Influence of comorbidity on self-assessment instrument scores of patients with idiopathic adhesive capsulitis

Background: The purpose of this study was to determine whether comorbid factors influence the results of self-assessment instruments completed by patients with idiopathic adhesive capsulitis of the shoulder. We hypothesized that an increased number of comorbidities would be correlated with greater pain and worse function as measured by general and shoulder-specific outcome tools. Methods: One hundred consecutive patients with phase-II adhesive capsulitis were prospectively evaluated with use of a general health questionnaire, a visual analog pain scale, the Simple Shoulder Test, the Disabilities of the Arm, Shoulder and Hand questionnaire, and the Short Form-36. There were seventy-one women and twenty-nine men, with a mean age of fifty-two years (range, thirty-six to eighty-two years). Comorbidities included medical factors (e.g., diabetes and heart disease) and social factors (e.g., tobacco use and pending litigation). Linear regression analysis was performed to determine correlations between the number of comorbidities and the results of the questionnaires. Results: Patients with more comorbidities had significantly lower scores on the Disabilities of the Arm, Shoulder and Hand Questionnaire (p = 0.0005) and the Short Form-36 subscale of physical function (p = 0.0009) as well as poorer scores on the Simple Shoulder Test and the Short Form-36 subscales of physical role, social function, emotional role, and mental health. Although there was no correlation between increased comorbidity and pain as measured on the visual analog scale, the comfort/pain subscale of the Short Form-36 showed a significant correlation with increased comorbidity (p = 0.004). Conclusions: Idiopathic adhesive capsulitis is a debilitating condition. Comorbid factors have a significant effect on the pain and dysfunction (as measured on shoulder-specific and general health instruments) experienced by patients with this disorder. These findings can be applied to the evaluation of these patients and may help to identify patients who potentially require a longer treatment course or those whose outcome will be less satisfactory.