Title: Introducing Standardized and Evidence Based Thresholds for Hip and Knee Replacement Surgery -The Arthroplasty Candidacy Help Engine (The ACHE tool)
Funder: Department of Health (England)

Abstract: Data from the NHS has shown 2 major problems in the patient pathway for hip and knee replacement; (1) the NHS Atlas of Variation has demonstrated marked unwarranted variation in clinical practice within the UK and (2) 10-15% of patients are dissatisfied with their surgery possibly due to intervention being offered at an early stage of the disease where less benefit is likely. These problems have demonstrated a worrying lack of consistency across this patient pathway in the way care is delivered. Many PCTs have attempted to improve the situation by introducing thresholds for referral. However they are not validated and non-systematic introduction has produced greater levels of variation confounding the situation. We propose that a standardised approach to assessment of patients for hip and knee replacement can be achieved by introducing an evidence based clinical tool to identify patients who are candidates for surgery based on their capacity to benefit. The tool called the Arthroplasty Candidacy Help Engine (ACHE) will combine an established scoring system and a set of evidence based thresholds for treatment. Applying the ACHE tool would allow selection of patients with the capacity to improve whilst protecting patients without such capacity from unnecessary surgical intervention. The tool would be used by GPs to guide referral of patients from Primary to Secondary care but could also be used in Secondary care to confirm continued candidacy for surgery.We will form a USER Group with input from all stakeholders (Patients GPs Consultants & Commissioners) who will be actively involved in all work-packages.Work-package 1 (WP 1): Identification of pre-existing assessment tools that could be used to create referral thresholds for hip and knee replacement surgery.WP 1.1: A literature review to identify and compare candidate assessment scores already available to assess patients prior to joint replacement establishing their reliability in measuring a patient’s pre-operative disease burden capacity to benefit from joint replacement and their potential use in threshold setting.WP 1.2: Use of existing datasets to further assess and develop the candidate scores prior to creating thresholds for hip & knee replacement. By collaboration we have successfully secured access to a large number of data sets of patients undergoing hip & knee replacement (n=190000). A team of two statisticians will analyze the data to further characterize the measurement properties of candidate tools (construct validity reliability responsiveness) and the scores’ ability to measure pre-operatively an individual patient’s capacity to benefit from surgery (response to change minimally important clinical difference). Work-package 2: Creation of the Arthroplasty Candidacy Help Engine (ACHE) tool with thresholds for referral based on capacity to benefit and health-economic benefit.WP 2.1: We will define thresholds for each candidate score in a number of different ways; (1) An upper pre-operative absolute threshold above which no benefit exists for the patient using: change score patient satisfaction minimum clinically important difference and ROC curve analysis cut points to define good outcome. (2) We will validate thresholds using patients’ and clinicians’ ratings of perceived need for joint replacement as an anchor and relating this to their measured pre-operative score. ROC analysis would then be employed to determine different cut points for thresholds. We believe there will be differences in the thresholds calculated for hip & knee. (3) We will generate user friendly pre-operative thresholds as patient reference information establishing the likelihood expressed as a % of improving not improving or remaining the same post surgery for different pre-operative scores (4) We will explore the effect of other co-variables on the thresholds calculated based on assessment scores.WP 2.2: We will establish the effect of threshold values on the cost effectiveness of hip and knee replacement. We will model how post-operative quality of life (QALY) gains from joint surgery and the cost of surgery and subsequent management vary with different preoperative threshold scores. A more complex model of care than previously used will be created using datasets of pre- and post-operative EQ-5D or SF-6D utility and data on NHS resource use (including duration of surgery and inpatient stay joint components revision surgery outpatient follow-up treatment costs for non-operative care of un-operated patients). The model will be used to calculate the total cost and total number of QALYs accrued by each intervention.WP 2.3: The outcome of WP2 will be the creation of the Arthroplasty Candidacy Help Engine (ACHE) tool combining the best available outcome questionnaire and a set of thresholds. The final choice of the ACHE tool’s components will be carried out with the USER Group.Work package 3: We will assess the likely impact acceptability and feasibility of introducing the ACHE tool within the NHS using three different approaches. WP 3.1 We will assess the likely impact of using the ACHE tool on patients’ referral to secondary care by applying the ACHE tool to a series of 400 patients who have been referred to our Integrated Care and Treatment hub. We will demonstrate the impact of the ACHE tool by calculating the % of patients who would not have been referred if the ACHE tool had been applied in Primary Care.WP 3.2 We will use questionnaires to ask the opinion of a large number of GPs and patients regarding the proposed usage of the ACHE tool focusing on its content means of use and acceptability. WP 3.3 Finally we will use a broad stakeholder consultation group using deliberative methods of stakeholder engagement to further explore acceptability/feasibility. WP3 will deliver a consensus about use of the ACHE tool indentifying thresholds that are acceptable to stakeholders. Final Outcome: We will produce the ACHE tool for assessing patients with hip & knee arthritis that can be used in Primary Care to identify candidates for hip and knee joint replacement guiding referral to secondary care. The tool will be incorporated into the NHS patient pathway for hip and knee replacement surgery to standardise patient care reducing unwarranted variation and improving patient outcome. Use of the ACHE tool will be included within the NHS Commissioning Guidance for hip & knee


Research activity codes: 7.3 MANAGEMENT AND DECISION MAKING
Health categories: MUSCULOSKELETAL