Title: Treatment of first-time traumatic anterior shoulder dislocation UK.TASH-D Study
Funder: Department of Health and Social Care

Abstract: AIM: To study the association between surgical treatment (compared to no surgery) and re-dislocation rates following first time anterior shoulder dislocation (TASD) in young adults and to also identify predictors of re-dislocation. This requires 2 Work Packages (WP). WP1 will test the internal and external validity of the Clinical Practice Research Datalink (CRPD) in identifying TASD. WP2 is a matched cohort analysis of a CPRD and Hospital Episode Statistics (HES) linked dataset. SETTING: Two large rountinely collected NHS datasets; the CPRD will be used to identify patients with TASD and cohorts linked to HES for shoulder stabilisation procedures POPULATION: 10,449 patients aged 16-35 years in CPRD with TASD and two years follow up. WP1 DESIGN: Internal and external validation of shoulder dislocation coding and treatments within a routinely collected dataset (CPRD). WP2 DESIGN: Propensity score-matched cohort study using linked CPRD and HES. All events and outcomes will be collected using a pre-agreed list of READ CODES (CPRD) and OPCS 4.7 CODES (HES). INCLUSION CRITERIA: Patients aged 16-35 yrs with first time TASD who can be linked by CPRD-HES with a minimum two year follow up in CPRD. EXCLUSION CRITERIA: Surgery after more than one TASD; instability treated with rotator cuff or fracture surgery. INTERVENTION: Early surgical repair in this NHS waiting list context is ‘decision to treat surgically after first TASD with surgery occurring within 6 months’. CONTROL: If WP1 reveals free text and referral codes for physiotherapy are lacking, conservative care will be ‘non surgical intervention after first TASD’. OUTCOMES: Primary outcome is re-dislocation rate, identified by further re-dislocation code entries in CPRD for 2 years after the first surgery date (Surgical Group) or after the first dislocation code (Non-Surgical Group) SAMPLE SIZE: Using a 2-sided log rank test for equality of survival curves, 90% power, 5% level of significance (alpha), where outcome is time to re-dislocation, with an anticipated 25% re-dislocation rate in the non-surgical control group compared to a 20% re-dislocation rate in the surgical group [2] (equivalent to a hazard ratio of 0.78) and assuming a 10% loss to follow up and equal group sizes, we require a total sample size of 3065 with 656 expected total number of re-dislocations. There are 10,449 such patients in CPRD [7] STATISTICAL ANALYSIS: For Surgical v Non-surgical intervention on re-dislocation rates; advanced statistical techniques [1-3,8,9] including propensity scores, Cox regression modelling and Rosenbaum bounds sensitivity analysis will be used to avoid the inherent confounders and immortal time bias present in observational studies. For predictors of recurrent dislocations; the CPRD-HES linked dataset will be used to develop a model to identify patients at risk of subsequent re-dislocation using multiple imputation methods [10,11], survival models (Cox regression) and fractional polynomials. Internal validation will be tested by a combination of multiple imputation and bootstrapping [12-14] EXPERTISE: CPRD/HES (DPA,AJ,NKA,SH,GC,TH); data analysis & interpretation (AJ,DPA,NKA,CG,TH,AR,SH,SL,JLR); Epidemiology (DPA,AJ,GC,NKA); PPI (JLR,AR,Pat Rep)

Lay abstract: Traumatic anterior shoulder dislocation (TASD) is when the humeral head (top end of the arm bone at the shoulder) is forced out of the shoulder socket frontwards. This can happen after sport injuries or falls and is most common in younger patients. The injury is very painful and the shoulder often stays dislocated until it is ‘reduced’ or ‘put back’ in hospital. This type of injury often causes the joint to remain ‘unstable’ and more dislocations can occur. In some people these dislocations are very frequent and can even occur during sleep. The two main ways of treating this problem are physiotherapy and surgery. Traditionally physiotherapy has been used first and surgery used if the physio does not work. However, in recent years patients are more frequently being treated with surgery as the risk or further dislocation without surgery is considered to be high. While surgical treatment has become more common, researchers and doctors still don’t know which patients are best treated with physiotherapy and which patients are best treated first with surgery. Because dislocations cause so much pain, stress and disability, it is important to know if surgery after one dislocation is worthwhile in preventing further problems. Rather than run a clinical trial involving patients, we have an opportunity to answer this question using information that is already available within the NHS. GP’s record all patient problems on a computerised system called CPRD. We know there are around 26,534 patients with shoulder dislocations in the database, and at least 10,449 of these will be young patients aged 16-35 years [7] with TASD. This large number of shoulder dislocation records means we can answer this commissioned research question using analysis of this database. We will also need to use a Hospital database that contains information on the patients that have had operations. This hospital database is called HES and it records the type of operations that patients have had such as shoulder surgery for dislocations. We therefore plan a study to link these two large computer record systems to see which patients had surgery and which did not and to assess which patients had further dislocations. To do this we have put together a research team with expertise in shoulder dislocation and expertise in studying these two databases. The team has used this method of database analysis before including the advanced statistical methods that need to be used. To further ensure this database can be successfully used for this purpose, we plan to first test the coding of shoulder dislocations in the CPRD database by performing an initial ‘validation (or testing) study’ for 9 months. If this is successful it means we have a high chance of then answering the research question with a full analysis of the linked CPRD and HES databases which will take another 18 months. During this anlaysis we will also identify any predictors of re-dislocation such as occupation or sport that may influence the need for surgery. On completion of this study we plan to publicise our results widely and use the evidence to influence and improve patient pathways and guidelines for primary care and hospital health workers who manage and treat patients with first time traumatic anterior shoulder dislocation.

Research activity codes: 6.4 SURGERY
Health categories: MUSCULOSKELETAL