Background: Disease-specific Quality Of Life (QOL) measures are devised to assess the impact of a specific disease across a spectrum of important domains of life. The purpose of this study was to examine the cross-sectional and longitudinal construct validity (sensitivity to change) of two rotator cuff diseasespecific measures, the Rotator Cuff-Quality Of Life (RC-QOL) and the Western Ontario Rotator Cuff (WORC) index, in relation to one another and to other joint and limb specific measures in the same population of the patients suffering from rotator cuff pathology.

The patient-report component of the CMS measures a multidimensional concept. The strength component had moderate correlations with isometric strength measures of the shoulder external rotators and abductors. The total CMS appears to measure a construct that is not totally captured by competing measures. The unexplained variance may be due, in part, to the lack of importance of the patient's physical impairment to symptoms or activity limitations as measured by other instruments.