title: Impact of co-morbidities on measuring indirect utility by the Medical Outcomes Study Short Form 6D in lower-limb osteoarthritis.
abstract: BACKGROUND
  Co-morbidities can influence generic measurement of health indirect utility. We investigated their impact to assess indirect utility with the Medical Outcomes Study Short Form 6D (SF-6D) in patients with osteoarthritis (OA).
  
  
  METHODS
  In patients with hip and knee OA from the Knee and Hip Osteo-Arthritis Long-term Assessment (KHOALA) study, co-morbidities were assessed by the Functional Co-morbidity Index. Multivariate linear regressions were used to determine predictors of utility score.
  
  
  RESULTS
  For the 878 patients included, the mean (standard deviation (SD)) utility score for 808 patients was 0.66 (11; range 0.32-1.00) and mean number of co-morbidities 2.05 (1.58). Number of co-morbidities (beta = -0.30; p = 0.002), psychiatric disease (beta = -0.043; p < 0.0001) and degenerative disc disease (beta = -0.014; p = 0.018) were predictors of low utility score. The WOMAC functional score had a higher significant effect (beta = -0.003; p < 0.0001) and explained a higher percentage of the model variance.
  
  
  CONCLUSIONS
  Compared to greater negative effect of functional severity of OA, co-morbidities have a negative but relatively marginal impact on indirect utility score. This suggests that, clinically, considering the functional severity of OA remains a first priority.
authors.affiliation: Université de Lorraine, Paris Descartes University, APEMAC, EA 4360, F-54 000, France.
authors.forename: Kossar
authors.initials: K
authors.lastname: Hosseini
authors.forename: Cécile
authors.initials: C
authors.lastname: Gaujoux-Viala
authors.forename: Joel
authors.initials: J
authors.lastname: Coste
authors.forename: Jacques
authors.initials: J
authors.lastname: Pouchot
authors.forename: Bruno
authors.initials: B
authors.lastname: Fautrel
authors.forename: Anne-Christine
authors.initials: AC
authors.lastname: Rat
authors.forename: Francis
authors.initials: F
authors.lastname: Guillemin
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000453:epidemiology* / Q000503:physiopathology; D020370:Osteoarthritis, Knee / Q000453:epidemiology* / Q000503:physiopathology; D012720:Severity of Illness Index