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  • Development and prospective external validation of a tool to predict poor recovery at 9 months after acute ankle sprain in UK emergency departments: the SPRAINED prognostic model

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Rehabilitation medicine
Research
Development and prospective external validation of a tool to predict poor recovery at 9 months after acute ankle sprain in UK emergency departments: the SPRAINED prognostic model
  1. Michael M Schlussel1,
  2. David J Keene2,
  3. Gary S Collins1,
  4. Jennifer Bostock3,
  5. Christopher Byrne4,
  6. Steve Goodacre5,
  7. Stephen Gwilym6,
  8. Daryl A Hagan2,
  9. Kirstie Haywood7,
  10. Jacqueline Thompson2,
  11. Mark A Williams8,
  12. Sarah E Lamb1,2
  13. for the SPRAINED study team
    1. 1 Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
    2. 2 Centre for Rehabilitation Research, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
    3. 3 Patient and Public Involvement, Quality and Outcomes of Person-Centred Care Policy Research Unit, Canterbury, UK
    4. 4 Faculty of Health and Human Sciences, University of Plymouth, Plymouth, UK
    5. 5 School of Health and Related Research, University of Sheffield, Sheffield, UK
    6. 6 Oxford Trauma, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
    7. 7 Warwick Research in Nursing, Division of Health Sciences, Warwick Medical School, University of Warwick, Coventry, UK
    8. 8 Department of Sport, Health Sciences and Social Work, Oxford Brookes University, Oxford, UK
    1. Correspondence to Dr Michael M Schlussel; michael.schlussel{at}csm.ox.ac.uk

    Abstract

    Objectives To develop and externally validate a prognostic model for poor recovery after ankle sprain.

    Setting and participants Model development used secondary data analysis of 584 participants from a UK multicentre randomised clinical trial. External validation used data from 682 participants recruited in 10 UK emergency departments for a prospective observational cohort.

    Outcome and analysis Poor recovery was defined as presence of pain, functional difficulty or lack of confidence in the ankle at 9 months after injury. Twenty-three baseline candidate predictors were included together in a multivariable logistic regression model to identify the best predictors of poor recovery. Relationships between continuous variables and the outcome were modelled using fractional polynomials. Regression parameters were combined over 50 imputed data sets using Rubin’s rule. To minimise overfitting, regression coefficients were multiplied by a heuristic shrinkage factor and the intercept re-estimated. Incremental value of candidate predictors assessed at 4 weeks after injury was explored using decision curve analysis and the baseline model updated. The final models included predictors selected based on the Akaike information criterion (p<0.157). Model performance was assessed by calibration and discrimination.

    Results Outcome rate was lower in the development (6.7%) than in the external validation data set (19.9%). Mean age (29.9 and 33.6 years), body mass index (BMI; 26.3 and 27.1 kg/m2), pain when resting (37.8 and 38.5 points) or bearing weight on the ankle (75.4 and 71.3 points) were similar in both data sets. Age, BMI, pain when resting, pain bearing weight, ability to bear weight, days from injury until assessment and injury recurrence were the selected predictors. The baseline model had fair discriminatory ability (C-statistic 0.72; 95% CI 0.66 to 0.79) but poor calibration. The updated model presented better discrimination (C-statistic 0.78; 95% CI 0.72 to 0.84), but equivalent calibration.

    Conclusions The models include predictors easy to assess clinically and show benefit when compared with not using any model.

    Trial registration number ISRCTN12726986; Results.

    • prognosis
    • clinical prediction rule
    • logistic model
    • ankle injuries
    • sprains and strains

    This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See: https://creativecommons.org/licenses/by/4.0/.

    https://doi.org/10.1136/bmjopen-2018-022802

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      Footnotes

      • Contributors MMS analysed and interpreted the data, and led the writing of the manuscript. DJK had substantial contribution in data acquisition, analysis and interpretation. GSC had substantial contribution in the study conception and design, data analysis and interpretation. JB, SG and KH had substantial contribution in the study conception and design. CB, DAH and JT had substantial contribution in the data acquisition. MAW had substantial contribution in the study conception and design and data acquisition. SEL was responsible for the study conception and design, and had substantial contribution in data interpretation. All authors revised and approved the final version of the manuscript.

      • Funding The SPRAINED study was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme (project number 13/19/06). Supported by the NIHR Biomedical Research Centre, Oxford, and the NIHR Fellowship programme (DJK, PDF-2016-09-056). SEL receives funding from the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care Oxford at Oxford Health NHS Foundation Trust.

      • Disclaimer The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the Health Technology Assessment programme, NIHR, NHS or the Department of Health and Social Care.

      • Competing interests None declared.

      • Patient consent Obtained.

      • Ethics approval Ethics approval was from the National Research Ethics Committee (REC) (London–Chelsea), REC number 15/LO/0538, on 10 April 2015. The study protocol was registered on 30 April 2015 (registry number ISRCTN12726986).

      • Provenance and peer review Not commissioned; externally peer reviewed.

      • Data sharing statement All data requests should be submitted to the corresponding author for consideration. Access to anonymised data may be granted following review. Exclusive use will be retained until the publication of major outputs.

      • Collaborators The SPRAINED study team members are: SEL (chief investigator); DJK (study lead); GSC, MAW, SG, Matthew Cooke, SG, Phil Hormbrey, David Wilson, JB (coinvestigators); DAH (study administrator); Damian Haywood (senior study manager); JT, CB (research physiotherapists); MMS (study statistician); Philip Hormbrey, Susan Dorrian, SG, Victoria Stacey, Tim Coats, Sarah Wilson, Jason Kendall, David Clarke, Antoanela Colda, Deborah Mayne (principal investigators and their clinical and research teams at collaborating recruitment centres); KH (consultation and senior facilitation of the consensus meeting).