Title: Synthesising a clinical Prognostic Rule for Ankle INjuries in the Emergency Department (SPRAINED)
Funder: Department of Health (England)

Abstract: We will[1] Develop a multi-variable prognostic tool in an existing dataset (HTA funded Collaborative Ankle Support Trial (CAST). CAST is recent large (n=584) covered 8 EDs and has a near comprehensive set of predictors and outcomes.[2] Complete a review of prognostic factors for ankle sprains; engage clinical/user opinion and design a tool to complement existing clinical pathways[3] Complete an external validation study (n=675).Setting: 5 UK NHS EDsTarget population:Inclusion: Adults (>16 years of age) with an acute ankle sprain (<7 days old) who provide informed consent to participate.Exclusions: Ankle fracture (excluding flake fracture < 2mm). Other recent (<3 months) lower limb fracture.Outcome: Not recovered at 9 months defined as either severe or persistent chronic pain instability (including recurrent sprain) and/ or significant lack of confidence in the ankle.Health technologies being assessed: Development of a short prognostic tool. We intend that the tool measure will be easy to completeand acceptable to clinicians and patients. Ideally it will not require specialist training.Stage 1 - We will identify variables for the prognostic tool using multivariable logistic regression modelling of the CAST dataset. Candidate predictors include age sex sprain severity at ED attendance initial pain intensity previous injury ligament tests ability to weight bear amount of weight bearing and severity of presenting symptoms We will model the impact of a review at 5 days when tests can be easier to complete.Stage 2 - We will conduct a systematic review of risk factors using poor outcome to identify any additional measures that should be considered. We will consult with the clinical research and patient communities to finalise the content and design the layout of a tool and resolve issues arising. For example we may find improvement in prognostic accuracy with addition of measures at around 5 days but the implication is inconvenient re-attendance at hospital for patients.Stage 3 - We will recruit 675 people attending EDs. Depending on final format the patient or ED clinicians will be asked to complete the prognostic tool. The results of the tool would be withheld and computed after final follow up. A short questionnaire will be collected from participants at 5-7 days 4 and 9 months and will include severe and persistent symptoms the validated Foot and Ankle Outcome Score health service resource use during follow up and health related quality of life.Sample size for Stage 1 and 3: Sample size will follow the recommended 10 events-per-variable.In the CAST dataset the number of outcome events is 140 thus the model will be constrained to 15 predictors. For validation recommendations are a minimum of 100 outcome events. Based on CAST the event rate is between 26% and 32% requiring data on 313 to 385 people. Allowing for a lower event rate (with the inclusion of all sprains) and maximum loss to follow up of 25% the target validation sample size is 675 participants.Project timetables including recruitment rate: We propose a 30 month timetable. Stages 1 and 2 will be complete by Month 7. Stage 3 cohort study will be conducted between months 7 and 25. We will recruit 675 participants from 5 EDs from a pool of 7500 to 10000 ankle sprains per annum and a conservative 15 sprains per centre per month. Months 25-30 will be used for analysis reporting & dissemination.


Research activity codes: 7.3 MANAGEMENT AND DECISION MAKING
Health categories: INJURIES AND ACCIDENTS