The Oxford Shoulder Instability Score (OSIS)

The Oxford Shoulder Instability Score (OSIS) is a short, 12-item, condition-specific, patient reported outcome (PRO) measure developed and validated for measuring surgical and non-surgical therapeutic outcomes of patients presenting with unidirectional or multi-directional instability of the shoulder.

Background

The OSIS is short, practical, reliable, valid and sensitive to changes of clinical importance.

Some of the attributes of the OSIS are:

Short

The OSIS is a 12 item uncomplicated questionnaire. It therefore benefits from high completion rates. The OSIS is easy to deploy across diverse healthcare applications.

Reliable

Published results (see development paper) on patient groups demonstrate the reproducibility and internal consistency of the score.

Valid

The OSIS has been shown to correlate well with existing related clinical and generic PRO measures.

Sensitive to change

Effect size for the OSIS is large and results (see development paper) clearly show it outperforms generic PROs, including those with a physical role dimension.

Practical

Easy to complete and can be given to the patient at clinic or sent by post.

The PRO

The OSIS is a patient self-completion PRO measure containing 12 questions on activities of daily living particularly relevant to patients exhibiting shoulder instability. The OSIS has been specifically designed to assess outcome of therapy (both surgical and non-surgical) by measuring activities of daily living and pain of patients exhibiting shoulder instability.

Scoring System:

Details of the scoring system for the OKS can be downloaded in Dossier Extracts section

Development:

During the development of the Oxford Shoulder Score it became clear that patients presenting with persistent dislocation or subluxation of the shoulder were a distinct group whose condition was usually characterised by anticipation of problems arising in relation to specific activities rather than pain. This group required a specific outcome measure of its own, which led to the development of the OSIS.

The OSIS was developed using a multi-stage process, consistent with industry best-practice methods. The OSIS joins a portfolio of well-regarded and widely used orthopaedic PRO measures created by Dr Jill Dawson at the Health Services Research Unit (HSRU) in association with colleagues at the Nuffield Department of Population Health and the Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS) at the University of Oxford. The development of the OSIS was supported by world-leading clinicians at the NDORMS led by Professor Andrew Carr. Professor Carr was elected a fellow of the Academy of Medical Sciences in 2009 and is President elect of the British Elbow and Shoulder Surgery Society.

The items in the OSIS were derived from exploratory interviews rather than from clinical assumptions. Draft versions were tested on patients and the final content only agreed when patients understood it and felt no important items had been omitted. Subsequent testing of the OSIS was conducted on 92 patients exhibiting problems related to instability of the shoulder. Test results from the study of the 92 patients show the OSIS to be reliable, valid and sensitive to change.

Details of the development and validation of the OSIS are described in:

Dawson J, Fitzpatrick R, Carr A. The assessment of shoulder instability. The development and validation of a questionnaire. J Bone Joint Surg Br. 1998 Jan;81-B:420-6

The intraclass correlation has been calculated as 0.90 (95% C.I. 0.74, 0.96) (Moser, 2008). Moser,J.S., Barker,K.L., Doll,H.A., Carr,A.J. (2008) Comparison of two patient-based outcome measures for shoulder instability after nonoperative treatment. Journal of Shoulder and Elbow Surgery; 17 (6): 886-892

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