title: Interconversion of three measures of performance status: an empirical analysis.
abstract: OBJECTIVE
  To construct empirically a conversion table to convert performance status scores among the Eastern Cooperative Oncology Group (ECOG), Karnofsky Performance Status (KPS) and Palliative Performance Scale (PPS) measures, using a large sample of patients with advanced cancer.
  
  
  METHODS
  Seven physicians completed assessments on 1385 consecutive patients attending an oncology palliative care clinic, or admitted to an acute cancer palliative care unit. The three measures were distributed as a questionnaire package; the order in which they were presented was randomly assigned for each week. Scales were compared using the hit rate and the weighted kappa coefficient (κ(w)). The KPS and PPS were compared directly; for comparisons of either scale with the ECOG, all 70 possible categorisations of KPS and PPS were computed. An 'ideal' categorisation was selected based on maximisation of both statistical methods.
  
  
  RESULTS
  The KPS and PPS matched in 1209 out of 1385 assessments (hit rate 87%; κ(w) 0.97). For both the KPS and the PPS, the categorisation of 100 (ECOG 0), 80-90 (1), 60-70 (2), 40-50 (3), 10-30 (4) had the highest hit rate (75%), and the second highest κ(w) (0.84, p<0.0001). One other combination had a slightly higher κ(w) (0.85 for both KPS and PPS), but a lower hit rate (73% for KPS, 72% for PPS).
  
  
  CONCLUSIONS
  We have derived empirically a conversion scale among the ECOG, KPS and PPS scales. The proposed scale provides a means of translating amongst these measures, which may improve accuracy of communication about performance status amongst oncology clinicians and researchers.
authors.affiliation: Department of Biostatistics, Ontario Cancer Institute, Princess Margaret Hospital, University Health Network, Toronto, Canada.
authors.forename: Clement
authors.initials: C
authors.lastname: Ma
authors.forename: Shazeen
authors.initials: S
authors.lastname: Bandukwala
authors.forename: Debika
authors.initials: D
authors.lastname: Burman
authors.forename: John
authors.initials: J
authors.lastname: Bryson
authors.forename: Dori
authors.initials: D
authors.lastname: Seccareccia
authors.forename: Subrata
authors.initials: S
authors.lastname: Banerjee
authors.forename: Jeff
authors.initials: J
authors.lastname: Myers
authors.forename: Gary
authors.initials: G
authors.lastname: Rodin
authors.forename: Deborah
authors.initials: D
authors.lastname: Dudgeon
authors.forename: Camilla
authors.initials: C
authors.lastname: Zimmermann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D017567:Karnofsky Performance Status / Q000592:standards; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000628:therapy*; D010166:Palliative Care / Q000379:methods*; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D055815:Young Adult