Shoulder Outcome Measures

Abstract

Background Several shoulder function scores are used in research, with no universally adopted standard. This study compares 6 shoulder outcome scales. Hypothesis Correlations exist between shoulder outcome scales, allowing conversion between scales. Shoulder scales are correlated with age. Study Design Regression and correlation study. Methods Seventy subjects with shoulder pain completed 6 shoulder outcome scales. Pearson correlations were calculated between the total scores of the 6 instruments, between the components of the scales, and with age. Regression equations were calculated between scales. Results The range of r values for total scores was 0.495 [.lessequal] r [.lessequal] 0.770, P [.lessequal] .01. In general, a scale's components were themselves highly correlated and added little new information to the scale (0.260 [.lessequal] r [.lessequal] 0.705, P [.lessequal] .05). Most of the scale scores were highly correlated with age (0.291 [.lessequal] r [.lessequal] 0.582, P [.lessequal] .05). Constant's reported corrections for age reduced (from r = -0.582 to r = -0.250, P < .05) but did not eliminate age as a confounding variable. Conclusions Correlations exist between shoulder outcome scales, but existing shoulder scales are not equivalent in their assessments of function; they contain redundant information and, in some cases, may reflect a patient's age better than his/her shoulder function. The utility of conversion equations is minimized as a result of low to moderate correlations between scales.