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Table 2 HDISS-DU score: construct validity

From: Psychometric validation of the Hand Disability in Systemic Sclerosis-Digital Ulcers (HDISS-DU®) patient-reported outcome instrument

MeasureValidity assessedSpearman’s rho
BaselineWeek 8Week 16
Number of DUsConvergent0.010.10*0.19**
SHAQ HAQ-DI grip domain scoreConvergent0.66***0.71***0.72***
SHAQ HAQ-DI hygiene domain scoreConvergent0.60***0.64***0.63***
SHAQ HAQ-DI eating domain scoreConvergent0.73***0.77***0.76***
SHAQ-DI dressing and grooming domain scoreConvergent0.69***0.73***0.73***
SHAQ VAS DU severity item scoreConvergent0.60***0.60***0.61***
Patient-reported severityConvergent0.57***0.62***0.64***
Physician-reported severityConvergent0.39***0.37***0.43***
WPAI:DU activity impairmentConvergent0.63***0.65***0.72***
Global pain scale item scoreConvergent0.55***0.61***0.65***
SHAQ HAQ-DI arising domain scoreDiscriminant0.39***0.50***0.50***
SHAQ HAQ-DI walking domain scoreDiscriminant0.34***0.47***0.40***
SHAQ HAQ-DI reach domain scoreDiscriminant0.56***0.67***0.63***
SHAQ VAS intestinal problems item scoreDiscriminant0.23***0.35***0.33***
SHAQ VAS breathing problems item scoreDiscriminant0.30***0.39***0.42***
WPAI:DU absenteeismDiscriminant0.24*0.26**0.31**
WPAI:DU presenteeismDiscriminant0.45***0.55***0.69**
WPAI:DU overall work impairmentDiscriminant0.45***0.52***0.66***
  1. Spearman’s rank-order correlation assessed the association between the HDISS-DU score and other measures at baseline, week 8 and week 16. A priori hypotheses identified measures expected to capture similar concepts (assessed for convergent validity) and different concepts (assessed for discriminant validity) to the HDISS-DU score
  2. *p < 0.05; **p < 0.01; ***p < 0.001
  3. DU digital ulcer, HAQ-DI Health Assessment Questionnaire Disability Index, HDISS-DU Hand Disability in Systemic Sclerosis-Digital Ulcers, SHAQ Scleroderma Health Assessment Questionnaire, VAS visual analogue scale, WPAI:DU Work Productivity and Activity Impairment Questionnaire: Digital Ulcer