title: Validity, reliability, and feasibility of durometer measurements of scleroderma skin disease in a multicenter treatment trial.
abstract: OBJECTIVE
  To determine the validity, reliability, and feasibility of durometer measurements of skin hardness as an outcome measure in clinical trials of scleroderma.
  
  
  METHODS
  Skin hardness was measured during a multicenter treatment trial for scleroderma using handheld digital durometers with a continuous scale. Skin thickness was measured by modified Rodnan skin score (MRSS). Other outcome data collected included the Scleroderma Health Assessment Questionnaire. In a reliability exercise in advance of the trial, 9 investigators examined the same 5 scleroderma patients by MRSS and durometry.
  
  
  RESULTS
  Forty-three patients with early diffuse cutaneous systemic sclerosis were studied at 11 international centers (mean age 49 years [range 24-76], median disease duration 6.4 months [range 0.3-23], and median baseline MRSS 22 [range 11-38]). The reliability of durometer measurements was excellent, with high interobserver intraclass correlation coefficients (ICCs) (0.82-0.92), and each result was greater than the corresponding skin site ICCs for MRSS (0.54-0.85). Baseline durometer scores correlated well with MRSS (r = 0.69, P < 0.0001), patient self-assessments of skin disease (r = 0.69, P < 0.0001), and Health Assessment Questionnaire (HAQ) disability scores (r = 0.34, P = 0.03). Change in durometer scores correlated with change in MRSS (r = 0.70, P < 0.0001), change in patient self-assessments of skin disease (r = 0.52, P = 0.003), and change in HAQ disability scores (r = 0.42, P = 0.017). The effect size was greater for durometry than for MRSS or patient self-assessment.
  
  
  CONCLUSIONS
  Durometer measurements of skin hardness in patients with scleroderma are reliable, simple, accurate, demonstrate good sensitivity to change compared with traditional skin scoring, and reflect patients' self-assessments of their disease. Durometer measurements are valid, objective, and scalable, and should be considered for use as a complementary outcome measure to skin scoring in clinical trials of scleroderma.
authors.affiliation: Boston University School of Medicine, Boston, MA 02118, USA. pmerkel@bu.edu
authors.forename: Peter A
authors.initials: PA
authors.lastname: Merkel
authors.forename: Nancy P
authors.initials: NP
authors.lastname: Silliman
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Denton
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Furst
authors.forename: Dinesh
authors.initials: D
authors.lastname: Khanna
authors.forename: Paul
authors.initials: P
authors.lastname: Emery
authors.forename: Vivien M
authors.initials: VM
authors.lastname: Hsu
authors.forename: James B
authors.initials: JB
authors.lastname: Streisand
authors.forename: Richard P
authors.initials: RP
authors.lastname: Polisson
authors.forename: Anita
authors.initials: A
authors.lastname: Akesson
authors.forename: John
authors.initials: J
authors.lastname: Coppock
authors.forename: Frank
authors.initials: F
authors.lastname: van den Hoogen
authors.forename: Ariane
authors.initials: A
authors.lastname: Herrick
authors.forename: Maureen D
authors.initials: MD
authors.lastname: Mayes
authors.forename: Douglas
authors.initials: D
authors.lastname: Veale
authors.forename: James R
authors.initials: JR
authors.lastname: Seibold
authors.forename: Carol M
authors.initials: CM
authors.lastname: Black
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Korn
mesh_terms: D000328:Adult; D000368:Aged; D004311:Double-Blind Method; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012595:Scleroderma, Systemic / Q000473:pathology*; D012680:Sensitivity and Specificity; D012867:Skin / Q000473:pathology*; D012885:Skinfold Thickness; D011795:Surveys and Questionnaires