Quality management of a multi-center randomized controlled feeding trial: A prospective observational study

BackgroundNutrition and dietary trials are often prone to bias, leading to inaccurate or questionable estimates of intervention efficacy. However, reports on quality management practices of well-controlled dietary trials are scarce. This study aims to introduce the quality management system of the Diet, ExerCIse and CarDiovascular hEalth-Diet Study and report its performance in ensuring study quality.MethodsThe quality management system consisted of a study coordinating center, trial governance, and quality control measures covering study design, conduct, and data analysis and reporting. Metrics for evaluating the performance of the system were collected throughout the whole trial development and conducted from September 2016 to June 2021, covering major activities at the coordinating center, study sites, and central laboratories, with a focus on the protocol amendments, protocol deviations (eligibility, fidelity, confounders management, loss to follow-up and outside-of-window visits, and blindness success), and measurement accuracy.ResultsThree amendments to the study protocol enhanced feasibility. All participants (265) met the eligibility criteria. Among them, only 3% were lost to the primary outcome follow-up measurement. More than 95% of participants completed the study, they consumed more than 96% of the study meals, and more than 94% of participants consumed more than 18 meals per week, with no between-group differences. Online monitoring of nutrient targets for the intervention diet showed that all targets were achieved except for the fiber intake, which was 4.3 g less on average. Only 3% experienced a body weight change greater than 2.0 kg, and 3% had medication changes which were not allowed by the study. James' blinding index at the end of the study was 0.68. The end digits of both systolic and diastolic blood pressure readings were distributed equally. For laboratory measures, 100% of standard samples, 97% of blood-split samples, and 87% of urine-split samples had test results within the acceptable range. Only 1.4% of data items required queries, for which only 30% needed corrections.DiscussionThe Diet, ExerCIse and CarDiovascular hEalth-Diet Study quality management system provides a framework for conducting a high-quality dietary intervention clinical trial.