The adapted Zelen was a feasible design to trial exercise in myeloma survivors.

Abstract Objective We utilised a method rarely seen in cancer behavioural trials to explore methods of overcoming difficulties often seen in randomised controlled trials. We report our experiences of the adapted-Zelen design, so that other researchers can consider this approach for behavioural trials. Study Design & Setting:The adapted-Zelen design was used to explore the effects of exercise on multiple myeloma patients fatigue, quality of life and physical outcomes. All participants consented to an observational cohort study of lifestyle factors, but were unaware of subsequent randomisation to remain in cohort only group or be offered an exercise intervention requiring second consent. Results Due to lower than expected uptake rate to the exercise offered group (57%), the length of recruitment increased from 24 to 29 months to ensure power was reached. At enrolment patients were unaware of the potential increased commitment and as a result 62% of participants allocated to the intervention declined due to the extra time/travel commitment required. This emulates clinical settings and suggests improvements in intervention delivery are required. Dropout rates from the cohort only group were similar to designs that provide the control with the intervention. Our results from the main study do not suggest contamination occurred despite some anecdotal evidence. Conclusion Future use of this design warrants careful consideration of the study resources and recruitment time frames required but holds potential value in reducing contamination, control group dissatisfaction and resulting drop out. Adapted-Zelen design reduces selection bias and therefore gives clinicians a better understanding of acceptability in clinical settings. Future studies should evaluate control group experiences of the design and formally record contamination throughout the study to confirm its acceptability.