The effects of a preference-based exercise trial on outcomes in men on androgen deprivation therapy (ADT) for prostate cancer compared to an exercise randomized controlled trial of the same interventions.
Authors: Alibhai Shabbir M.H. , Papadopoulos Efthymios , Tomlinson George , Durbano Sara , Santa Mina Daniel , Sabiston Catherine , Matthew Andrew , Ritvo Paul , Chiarotto James Anthony , Sidani Souraya , Culos-Reed S. Nicole 
Published: February 2022

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Background: Recruitment for most exercise trials is challenging and often hindered by participants’ inability to travel to the study centre and/or unwillingness to be randomized. Thus, patients in exercise randomized controlled trials (RCTs) are highly selected and may not reflect real-world experiences. Our objectives were to compare baseline characteristics and outcomes of men who agreed to participate in a preference-based trial (PREF) compared to a RCT of the same exercise interventions. Methods: A 2-arm multicentre PREF trial was conducted concurrently with a 2-arm RCT. Participants were men on ADT who were treated at 2 academic and 2 community hospitals in Canada and selected to engage in a group-based in-centre exercise intervention (GROUP) or a home-based exercise program (HOME). All participants underwent aerobic and resistance training 4-5 days per week for 6 months. Co-primary outcomes included fatigue (FACT-F) and the 6-minute walk test (6MWT). Differences at baseline between the two trials were compared using ANOVA. Analysis of covariance with adjustment for baseline value was used to assess differences in the study outcomes between the two trials and between exercise arms. Results: 56 participants (mean age 70 y) consented and selected to participate in GROUP (n = 18) or HOME (n = 38). Recruitment rate was 21.5%. Retention at 6 months in the PREF and RCT was 72.7% and 50%, respectively. No significant differences were observed in baseline characteristics between participants of the two trials. Adherence was met by 60% of participants in PREF. Participants in PREF exhibited a 28.7-metre increase (better) in the 6MWT at 6 months compared to RCT participants ( p = 0.20). Additionally, participants in PREF demonstrated less time (better) to complete 5 chair stands (mean change: -1.24s) at 6 months relative to participants in the RCT irrespective of exercise mode ( p = 0.06). HOME participants in the PREF completed the 5 chair stands faster (mean change: -2.19s) compared to HOME participants in the RCT (p = 0.01). Similarly, GROUP participants in the RCT required less time (mean change: -2.11s) for 5 chair stands compared to GROUP participants in the PREF (p = 0.04). Hip circumference was higher (worse) at 6 months in PREF participants (mean change: +2.95cm) compared to their RCT counterparts (p = 0.02). Although fatigue was not significantly different between participants in the two studies at 6 months, GROUP participants in the RCT experienced worse fatigue (mean change: -6.93) compared to those who selected GROUP (p = 0.03). Conclusions: Allowing participants to select the exercise intervention of their preference may improve retention and ameliorate functional declines as a result of ADT. Further studies that assess the effects of preference-based trials on clinical outcomes are warranted. Clinical trial information: NCT03335631.