WHI Extension Study
Overview
The WHI Extension Study enrolled consenting participants from each of the original WHI study components for an additional five years of follow-up, from 2005 to 2010. Annual updates on health outcomes are collected by mail from the 115,400 participants enrolled in the Extension Study. The purpose of the additional follow-up is 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 requiring some of the unique features of a very large longitudinal study of postmenopausal women.
Follow-up
All Extension Study participants complete annual data collection forms primarily by mail, using procedures similar to those used to collect follow-up data from Observational Study participants during the initial WHI. Women reporting study outcomes are contacted by WHI field center staff to obtain additional detail on health event dates and providers, and a signed release to obtain medical records, if needed.
All Extension Study participants receive an annual Form 33 – Medical History Update by mail; women reporting study outcomes that require documentation are contacted by field center staff to complete a Form 33D – Medical History Update (Details). All participants also receive an annual Form 151 - Activities of Daily Life, and completed a one-time Form 134 - Medical History Update Addendum.
DM-specific follow-up
A 4.6% subsample of women who were in the WHI Dietary Modification Trial are asked to complete one 24-hour recall during the Extension Study. Half of the subsample completed the recall toward the start of the Extension Study (around 2006-2007) and half toward the end (2009-2010).
HT-specific follow-up
Participants who were in the Hormone Therapy Trial also complete a Form 150 - Hormone Use Update annually. For the first two years of extension follow-up, WHI field centers collected annual mammography reports for HT participants.