title: Measuring pain in systemic sclerosis: comparison of the short-form McGill Pain Questionnaire versus a single-item measure of pain.
abstract: OBJECTIVE
  Studies of pain in systemic sclerosis (SSc) have used a variety of measures, including single-item measures and the 15-item short-form McGill Pain Questionnaire (MPQ-SF). The objective of our study was to compare the performance of the MPQ-SF to a single-item pain numerical rating scale (NRS) and determine whether the MPQ-SF effectively differentiates between sensory and affective components of pain in SSc.
  
  
  METHODS
  A cross-sectional, multicenter study of 1091 patients from the Canadian Scleroderma Research Group Registry who completed the MPQ-SF and pain NRS. Correlations of MPQ-SF total scores and pain NRS scores with relevant outcome measures (disability, quality of life, depressive symptoms) were compared. To assess whether the MPQ-SF differentiated between sensory and affective factors, confirmatory factor analysis modeling was used, and correlations of sensory and affective factor scores with other outcome measures were compared.
  
  
  RESULTS
  MPQ-SF total score and the pain NRS correlated similarly with other outcome measures, as did the sensory and affective scores. MPQ-SF sensory and affective factors were highly correlated (0.92), and a single-factor model fit as well as a 2-factor (sensory and affective) model.
  
  
  CONCLUSIONS
  The substantial overlap between sensory and affective subscales of the MPQ-SF and the similarity of the MPQ-SF and NRS pain measures compared to other patient-reported outcomes suggest that the 15-item MPQ-SF does not provide tangible advantages compared to the single-item pain NRS. These findings support recommendations to use a single-item NRS pain measure in SSc as it is less burdensome to patients than the MPQ-SF.
authors.affiliation: Department of Psychiatry, McGill University, Montréal, Québec, Canada.
authors.forename: Ghassan
authors.initials: G
authors.lastname: El-Baalbaki
authors.forename: Janie
authors.initials: J
authors.lastname: Lober
authors.forename: Marie
authors.initials: M
authors.lastname: Hudson
authors.forename: Murray
authors.initials: M
authors.lastname: Baron
authors.forename: Brett D
authors.initials: BD
authors.lastname: Thombs
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002170:Canada; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology / Q000503:physiopathology*; D010147:Pain Measurement / Q000592:standards*; D012042:Registries; D012595:Scleroderma, Systemic / Q000150:complications / Q000503:physiopathology*; D012720:Severity of Illness Index; D055815:Young Adult