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Randomized Controlled Trial
. 2009 Winter;34(4):145-55.
doi: 10.3200/BMED.34.4.145-155.

Predictors of adherence in the Women's Health Initiative Calcium and Vitamin D Trial

Affiliations
Randomized Controlled Trial

Predictors of adherence in the Women's Health Initiative Calcium and Vitamin D Trial

R Brunner et al. Behav Med. 2009 Winter.

Abstract

The authors analyzed data from the Women's Health Initiative (WHI) Calcium and Vitamin D Supplementation Trial (CaD) to learn more about factors affecting adherence to clinical trial study pills (both active and placebo). Most participants (36,282 postmenopausal women aged 50-79 years) enrolled in CaD 1 year after joining either a hormone trial or the dietary modification trial of WHI. The WHI researchers measured adherence to study pills by weighing the amount of remaining pills at an annual study visit; adherence was primarily defined as taking > or = 80% of the pills. The authors in this study examined a number of behavioral, demographic, procedural, and treatment variables for association with study pill adherence. They found that relatively simple procedures (ie, phone contact early in the study [4 weeks post randomization] and direct social contact) later in the trial may improve adherence. Also, at baseline, past pill-use experiences, personal supplement use, and relevant symptoms may be predictive of adherence in a supplement trial.

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