Preference and participation in a randomized controlled trial of self-management support.

OBJECTIVE: This study examines socio-demographic and healthcare-related factors associated with recruitment and participation in a large randomized controlled trial (RCT) of telephone-based self-management support. METHODS: This register-based study included 78,861 individuals identified as being at risk of future hospital admissions and invited for eligibility assessment for the Danish Proactive Health Support (PaHS) RCT (2018-2022). National registers provided data on socio-demographics, chronic disease burden, and healthcare utilization prior to recruitment. Multivariate logistic regression was used to analyze factors associated with successful contact and subsequent consent to participation. RESULTS: Half of the invited population (51%) was never reached despite repeated attempts. Successful contact was more likely among older individuals, those who were married, had higher educational attainment, chronic diseases, and higher healthcare utilization. Among the 11,109 individuals deemed eligible and informed, 55% consented to participate. In contrast to the contact phase, increasing age was strongly associated with lower likelihood of consent. Individuals with multimorbidity and higher healthcare utilization were significantly more likely to consent to participation. Socio-demographic factors were not independently associated with consent after contact was established. CONCLUSION: Recruitment to self-management support involves a selection process, where inequities arise primarily during initial contact attempts where older adults and socially vulnerable groups were less likely to be reached. After successful contact, patients with greater healthcare needs were more likely to participate. PRACTICE IMPLICATIONS: Recruitment to self-management support interventions involves a selection process in which inequities may arise before eligibility is fully assessed. Efforts to improve participation should therefore consider not only eligibility criteria but also factors influencing successful contact and willingness to participate. The findings challenge the distinction between eligibility and consent in self-management interventions and underscore the need to reconsider patient preferences and readiness as dynamic, context-dependent factors in intervention design.