Coenrollment in a randomized trial of high-frequency oscillation: prevalence, patterns, predictors, and outcomes*.

OBJECTIVE: Enrollment of individual patients into more than one study has been poorly evaluated. The objective of this study was to describe the characteristics of patients, researchers and centers involved in coenrollment, studies precluding coenrollment, and the prevalence, patterns, predictors, and outcomes of coenrollment in a randomized clinical trial. DESIGN, SETTING, METHODS: We conducted an observational study nested within the OSCILLation for Acute Respiratory Distress Syndrome Treated Early Trial, which compared high-frequency oscillatory ventilation to conventional ventilation. We collected patient, center, and study data on coenrollment in randomized patients. Multilevel regression examined factors independently associated with coenrollment, considering clustering within centers. We examined the effect of coenrollment on safety and the trial outcome. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Overall, 127 of 548 randomized patients (23.2%) were coenrolled in 25 unique studies. Coenrollment was reported in 17 of 39 centers (43.6%). Patients were most commonly coenrolled in one additional randomized clinical trial (76; 59.8%). Coenrollment was less likely in older patients (odds ratio, 0.87; 95% CI, 0.76-0.997), and in ICUs with greater than 26 beds (odds ratio, 0.56; 95% CI, 0.34-0.94), and more likely by investigators with more than 11 years of experience (odds ratio, 1.73; 95% CI, 1.06-2.82), by research coordinators with more than 8 years of experience (odds ratio, 1.87; 95% CI, 1.11-3.18) and in Canada (odds ratio, 4.66; 95% CI, 1.43-15.15). Serious adverse events were similar between coenrolled high-frequency oscillatory ventilation and control patients. Coenrollment did not modify the treatment effect of high-frequency oscillatory ventilation on hospital mortality. CONCLUSIONS: Coenrollment occurred in 23% of patients, commonly in younger patients, in smaller centers with more research infrastructure, and in Canada. Coenrollment did not influence patient safety or trial results.

Review of retention strategies in longitudinal studies and application to follow-up of ICU survivors.

OBJECTIVE: To review the literature on retention strategies in follow-up studies and their relevance to critical care and to comment on the Toronto experience with the acute respiratory distress syndrome (ARDS) and severe acute respiratory syndrome (SARS) follow-up studies. DESIGN AND SETTING: Literature review and two cohort studies in a tertiary care hospital in Toronto, Canada. PATIENTS AND PARTICIPANTS: ARDS and SARS patients. MEASUREMENTS AND RESULTS: Review articles from the social sciences and medicine are summarized and our own experience with two longitudinal studies is drawn upon to elucidate strategies that can be successfully used to attenuate participant drop-out from longitudinal studies. Three key areas for retention of subjects are identified from the literature: (a) respect for patients: respect for their ideas and their time commitment to the research project; (b) tracking: collect information on many patient contacts at the initiation of the study and outline tracking procedures for subjects lost to follow-up; and (c) study personnel: interpersonal skills must be reinforced, flexible working hours mandated, and support offered. Our 5-year ARDS and 1-year SARS study retention rates were 86% and 91%, respectively, using these methods. CONCLUSIONS: Strategies to reduce patient attrition are time consuming but necessary to preserve internal and external validity. When the follow-up system is working effectively, researchers can acquire the necessary data to advance knowledge in their field and patients are satisfied that they have an important role to play in the research project.