title: The impact of co-morbidity on health-related quality of life in rheumatoid arthritis and osteoarthritis patients.
abstract: OBJECTIVE
  We investigated whether comorbidities differentially impacted health-related quality of life (HRQOL) for rheumatoid arthritis (RA) and osteoarthritis (OA) patients.
  
  
  METHODS
  Adult patients with self-reported doctor-diagnosed RA (n=159) or OA (n=149) were recruited from multiple sources and completed an online cross-sectional survey. Patients self-reported sociodemographic variables, arthritis severity and comorbid conditions. HRQOL was assessed using the SF-12v2 and comorbidity counts were assigned using an expanded Functional Comorbidities Index. HRQOL (8 domain and 2 composite (physical and mental health) scores) was compared with norm-based general US population scores and between RA and OA patients to determine if they significantly differed from one another. Linear regression was used to test whether comorbidity count was associated with the physical and mental health of RA and OA patients.
  
  
  RESULTS
  OA and RA patients experienced significantly worse HRQOL across all dimensions compared with that of the general US population. There were no significant differences between RA and OA patients on any HRQOL dimension. A higher comorbidity count was associated with worse physical (p=0.0007) and mental (p=0.0295) health scores when controlling for patient gender, age, education, and arthritis severity.
  
  
  CONCLUSIONS
  Arthritis negatively impacted patients' HRQOL. OA patients in our sample perceived their condition as similarly disabling in terms of physical and mental health as RA patients. Arthritis patients with more chronic comorbid conditions may be at particular risk for poor physical and mental health. Providers should discuss management of comorbid conditions with arthritis patients.
authors.affiliation: UNC Eshelman School of Pharmacy, Division of Pharmaceutical Outcomes and Policy, University of North Carolina, Chapel Hill, USA.
authors.forename: Lorie L
authors.initials: LL
authors.lastname: Geryk
authors.affiliation: UNC Eshelman School of Pharmacy, Division of Pharmaceutical Outcomes and Policy, University of North Carolina, Chapel Hill, USA.
authors.forename: Delesha M
authors.initials: DM
authors.lastname: Carpenter
authors.affiliation: UNC Eshelman School of Pharmacy, Division of Pharmaceutical Outcomes and Policy, University of North Carolina, Chapel Hill, USA.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Blalock
authors.affiliation: University of North Carolina, Gillings School of Global Public Health, Department of Health Behavior, University of North Carolina, Chapel Hill, USA.
authors.forename: Robert F
authors.initials: RF
authors.lastname: DeVellis
authors.affiliation: Thurston Arthritis Research Center, University of North Carolina, Chapel Hill, USA.
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Jordan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000523:psychology*; D015897:Comorbidity; D017281:Cost of Illness; D003430:Cross-Sectional Studies; D005260:Female; D006304:Health Status; D006306:Health Surveys; D006801:Humans; D020407:Internet; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000523:psychology*; D011788:Quality of Life; D012307:Risk Factors; D057566:Self Report; D012720:Severity of Illness Index; D014481:United States / Q000453:epidemiology; D055815:Young Adult