Strategies and procedures to ensure a participant’s retention and adherence to WHI were used throughout the course of the study. In addition to the general retention activities used for all participants, each of the Clinical Trials had special programs to deal with adherence challenges.
Study-wide retention strategies were developed and implemented in four areas:
Promoting participant bonding and affiliation with the study. This was accomplished by mailing semi-annual newsletters to all participants, maintaining a participant website, sending participants periodic updates on study findings, distributing small thank you gifts at annual visits, and including the study logo and catch phrase on materials.
Maintaining current contact information. All mailings requested address corrections from the postal service, and personal contact information (e.g., phone number, address, names of two personal contacts) was updated throughout the study.
Following up and tracing non-responding and lost participants. Follow-up contacts (mailings, phone calls) were made to non-respondents to collect health updates annually and determine vital status. Website tracking services and other strategies were used by local clinic staff to track lost participants.
Adjusting participation level. In order to collect at least minimal health outcomes information on an annual basis, participants could adjust their follow-up status if necessary (e.g., they could provide health updates by phone or through a proxy instead of coming to the Clinical Center for in-person visits).
Dietary adherence was monitored by a food frequency questionnaire (FFQ) developed for the WHI. The design assumption was to achieve an 11%-13% difference in percent energy fat between the control and intervention groups (Control-Intervention; C-I). At year 1, the Control-Intervention difference in % energy from fat was 10.9% and at year 5 it was 9.0%. To support adherence during the long-term maintenance of dietary change, 4 study-wide programs for participants in the Dietary Change (intervention) group were implemented between 1999 and 2004 to augment the core intervention program. Clinical Centers were additionally encouraged to provide augmented programs tailored to their participants.
Adherence to intervention was monitored by weighing study pills returned at each semi-annual or annual visit, before new bottles of pills were dispensed. If a pill collection was not possible (e.g., because a participant forgot to return her study pills), then she was asked to provide an estimate of her remaining pills, not take any more of those pills, and begin taking the newly dispensed pills. If pills were subsequently returned (either by mail or at the next visit), this estimate was updated to reflect the adherence calculation based on returned pill weight.
Adherence challenges, such as having a calculated adherence of less than 80%, were addressed through an “Intensive Adherence Program” (IAP), a series of special non-routine participant contacts. The number, frequency, and content of the contacts varied according to participant need and Clinical Center staff judgment, but at least two contacts with the participant were required: one to initiate the IAP and one to follow-up. IAP contacts included defining the specific nature of the adherence problem, self-monitoring of the problem, identifying solutions for the problem, and following up to see if the solutions worked in either eliminating the problem or making it better. The focus of the IAP was on the behavioral, symptom-related, cognitive, and affective reasons for poor adherence and what to do about them.