title: Deriving a Barthel Index from the Northwick Park Dependency Scale and the Functional Independence Measure: are they equivalent?
abstract: OBJECTIVE
  to examine the extent of agreement between Barthel Index scores derived from Northwick Park Dependency Scores (NPDS) and the Functional Independence Measure (FIM) ratings, in an inpatient setting.
  
  
  METHODS
  previously described conversion criteria were applied in a secondary analysis of a large existing dataset, gathered in a tertiary specialist inpatient neurorehabilitation unit.
  
  
  METHODS
  patients with neurological disabilities (N = 1347), mainly following acquired brain injury.
  
  
  METHODS
  comparison of Barthel scores derived from the NPDS (rated by nursing staff) and from parallel FIM scores (rated by the therapy team).
  
  
  RESULTS
  very strong intraclass correlations were observed between the total scores (0.93, P<0.001); 95% limits of agreement ranged from -3.53 to 4.90. Item-by-item agreement (linear-weighted Cohen's kappa coefficients) ranged from 0.41 to 0.77, which represents 'moderate' to 'substantial' agreement. A significant bias towards lower NPDS-derived scores (median 10 (interquartile range (IQR) 6-16) compared with median 11 (IQR 7-16) for the FIM-derived score; Wilcoxon z 11.60, P<0.001) was considered most likely to reflect actual differences in patient performance observed by therapy and nursing staff.
  
  
  CONCLUSIONS
  this study demonstrates good overall agreement between the Barthel Index ratings derived from NPDS and FIM scores. However, scores may be affected by differential performance with nursing and therapy staff, and should not automatically be regarded as equivalent.
authors: Kings College London, School of Medicine, Department of Palliative Care, Policy and Rehabilitation Regional Rehabilitation Unit, Northwick Park Hospital, London, UK. Lynne.turner-stokes@dial.pipex.com
authors: Lynne
authors: L
authors: Turner-Stokes
authors: Heather
authors: H
authors: Williams
authors: Hilary
authors: H
authors: Rose
authors: Sarah
authors: S
authors: Harris
authors: Diana
authors: D
authors: Jackson
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000368:Aged; D000465:Algorithms; D001930:Brain Injuries / Q000534:rehabilitation*; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020380:Needs Assessment; D011594:Psychometrics; D015203:Reproducibility of Results; D000071939:Stroke Rehabilitation; D006113:United Kingdom