title: Association of knee pain and different definitions of knee osteoarthritis with health-related quality of life: a population-based cohort study in southern Sweden.
abstract: BACKGROUND
  While the impact of knee pain and knee osteoarthritis (OA) on health-related quality of life (HRQoL) has been investigated in the literature, there is a lack of knowledge on the impact of different definitions of OA on HRQoL. The main aim of this study was to measure and compare the impact of knee OA and its different definitions on HRQoL in the general population.
  
  
  METHODS
  A random sample of 1300 participants from Malmö, Sweden with pain in one or both knees in the past 12 months with duration ≥4 weeks and 650 participants without were invited to clinical and radiographic knee examination. A total of 1527 individuals with a mean (SD) age 69.4 (7.2) participated and responded to both generic (EQ-5D-3L) and disease-specific (the Knee injury and Osteoarthritis Outcome Score) questionnaires. Knee pain was defined as pain during the last month during most of the days. Knee OA was defined radiographically (equivalent to Kellgren and Lawrence grade ≥2) and clinically according to the American College of Rheumatology (ACR) criteria.
  
  
  RESULTS
  Of participants with either knee pain or knee OA or both, 7 % reported no problem for the EQ-5D-3L attributes. The corresponding proportion among references (neither knee pain nor OA) was 42 %. The participants with knee pain and OA had all HRQoL measures lower compared to those with knee pain but no OA. The ACR clinical definition of knee OA was associated with lower HRQoL than the definition based on radiographic knee OA (adjusted difference -0.08 in UK EQ-5D-3L index score).
  
  
  CONCLUSIONS
  Applying different definitions of knee OA result in different levels of HRQoL and this is mainly explained by the knee pain experience. These differences may lead to discrepant conclusions from cost-utility analyses.
authors: Clinical Epidemiology Unit, Orthopaedics, Department of Clinical Sciences-Lund, Lund University, Lund, Sweden. aliasghar.ahmad_kiadaliri@med.lu.se.|Health Services Management Research Center, Institute for Futures Studies in Health, Kerman University of Medical Sciences, Kerman, Iran. aliasghar.ahmad_kiadaliri@med.lu.se.|Skånes University Hospital, Clinical Epidemiology Unit, Klinikgatan 22, SE-221 85, Lund, Sweden. aliasghar.ahmad_kiadaliri@med.lu.se.
authors: Aliasghar A
authors: AA
authors: Kiadaliri
authors: Astra Zeneca R&D, Mölndal, Sweden.
authors: Carl Johan
authors: CJ
authors: Lamm
authors: Astra Zeneca R&D, Gothenburg, Sweden.
authors: Maria Gerhardsson
authors: MG
authors: de Verdier
authors: Cardiovascular Epidemiology, Department of Clinical Sciences, Lund University, Malmö, Sweden.
authors: Gunnar
authors: G
authors: Engström
authors: Clinical Epidemiology Unit, Orthopaedics, Department of Clinical Sciences-Lund, Lund University, Lund, Sweden.
authors: Aleksandra
authors: A
authors: Turkiewicz
authors: Clinical Epidemiology Unit, Orthopaedics, Department of Clinical Sciences-Lund, Lund University, Lund, Sweden.|Research Unit for Musculoskeletal Function and Physiotherapy, University of Southern Denmark, Odense, Denmark.|Department of Orthopedics and Traumatology, University of Southern Denmark, Odense, Denmark.
authors: L Stefan
authors: LS
authors: Lohmander
authors: Clinical Epidemiology Unit, Orthopaedics, Department of Clinical Sciences-Lund, Lund University, Lund, Sweden.|Epidemiology and Register Centre South, Skåne University Hospital, Lund, Sweden.|Clinical Epidemiology Research and Training Unit, Boston University School of Medicine, Boston, MA, USA.
authors: Martin
authors: M
authors: Englund
mesh_terms: D000328:Adult; D000368:Aged; D018771:Arthralgia / Q000523:psychology*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007719:Knee Joint; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology*; D011788:Quality of Life / Q000523:psychology*; D013548:Sweden
keywords: EQ-5D-3L; KOOS; Knee osteoarthritis; Knee pain; Quality of life; Sweden