Oxford Shoulder Score (OSS)
The Oxford Shoulder Score (OSS) is a validated, shoulder specific patient-outcome reporting measure that was designed to assess the outcome of all shoulder surgeries (with the exception of instability surgery). It is now used in a number of countries (including the UK, Israel and Finland) and has also been applied in cohort studies, audits and national joint replacement registries.
The OSS questionnaire contains twelve items, each with five potential answers. Originally, patients were asked to rate their symptoms between 1 (minimal symptoms) and 5 (severe symptoms). The combined total gives a minimum score of twelve and a maximum score of sixty. However, counter-intuitively to many other PRO measures, higher scores in the OSS imply worse functionality while lower scores imply better functionality.
At the time of its development the OSS scoring system was designed to be as simple as possible in order to encourage its use. However, this scoring system was the exact opposite to its sister outcome measures – the Oxford Hip and Oxford Knee surveys, where higher scores corresponded to better outcomes. Subsequently, many surgeons using the Oxford Hip and Oxford Knee surveys found the scoring for the Oxford Shoulder unintuitive and resorted to using different systems.
In 2009, the authors of the OSS reversed the scoring methodology so that lower scores would represent worse outcomes, thus bringing it in line with similar measures. As a result, each of the twelve items are now scored from 4 (fewest symptoms) to 0 (worse/most severe symptoms) with total scores ranging from 48-0.
Users of the OSS measure should keep this in mind when reading medical research studies and make note if the study was conducted either pre-2009 or post-2009 when the scoring methodology was changed.
The OSS itself has undergone rigorous testing for validity, reliability, sensitivity to change and has been shown to be a robust measure for assessing the outcome of shoulder surgery. It is also helpful for looking at the success of an intervention by comparing pre-and post-operative scores.
Strengths
One of the perceived advantages of using a joint-specific score like the OSS is that it allows it to be sensitive to the disability from the shoulder while being influenced as little as possible by other comorbidities.
The Oxford Shoulder Questionnaire has been shown to correlate well with both the Constant Score and the SF-36 assessment. It has also been described as a valid measure of shoulder function in patients with rheumatic diseases who undergo shoulder surgery.
Considerations
The main disadvantage of the Oxford Shoulder Score is that it does not assess shoulder instability which limits its effectiveness as an overall measure of assessment. Therefore, the significant number of pathologies that are associated with shoulder instability are automatically excluded from use with this measure.
The Oxford Shoulder Score is a patient-friendly questionnaire and a valid and responsive measure that can be employed in surveys or clinical trials for shoulder surgery patient groups.
Licensing and Cost
The Oxford Shoulder Score requires a license, and for certain users it also requires a fee to utilize. To learn more about the Oxford Shoulder Score, visit their website: https://innovation.ox.ac.uk/outcome-measures/oxford-shoulder-score-oss/.
Sources
The range of the Oxford Shoulder Score in the asymptomatic population: a marker for post-operative improvement | The Oxford shoulder score revisited | Identification of shoulder-specific patient acceptable symptom state in patients with rheumatic diseases undergoing shoulder surgery
