Title: Evaluation of an aid to diagnosis for congenital dysplasia of the hip in general practice: controlled trial randomised by practice
Funder: Department of Health and Social Care

Abstract: Background: In the UK, a compulsory 6-week hip check is performed in primary care for the detection of developmental dysplasia of the hip (DDH). However, missed diagnoses and infants incorrectly labelled with DDH remain an important problem, potentially leading to adverse consequences for infants, their families and the NHS. National policy states that infants should be referred to hospital if the 6-week check &ldquo;suggests DDH&rdquo;, though there is no available tool to aid examination or offer guidelines for referral. We developed standardised diagnostic criteria for DDH, based on international Delphi consensus, and a 9-item Checklist that has the potential to enable non-experts to diagnose DDH in a manner approaching that of experts. Aims: 1. To elicit the influencing factors leading to inadequate diagnoses of DDH in primary care according to the Behaviour Change Wheel Framework. 2. To refine existing consensus-based standardised diagnostic criteria for DDH into a diagnostic aid tailored specifically for the 6-week check. 3. To determine if complementing the 6-week check with this aid is cost effective and reduces the number of mis-diagnoses. 4. To assess context, mechanism and implementation of the aid, and understand how the aid becomes embedded in practice. Setting: Primary care; GP practices and 15 Clinical Research Networks in England, with follow-up in secondary care. Participants: Primary care clinicians conducting 6-week infant hip checks and parents/carers of infants. Design: Mixed-method design for evaluation of complex interventions, conducted in three sequential phases, which will include qualitative and behaviour change studies; decision analysis; feasibility study and controlled trial randomised by practice with 2-year follow-up including clinical, health economic and qualitative process evaluation. Methods: First (10 months) In order to develop the most effective format, delivery mode and implementation strategy for an optimal diagnostic aid, we will undertake a rapid qualitative scoping study to determine the range of current organisational practices and explore the views of health professionals/parents about the 6-week hip check by interviewing primary care clinicians and carers from a purposive sample of practices in England, and shadowing them through the process of the 6-week check. We will use decision analysis to model the use of this aid in general practice. These studies will elicit potential barriers to appropriate diagnosis and referrals (primary behaviour for change), which we will evaluate within a Behaviour Change Framework (health professional s capability, opportunity and motivation). In parallel, we will draw on normalization process theory to elicit factors related to the embedding of the intervention in practice. This work will inform all aspects of the intervention and trial design. Second (8 months) We will test the feasibility of the intervention in a study of 6 established GP practices in North London. Findings of this pilot will refine the intervention where needed, and finalise all endpoints of the trial. Third (48 months) Over 16 months, we will recruit 152 GP practices in England to be randomly allocated to intervention or standard care when performing the 6-week check. We aim to detect a reduction, on average, from 3 to 2 referrals per practice as a consequence of primary care professionals using the aid. We hypothesise the intervention will lead to more accurate diagnoses and decisions at the 6-week check, i.e. fewer unnecessary referrals (measured in behavioural terms &ndash; i.e. number of appropriate referrals ) and fewer false negative diagnoses (measured as a non-behaviour &ndash; i.e. lack of referral for those needing it). While it is unfeasible to blind clinicians to interventions, an independent researcher will collect all outcomes (blinded to treatment) in secondary care for those referred at the 6-week check. In order to capture all false negatives, we will follow up all infants for two years. These data will be collected using deterministic data linkage blinded to interventions. We will compare the practices using Poisson mixed models, with the number of clinically insignificant (and significant) referrals from each practice as response variables. We will determine secondary outcomes at infant, carer and clinician levels and process outcomes, including fidelity, clinician and carer concerns and satisfaction with the intervention. To understand the economic impact of the intervention nationally, we will collect costs within the trial. This will allow a within-trial cost-effectiveness analysis, a cost-benefit analysis and a budget impact study. Using questionnaires, practice observation and interviews, we will explore the implementation, receipt and impact of the aid on clinicians and carers in order to understand how the intervention is embedded (or not) in practice (including variation across settings); help understand mechanisms of effect (including differences across sub-groups), and to identify key issues to consider for future implementation across the NHS.

Lay abstract: Developmental dysplasia of the hip (DDH) is a condition where the 'ball and socket' joint of the hips doesn't properly form in babies and young children. It's sometimes known as congenital hip dislocation or hip dysplasia. If DDH is detected by the age of 8 weeks, it can be treated fairly easily with a splint that is applied around the child s nappies and keeps the hips in the correct position. The success with such splint treatment is 85%. Babies hips are examined when they are born, and again 6-8 weeks later by their GP. Despite both of these checks, 1-2 in 1000 children are still diagnosed late with DDH. At that point, splinting is no longer successful. Instead, an operation is required, which puts those babies at a higher risk for early hip replacement in adult life. More than 2000 hip replacements are performed every year in Britain because of DDH. It is thus important to recognize DDH early. However, wrongly assuming a baby has DDH when the hips are normal can also be harmful. Such babies will get referred to hospital to receive tests. Sometimes even treatment will be given when it is actually not needed. This all leads to unnecessary worrying and costs. It is not well understood why there is confusion over whether a baby has DDH. Research suggests it is related to the doctor s knowledge, their skills, and the way the hip check is conducted. Our study will find out if we can reduce the confusion over whether a baby has (or has not) DDH. We will compare if GPs who use a checklist that we have developed will do better in identifying babies with DDH than those who do not use our checklist. In this research we will first modify our checklist for best use by GPs. We will conduct interviews with GPs to find out what the checklist should look like to be useful to them. We will find out whether there are any particular difficulties in properly picking up DDH in babies &ndash; our checklist could help overcome these difficulties. In the second part of the research we will divide GP practices in England into two groups. One group will use our checklist for all hip checks they carry out. The other group will work as they usually do, without the aid. We think that using our checklist will reduce the number of babies diagnosed well after 8 weeks with DDH. It will also reduce the number of babies that are wrongly assumed to have DDH and referred to hospital. We will also evaluate whether using the checklist reduces costs for families around trips to doctors or hospitals, and costs to the NHS.

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