title: Measuring disability with parsimony: evidence for the utility of a single item.
abstract: OBJECTIVE
  To provide evidence for the utility of a single item measure designed to quantify disability in the past 30 days.
  
  
  METHODS
  Australian data from studies comprising a community-dwelling elderly sample (N = 328) and a sample of chronic osteoarthritis (OA) patients (N = 119) are reported. Degree of disability was classified as 0-30 days, 0 vs. 1 or more days, and 0-9 vs. 10 or more days. Associations between disability and a range of demographic, health-related, and psychological variables were assessed.
  
  
  RESULTS
  Participants with OA reported a significantly higher level of disability than participants from the community sample regardless of how disability was classified. Modest levels of association were noted between the number of disability days (0-30) and both health and psychological indices in both samples. The three alternative classifications of disability made little difference to the significance of associations. On balance, the comparison of 0-9 vs. 10 or more days appeared the more predictive classification of disability.
  
  
  CONCLUSIONS
  The performance of the single item measure of disability was generally very satisfactory. Future investigations into the clinical application of the item across a range of patient groups are encouraged.
authors.affiliation: Department of Rehabilitation and Aged Care, Flinders University, Adelaide, Australia.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Clark
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: Bond
authors.forename: Kirsty N
authors.initials: KN
authors.lastname: Prior
authors.forename: Amy C
authors.initials: AC
authors.lastname: Cotton
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D002908:Chronic Disease; D004185:Disability Evaluation; D006233:Persons with Disabilities / Q000534:rehabilitation; D005260:Female; D006305:Health Status Indicators; D006306:Health Surveys; D006801:Humans; D008297:Male; D010003:Osteoarthritis / Q000534:rehabilitation*; D011795:Surveys and Questionnaires