Reliability and Validity of the Avoidance of Daily Activities Photo Scale for Patients With Shoulder Pain (ADAP Shoulder Scale)

Abstract

Abstract Objective The Avoidance of Daily Activities Photo Scale for Patients With Shoulder Pain (ADAP Shoulder Scale) was developed to assess pain-related avoidance behavior during daily activities in people with shoulder pain. However, its measurement properties must be verified according to international guidelines. As such, this study investigated the following 4 measurement properties of the ADAP Shoulder Scale: reliability, measurement errors, convergent validity, and floor and ceiling effects. Methods The sample comprised 100 individuals with chronic shoulder pain (43 men and 57 women; mean duration of symptoms of 29.7 [SD = 89.0] months; mean age of 44.9 [SD = 15.9] years). The mean test–retest reliability range was 5 days via the intraclass correlation coefficient (ICC). Measurement errors included the standard error of measurement and the minimal detectable change. Convergent validity was analyzed by applying the Pearson correlation with the Tampa Scale for Kinesiophobia, Pain Catastrophizing Scale, and Shoulder Pain and Disability Index. Results The ADAP Shoulder Scale showed excellent test–retest reliability, both in all domains and in the total score [ICC(2,1) = 0.94; 95% CI = 0.92–0.96]. The standard errors of measurement for the free-movement, high-effort, and self-care domains were 8.1%, 6.0%, and 7.6%, respectively. The minimal detectable change for the total score of the ADAP Shoulder Scale was 16.0%. The total score of the ADAP Shoulder Scale was low to moderately correlated with the total scores of the Tampa Scale for Kinesiophobia (r = 0.52), Pain Catastrophizing Scale (r = 0.30), and Shoulder Pain and Disability Index (r = 0.72). No floor or ceiling effects were detected in the total score. Conclusion The ADAP Shoulder Scale is a reliable, valid instrument for assessing avoidance behavior in adults who have chronic shoulder pain and are not athletes. Impact This study provides evidence that the ADAP Shoulder Scale is appropriate for clinical and practical use in people with chronic shoulder pain.