Development and validation of a patient-reported outcome in systemic sclerosis: the Hand scleroDerma lived Experience (HAnDE) scale.

Abstract

Hand involvement in systemic sclerosis (SSc) is at the core of the disease, with a substantial impact on both functional aspects and quality of life. There is no patient-reported outcome (PRO) scale globally assessing hand involvement in SSc. To develop and validate a PRO scale, the Hand scleroDerma lived Experience (HAnDE) scale, to assess the lived experience of hand involvement in patients with SSc. This was an exploratory sequential mixed-methods study with two phases: (i) PRO development through an inductive process to analyse the structure of lived experience, involving 21 patients with SSc; and (ii) PRO validation by assessing the psychometric properties of the scale among 105 patients with SSc. Phase 1 enabled us to generate the 18-item provisional scale. From Phase 2, the mean (SD) total score of the scale was 29·16 (16·15). The item reduction process retained 16 items with five levels of answers (range 0-64). Internal consistency of the 16-item version was excellent (Cronbach's alpha = 0·946). Construct validity was very good, principal component analysis pointing towards a unidimensional instrument, with one factor explaining 56% of the variance, and concurrent validity being confirmed: Cochin Hand Function Scale r = 0·66; Health Assessment Questionnaire - Disability index r = 0·58; Hospital Anxiety and Depression Scale, anxiety r = 0·51, depression r = 0·4; Mouth Handicap in Systemic Sclerosis scale r = 0·61; 36-Item Short Form Health Survey, physical component r = -0·48, mental component r = -0·46; and Kapandji score r = -0·46. The correlations were statistically significant (P < 0·05). We propose, for future trials and clinical practice in SSc, a new PRO, the HAnDE scale, that assesses all the dimensions - functional, aesthetic, relational, existential and emotional - of the lived experience of hand involvement in SSc.