​​W25 - WHI Coronary Artery Calcification Study in E-alone (WHI-CACS)

This page provides study documentation for Core Study W25.  


Investigator Names and Contact Information:

This was a WHI Core study approved in 2005 by WHI Steering Committee and Project Office.

Matt Allison at the University of California, San Diego, is the Principal Investigator (mallison@ucsd.edu).



The WHI Coronary Artery Calcium Study (WHI-CACS) is a sub-study of the WHI E-Alone Clinical Trial that aimed to assess the status of coronary atherosclerosis among women aged 50-59 years at baseline in the Estrogen-Alone trial. The study used electron beam computed tomography (EBCT) or multi-detector computed tomography (MDCT) to assess the presence and extent of calcification due to atherosclerosis in the coronary arteries. This measurement allowed for a comparison of atherosclerotic burden among women who had been randomized to estrogen-alone compared to women randomized to placebo after a mean of 7.1 years of treatment.

The operational goal of the study was to complete these measurements on 450 women randomized to estrogen-alone and on 450 women randomized to placebo at the 28 participating Clinical Centers (CCs). A total of 1,781 E-Alone women were eligible at these CCs and were invited to participate in this sub-study. The enrollment target was a maximum of 950 participants to ensure that complete calcium measurements would be available on at least 900 eligible women. A total of 1,141 women consented to the study, and coronary arterycalcium scans were completed on 1,074. The primary analyses were based on "intention-to-treat" and secondary ("sensitivity") analyses limited to women with good adherence to study pills (>80% adherence). The strategy was to complete the scans by July 29, 2005 to ensure that measurements were obtained as soon as possible after discontinuation of study medications, in order to minimize the dilution of treatment effect.

For additional details, please refer to the WHI-CACS Manual and other study documents under Study Documentation.


See publications: 503, 506, 570, 591, 816, 955. WHI publications by study lists published WHI papers that have been generated by ancillary studies. A complete list of WHI papers is available in the Bibliography section of this website.