Impact of an in-consult patient decision aid on decisional quality, involvement, and health outcome for patients with severe hip or knee osteoarthritis – a study protocol for a multicentre, cluster randomised controlled trial (PATI-study)

Background: Osteoarthritis (OA) of the hip or knee is a widespread joint disease, often leading to replacement surgery. However, despite the high success rate of replacement surgery, some patients fail to experience the intended benefits. Given the importance of patient involvement, this trial aims to assess the effect of shared decision-making (SDM) on decisional quality for patients with severe OA. Specifically, it investigates whether an in-consult patient decision aid (PtDA) enhances decisional quality, involvement, and health outcomes for patients with severe hip or knee OA. Methods: This protocol outlines a pragmatic two-armed multicentre cluster-randomised controlled trial (C-RCT) involving 19 orthopaedic surgeons randomised 1:1, stratified by centre, to either continue standard consultations or SDM with a newly developed in-consult PtDA. This trial intends to recruit 615 patients diagnosed with severe OA in their hip or knee. Surveys measuring decisional quality and disease-specific and generic health outcomes will be sent out at multiple time points: one-week post-consultation and three and 12 months post-consultation or post-surgery. The primary outcome (decisional quality) will be measured using the Hip/Knee OA Decision Quality Instrument and assessed based on the percentage of patients who are well-informed and receive their preferred treatment. The secondary outcomes include patient involvement in the decision-making process and consultation durations. The tertiary outcomes include patients’ satisfaction, regret and health-related outcomes. Discussion: This study aims to contribute insights into the use of SDM facilitated by a PtDA and its impact on improving decisional quality for future patients with hip or knee OA. Trial registration: www.ClinicalTrials.gov (NCT05972525), Data of registration: 06.08.2023