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Recruitment and retention of an adequate number of study participants are critical to the success of any clinical trial, because power to detect a difference after intervention is based on sample size, effect size, and a priori alpha level. Recruitment is a problem in most clinical trials (Ashery & McAuliffe, 1992; Swanson & Ward, 1995). Gotay (1991) estimates that less than 3% of oncology patients enter into clinical trials of medical or surgical therapies. Comparable estimates of accrual rates in clinical trials of psychosocial interventions are not available. Once accrued, retention of families is essential because attrition is financially costly and threatens both the internal and external validity of results.
Conducting family research using a longitudinal design and accessing women recently diagnosed with breast cancer challenge the attainment of target sample size. The recent downsizing of health care services, with subsequent instability in nursing staff positions, as well as competition with other large-scale clinical trials accessing the same population further increase the likelihood of inadequate sample size. The purposes of this article are to report the recruitment and retention experiences of project personnel in the Family Home Visitation Program: Nurse as Coach project, to review subject accrual and retention issues identified from our experiences and other researchers, and to suggest specific strategies to maximize sample size for future clinical trials involving families.
The Family Home Visitation Program: Nurse as Coach was a 3-year (1992-1995), National Cancer Institute-funded, multisite, randomized clinical trial of a nursing intervention (Lewis, 1992). The study tested the effectiveness of a home-based intervention program for child-rearing families experiencing nonmetastatic breast cancer in the mother. The therapeutic goal of the intervention was to facilitate the family's management of the impact of the mother's illness on the family. The intervention was delivered in the home to women with recently diagnosed (within 8 months) early-stage (Stage 0, I, or II) breast cancer and their husbands or male partners. The 10-month longitudinal design is illustrated in Figure 1.
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ACCRUAL AND RETENTION IN THE FAMILY HOME VISITATION PROGRAM
An estimation of the target population was based on incidence of noninvasive breast cancer in the recruitment counties in women ages 25 to 54 years in western Washington. Not all women within this estimated population would be referred, eligible, or willing to participate. Our goal was to accrue a total of 200 families enrolled over a 2-year period, randomly assigned to coached (intervention) or evaluation (control) groups. This target sample size was a conservative one, which allowed for attrition of 30% and still provided a power of .80 with a p = .05 of detecting significant clinical differences between the two groups. As a result of our efforts to accrue and retain families, we successfully attained our target sample size.
To maximize the number of participating women, two study sites were used (Seattle, Washington, and Portland, Oregon). University of Washington Human Subjects Review approval was obtained prior to seeking agency-specific institutional review board approval and before recruitment of any participants into the trial. Recruitment was the responsibility of the principal investigator (Lewis) as well as the university-based project manager in Seattle (Motzer) and community-based site coordinator in Portland (Moseley). A total of 313 referrals of women meeting eligibility criteria were made, with 217 families accrued (Seattle n = 156; Portland n = 61); 181 (83.4%) families completed participation, and 36 (16.6%) families did not finish the study. The disposition of all 313 referred eligible families is illustrated in Figure 2 and summarized by randomization and by recruitment site in Table 1.
TABLE 1: Referred Eligible Families (N = 313) by Randomization and by Site Retained Dropped/Withdrew (n = 181) (n = 36) Site Coached Evaluation Coached Evaluation Seattle 60 68 19 9 Portland 24 29 5 3 Total 84 97 24 12 Refused (n = 96) Site Coached Evaluation Seattle 41 43 Portland 6 6 Total 47 9
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Of the 36 families not completing participation, 11 (5.1%) were lost through changes in eligibility criteria or scheduling error, and 25 (11.5%) elected to withdraw (Table 2). These families all had signed the written informed consent and completed at least one in-home visit. Examples of changes in eligibility criteria included loss of partner through divorce and disease progression with distant metastases. The single scheduling error that occurred involved the erroneous completion of the second occasion of data collection prior to completion of the last intervention visit. Families were considered to be refusals if they initially declined to participate or if they subsequently declined prior to signing informed consent and completing the first in-home visit. Reasons for families refusing to participate are summarized in Table 3.
TABLE 2: Reasons for 36 Families Not Completing Participation in the Family Home Visitation Program Number (Percentage of Reason Total Accrued) Change in eligibility status 10 (4.6%) Divorce, dissolution of partnered relationship 5 Recurrence with 2 Stage III disease 2 Disease progression with distant metastases 2 Death of partner 1 Evaluation and coached visits scheduled out of sequence 1 (0.5%) Chose to withdraw from participation 25 (11.5%) Not enough time to participate(a,b) 7 Study did not meet needs(c) 5 Additional stress created by study(a) 5 Chose not to schedule subsequent visits in a timely fashion(d) 2 Family moved out of area and chose not to complete questionnaires by mail(d) 2 Considered themselves "too private" to continue(c) 2 Survey too long or too complicated(a) 2 (a.) Categories of responses were predetermined by researchers. (b.) Time constraints were the result of early-stage breast cancer recurrence for two of these seven families. (c.) Categories were derived by researchers from families' verbatim responses. (d.) We chose to drop these families as we either could not schedule subsequent visits or they did not return questionnaires within study timelines. TABLE 3: Reasons for 96 Referred Families Refusing to Participate in the Family Home Visitation Program Reason Number Mother interested, partner refused(a) 28 Not enough time to participate(a) 26 Mother did not want to participate or be bothered(a) 17 Decided against participating after initial verbal agreement(b) 9 Mother felt study would create additional problems or worries(a) 8 Mother wanted to move past the breast cancer(c) …