Objective

DASH, SPADI and Constant scales are commonly used for clinical evaluation of patients suffering from degenerative rotator cuff disease (DRCD) of the shoulder. However, their psychometric properties have not yet been compared. This comparison could help to choose the most suitable evaluation tool. The objective of this work is therefore to compare the psychometric properties of DASH, SPADI and Constant scales in patients with DRCD.

Material/patients and methods

Patients with DRCD were prospectively included. Each of the scales (0–100) were applied twice with a one-week interval before and after physiotherapy. The perceived improvement after treatment was assessed using a numerical scale (0–4). The test-retest reliability of DASH, SPADI and Constant scales was assessed before treatment using the interclass correlation coefficient (ICC, very good reliability > 0.9). The responsiveness was assessed using paired t-test ( P < 0.05) and standardized mean difference (SMD, small: 0.2, moderate: 0.5 important: 0.8). The correlation between the percentage of variation and the score of improvement after treatment was also measured by the Spearman coefficient (moderate correlation > 0.35, high > 0.5, P < 0.05).

Results

Fifty-three patients were included: age 59 ± 11 years, ratio F/M 37/16, duration of pain 27 ± 55 months, DASH 46 ± 16, SPADI 48 ± 18, Constant 53 ± 16. The test-retest reliabilities for DASH (0.97), SPADI (0.95) and Constant (0.92) scales were considered as very good. The scores for the 3 scales were improved after physiotherapy ( P < 0.05). The SMD was moderate for DASH (0.56) and SPADI (0.72) scales, and small for Constant (0.44) scale. The correlation between the percentage of variation and perceived improvement after physiotherapy was found high for SPADI (0.59, P < 0.0001), moderate for DASH (0.42, P < 0.01), and not significant for Constant scale.

Discussion – conclusion

The test-retest reliability of respectively DASH, SPADI and Constant scales was found to be very good in patients suffering from DRCD. The highest responsiveness is achieved with SPADI scale, the lower with Constant. These results support the high recommendation for use of SPADI scale to assess patients with DRCD.