Background/Purpose: Hand involvement is observed in almost all patients with Systemic Sclerosis (SSc), and is due in various proportions to skin and tendon fibrosis, arthritis and microvascular impairment, sometimes complicated with digital ulcers (DUs). The Duruoz’s Hand Index (DHI) (or Cochin hand functional disability scale), is a reliable tool for hand function assessment in diseases like rheumatoid arthritis and SSc. A short form of the DHI comprising of 6 items (DHI-6) has been recently developed and validated. The purpose of this study was to assess the reliability, validity and sensitivity to change of the new DHI-6 in a cohort of patients with SSc.

Methods: 70 consecutive patients with SSc, examined in our EUSTAR center, satisfying the 2013 ACR/EULAR classification criteria, were included. Patients completed the DHI, the Scleroderma Health Assessment Questionnaire (SHAQ) questionnaires and the Hand Mobility in Scleroderma (HAMIS) test. Three anthropometric measures to assess finger range of motion were also measured: the finger extension (FE), finger-to-palm distance (FTP) and Δ FTP (FE – FTP). Step 1: In 38 patients the test-retest reliability, using intra-class correlation coefficients (ICC), and the internal consistency (Cronbach’s alpha test) were examined. Step 2: In all 70 patients, the criterion validity by correlation coefficients with SHAQ, HAMIS and the anthropometric measures, and the discriminative capacity between different subsets of patients by Mann-Whitney U-test were examined. Moreover, the DHI-6 was correlated with DHI. Step 3: 35 consecutive patients had a second evaluation at an interval of (mean± SD) 8.1±30. months; among them, 8 patients had progressive early diffuse SSc. Sensitivity to change was assessed in these patients using the effect size (ES) (Cohen’s d) and the standardized response mean (SRM).

Results: The study included 63 females/7 males with SSc, age 50.9±13.0 years, disease duration 5.8±5.6 years; 27 with diffuse cutaneous SSc (dcSSc) and 43 with limited cutaneous SSc (lcSSc). The DHI-6 had a score of 6.7±6.5, range 0-25 (possible range 0-30) at baseline, and 8.3±7.0, range 0-24 at follow-up. The DHI-6 presented an excellent test-retest reliability (ICC 0.98), and a good internal consistency (Cronbach’s alpha 0.89). Criterion validity of the DHI-6 was proved by moderate to strong correlations with HAMIS, FE, FTP, Δ FTP and the SHAQ disability index (Spearman’s rho 0.48-0.82, p<001). Correlation of the DHI-6 with the DHI was excellent, with a Spearman’s rho of 0.96, p<0.001. The discriminative capacity of the DHI-6 was proven by statistically significant differences between patients with and without: synovitis, flexion contractures of the fingers, and history of DUs. The sensitivity to change (ES of 0.57 and SRM of 1.11) was very good for detecting a minimally important difference.

Conclusion: The simplified DHI is a brief, valid and reliable instrument for measuring hand disability in SSc. These results suggest that the DHI-6 could be used both in day-to-day practice and in clinical trials, reducing patient burden and increasing research capacity. However, more studies are needed to confirm these results.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/reliability-validity-and-sensitivity-to-change-of-the-simplified-duruoz-hand-index-in-systemic-sclerosis/