title: The effect of co-morbidities on health-related quality of life in patients placed on the waiting list for total joint replacement.
abstract: BACKGROUND
  Co-morbidity is a powerful predictor of health care outcomes and costs, as well as an important cofounder in epidemiologic studies. The effect of co-morbidities is generally related to mortality or complications. This study evaluated the association between co-morbidity and health-related quality of life (HRQoL) in patients awaiting total joint replacement.
  
  
  METHODS
  A total of 893 patients were recruited to the study between August 2002 and November 2003 in four Finnish hospitals. The effect of co-morbidity on HRQoL was measured by the generic 15D instrument and by a Visual Analog Scale (VAS). Comparative variance analysis of socio-demographic and clinical characteristics was described by using either an independent samples t-test or the Chi-square test. The differences in each of the 15D dimensions and the overall 15D single index score for patients were calculated. Two-sided p-values were calculated with the Levene Test for Equality of Variances.
  
  
  RESULTS
  Patients with co-morbidity totaled 649; the incidence of co-morbidity was 73%. The mean number of co-morbidities among the patients was two. At baseline the 15D score in patients with and without co-morbidity was 0.778 vs 0.816, respectively. The difference of the score (0.038) was clinically and statistically significant (P < 0.001). The patients' scores with and without co-morbidity on the different 15D dimensions related to osteoarthritis-moving, sleeping, usual activities, discomfort and symptoms, vitality and sexual activity-were low in both groups. Patients with co-morbidity scored lower on the dimensions of moving, vitality and sexual activity compared to the patients without co-morbidity. Co-morbidity was significantly associated with a reduced HRQoL. Patients without co-morbidity had poorer VAS, arthritis had strong effect to their quality of life compared to the patients with co-morbidity.
  
  
  CONCLUSIONS
  Assessing co-morbidity in patients placed on the waiting list for joint replacement may be useful method to prioritization in medical decision-making for healthcare delivery. The assessment of co-morbidities during waiting time is important as well as evaluating how the co-morbidity may affect the final outcomes of the total joint replacement.
authors.affiliation: National Research and Development Centre for Welfare and Health, Helsinki, Finland. ulla.tuominen@stakes.fi
authors.forename: Ulla
authors.initials: U
authors.lastname: Tuominen
authors.forename: Marja
authors.initials: M
authors.lastname: Blom
authors.forename: Johanna
authors.initials: J
authors.lastname: Hirvonen
authors.forename: Seppo
authors.initials: S
authors.lastname: Seitsalo
authors.forename: Matti
authors.initials: M
authors.lastname: Lehto
authors.forename: Pekka
authors.initials: P
authors.lastname: Paavolainen
authors.forename: Kalevi
authors.initials: K
authors.lastname: Hietanieni
authors.forename: Pekka
authors.initials: P
authors.lastname: Rissanen
authors.forename: Harri
authors.initials: H
authors.lastname: Sintonen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000706:statistics & numerical data*; D019645:Arthroplasty, Replacement, Knee / Q000706:statistics & numerical data*; D015897:Comorbidity; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000453:epidemiology*; D020370:Osteoarthritis, Knee / Q000453:epidemiology*; D010147:Pain Measurement; D011788:Quality of Life; D011795:Surveys and Questionnaires; D014850:Waiting Lists