title: Measuring time input loss among patients with rheumatoid arthritis: validity and reliability of the Valuation of Lost Productivity questionnaire.
abstract: OBJECTIVE
  To examine the validity and test-retest reliability of the Valuation of Lost Productivity (VOLP) questionnaire among patients with rheumatoid arthritis (RA).
  
  
  METHODS
  Absenteeism, presenteeism, and unpaid work loss due to health were measured. Patients with RA who had paid work at their recent follow-up were recruited from the Early RA Network cohort. The VOLP was administered on two occasions.
  
  
  RESULTS
  A total of 152 patients were included in our analysis. The correlations between VOLP and function, pain, fatigue, and disease activity ranged 0.24 to 0.42. The correlations between VOLP and Work Productivity and Activity Impairment questionnaire were 0.57 for absenteeism, 0.42 for presenteeism, and 0.39 for unpaid work loss. The Kappa statistics were greater than 0.6 except for unpaid work loss.
  
  
  CONCLUSIONS
  This study provides evidence for the validity of the VOLP in measuring time input loss among people with RA.
authors.affiliation: Centre for Health Evaluation and Outcome Sciences, St Paul's Hospital, Vancouver, British Columbia, Canada.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Nick
authors.initials: N
authors.lastname: Bansback
authors.forename: Jacek
authors.initials: J
authors.lastname: Kopec
authors.forename: Aslam H
authors.initials: AH
authors.lastname: Anis
mesh_terms: D000041:Absenteeism; D001172:Arthritis, Rheumatoid / Q000191:economics*; D004526:Efficiency; D006801:Humans; D008875:Middle Aged; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires