Attrition and retention of ethnically diverse subjects in a multicenter randomized controlled research trial.

Recruitment and retention of subjects is critically important for the conduct of randomized clinical trials. When significant effort is given toward recruiting members of ethnic minorities in a sample, a similar rate of retention for all subgroups of subjects is essential. Little is known about why research subjects withdraw consent to participate in research and whether attrition is influenced by ethnicity or other factors. The purpose of this study was to determine the reasons for withdrawal from a large, multicenter randomized trial and whether these reasons differed among ethnic and gender subgroups. Additionally, we were interested in comparing withdrawn subjects to matched subjects who stayed in the trial to determine what factors encouraged full study completion. Using a cohort survey design, adult subjects (n = 35) who withdrew from a large, multicenter randomized trial and matched subjects who completed the study (n = 35) were interviewed by telephone after study completion. Subjects who withdrew consent tended to be female and members of ethnic minorities. The most frequent problems-reported significantly more often by subjects who withdrew consent compared to matched retained subjects-were interference with work, lack of time, complicated and cumbersome record-keeping requirements, difficult study medicine regimens, and difficulty rescheduling appointments due to lack of flexibility on the part of study personnel. Only 17% of withdrawn subjects were satisfied with the overall research experience compared to 52% of matched retained subjects. Matched subjects who completed all required visits in the randomized controlled trial reported three reasons that promoted completion: remuneration, commitment to finish, and belief that the study was important.

Clinical differences among women with and without self-reported perimenstrual asthma.

BACKGROUND: Studies suggesting that 30% to 40% of asthmatic women report significant perimenstrual (late luteal phase) exacerbations of asthma are primarily retrospective, rely on subjective findings and do not demonstrate a consistent association between asthma and the menstrual cycle. OBJECTIVE: In this exploratory analysis, women with and without self-reported perimenstrual exacerbations of asthma (PMA) were examined prospectively to determine the association between asthma and the menstrual cycle and to characterize associated clinical factors. METHODS: Thirty-two adult asthmatic women with regular menstrual periods recorded daily asthma symptoms, medication use, and peak expiratory flow rate (PEFR) over six consecutive menstrual cycles, and underwent spirometry and methacholine bronchoprovocation during the luteal and follicular phases of 2 cycles. RESULTS: Nine of 32 subjects (28.2%) reported PMA. Daily means of rescue medication use and AM peak flow computed for each perimenstrual day demonstrated significant non-parallelism of group profiles; subjects with PMA had increasing inhaled short acting beta 2-agonist use and decreasing AM peak flow rates during the perimenstrual interval. Luteal-follicular phase differences in FEV1 or methacholine bronchoprovocation between the groups were not detected. Subjects with PMA were older (P=.007), had longer duration of asthma (P=.039), and increased baseline asthma severity (P=.076) compared with subjects without PMA. CONCLUSION: The findings of this study suggest that women with self-reported perimenstrual asthma demonstrate perimenstrual differences in rescue bronchodilator use and AM peak flow and appear to constitute a distinct subset of women with asthma who are older, have longer duration of asthma, and increased severity of asthma compared with women without self-reported perimenstrual asthma. These factors identify women who require close monitoring of their asthma during their menstrual cycles.