Reasons for high retention in pediatric clinical trials: comparison of participant and staff responses in the Correction of Myopia Evaluation Trial

Abstract

The Correction of Myopia Evaluation Trial (COMET), a randomized, multicenter clinical trial of myopia progression in children, had an exceptionally high retention rate of 98.5% (462/469) at three years of follow-up. The present investigation was designed to evaluate and compare the reasons for COMET's high retention rate according to participating families and clinical center staff. Families (n = 411) and staff (n = 35) completed a confidential 19-item questionnaire by indicating families' levels of preference for each item, and rating its importance in keeping families in the study. The questionnaire evaluated study features in four categories: staff characteristics, operational aspects, specific study elements, and incentives. Results showed that most families viewed the study very favorably. Features that appealed to 90% or more families and promoted continued study participation included staff attributes such as friendliness, responsiveness and encouragement, and aspects pertaining to standard of care such as completeness of eye exam, quality of eye care and free eyeglasses. Compared to families, staff tended to underestimate the importance of the following features for retention: seeing the same staff at each visit, appointment reminders, center location, newsletters, commitment to the study, being part of a nationwide study, length of the study, association with a college of optometry, completeness of eye exam, and eye drops (p < 0.05 by chi-square analyses). However, staff responses also revealed less preferred components of the study protocol (e.g., eye drops), to which families might have been reluctant to respond unfavorably. Our findings highlight the importance of intangible factors such as staff attributes and participants' study commitment in maintaining high retention rates, and the usefulness of surveying both families and staff.