What do the OMERACT Shoulder Core Set candidate instruments measure? An analysis using the refined ICF linking rules

Objective to assess the content and measurement constructs of the candidate instruments for the domains of ‘Pain’ and ‘Physical function/activity’ in the OMERACT Shoulder Core Set. The results of this ICF based analysis may inform further decisions on which instruments finally to be included in the Core Set.

Methods The materials for the analysis were the 13 candidate measurement instruments within ‘Pain’ and ‘Physical function/activity’ in the Shoulder Core Domain Set, which either passed or received amber ratings (meaning there were some issues with the instrument) in the OMERACT filtering process. The content of the candidate instruments was extracted and linked to the International Classification of Functioning, Disability and Health (ICF), using the refined linking rules. The linking rules enhance the comparability of instruments, by providing a comprehensive overview of the content of the instruments, the context in which the measurements take place, the perspectives adopted and the types of response options.

Results The ICF content analysis showed large variation in content and measurement constructs in the candidate instruments for the Shoulder Core Outcome Measurement Set.

Conclusion Two of six ‘Pain’ instruments include other constructs than pain. Within ‘Physical function/activity’ two candidate instruments matched the domain, three included additional content and the two last instruments included meaningful concepts in the response options, suggesting that they should be omitted as candidate instruments. The analyses show that the content in most existing instruments of shoulder pain and functioning extend across Core Set domains.