Using discreet choice experiments to elicit patient perception of acceptable risk in total knee arthroplasty: study protocol for a randomised controlled trial

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Osteoarthritis (OA) is a leading cause of disability in developed nations. Total knee arthroplasty (TKA) is the mainstay of treatment for people with end-stage knee OA, and represents one of the highest volume medical interventions globally. Despite a high overall success rate with this operation, up to 1 in 3 patients remain dissatisfied following TKA. The reasons for this dissatisfaction include ongoing pain and functional limitation, which patients view as markers of poor outcome following surgery. Research indicates that the strongest predictor of patient dissatisfaction following TKA is unmet expectations. This is known to occur when patients and surgeons have different expectations of surgery. Decision making aids have been effective in aligning patient and surgeon expectations of surgery and improve health outcomes. This study will use a discrete choice experiment (DCE) as a type of decision making aid applied to patients prior to surgery to improve patient knowledge and realistic expectations of TKA. This study will test if this leads to greater health outcome and satisfaction amongst patients following TKA. 132 people with end stage OA on the waiting list for TKA will be recruited and randomly allocated to one of 2 groups using computer-generated block randomisation. A randomised controlled trial (RCT) adhering to CONSORT guidelines will evaluate the effect of applying a DCE prior to surgery on patient expectations, health outcomes and satisfaction following TKA. Patients in the intervention arm will complete a survey containing the DCE decision aiding tool, compared to the control group who will complete a modified survey that does not contain the DCE activity. Participants in both groups will be required to complete the survey prior to surgery during their routine pre-admission appointment at SVHM. Patients will also be required to complete a brief patient expectation survey 1-week prior to scheduled TKR. In addition, orthopaedic surgeons will complete a brief expectations survey for patients consented to TKA to compare matched surgeon and patient expectations for recovery following TKA. Primary outcomes will be evaluated by a blinded examiner at 12 months post-surgery using a validated self-reported pain and physical function scale. Secondary outcomes will include a range of validated measures of health and psychological wellbeing. All analyses will be conducted on an intention to treat basis using linear regression models. This study is the first of its kind to use this approach to elicit risk-benefit tolerance in surgery and to evaluate if guiding patients through a decision making process in the form of a DCE-based survey prior to surgery will improve patient expectations, health outcomes and satisfaction following TKA. Reducing the rate of patient dissatisfaction commonly seen in patients following TKA will help to reduce the burden associated with poor outcomes on the health system.