adjudicated. Thus, the overall WHI study population is divided into two new subsamples, the Medical Records Cohort (MRC) and the Self-Report Cohort (SRC), distinguishing the quality and extent of the outcome information collected.
A subset of the participants in the Medical Record Cohort were invited to participate in a home visit (WHI Long Life Study) in which blood collection, physical measurement, and additional questionnaire data were collected. 7,875 WHI Extension Study participants between the ages of 63 and 99 years old participated in the WHI Long Life Study (LLS) in-person visits between March 2012 and May 2013. See Long Life Study for more detail.
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