Long-term dietary intervention trials: critical issues and challenges Full Text
Crichton GE et al. – Attrition and adherence to study requirements present challenges to trials requiring longer–term dietary change. Including a run–in period to further assess the motivation, commitment and availability of participants, maintaining regular contact with participants during control phases, minimising time commitment, providing flexibility with dietary requirements, facilitating positive experiences, and stringent monitoring of diet are some key recommendations for future dietary intervention trials.Methods
- A 12–month, randomised, two–way crossover study in overweight adults with habitually low dairy food consumption designed to assess the effects of a high dairy intake (HD; 4 serves of reduced fat dairy per day) compared to a low dairy intake (LD; 1 serve of reduced fat dairy per day) on measures of cardiometabolic and cognitive health was conducted.
- On completion of the HD phase, each participant was interviewed about their experience in the trial and responses were used to evaluate the key issues for study participants.
- Although the recruitment target was achieved, high rates of attrition (49.3%) and difficulties maintaining participant compliance (reported by 37.8% of participants) were major threats to the viability of the study.
- Factors that contributed to the high attrition included inability to comply with the dietary requirements of the study protocol (27.0%), health problems or medication changes (24.3%) and time commitment (10.8%).