title: Prevalence of knee osteoarthritis, risk factors, and quality of life: The Fifth Korean National Health And Nutrition Examination Survey.
abstract: OBJECTIVE
  Although there have been regional population-based studies on the prevalence of knee osteoarthritis (KOA) and its risk factors in South Koreans, those studies in common had limited external validity. This study aims to estimate the national prevalence of KOA and its risk factors using a complex sampling design.
  
  
  METHODS
  This was a cross-sectional study including 9512 participants aged ≥ 50 years of The Fifth Korean National Health and Nutrition Examination Survey, who were selected using two-step stratified clustered equal-probability systematic sampling. Radiographic KOA (RKOA) was defined as a Kellgren-Lawrence grade of ≥ 2. Symptoms of KOA were evaluated through a health interview. Obesity was defined as a body mass index ≥ 27.5 kg/m2.Quality of life was measured by the Korean version of European Quality of Life Questionnaire (EQ-5D).
  
  
  RESULTS
  The prevalence of RKOA was 21.1% (95% CI: 19.6-22.8%) in men, and 43.8% (42.0-45.6%) in women. The prevalence of symptomatic RKOA (SRKOA) was 4.4% (3.8-5.2%) and 19.2% (17.9-20.6%) in men and women, respectively. The EQ-5D index was lower in participants with KOA. When plotted against mean age and prevalence of obesity, regions with a higher mean age and prevalence of obesity had higher prevalence of KOA, which was also observed at the individual level. The prevalence of SRKOA was 36.6% (29.7-44.1%) in women in Jeju province.
  
  
  CONCLUSIONS
  The prevalence of SRKOA in women reached 36.6% in high-risk groups accompanied by low quality of life. The results suggest that the disease burden of KOA is high in South Korea.
authors.affiliation: Department of Internal Medicine, Haeundae Paik Hospital, Inje University College of Medicine, Busan, South Korea.
authors.forename: Sunggun
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Radiology, Myongji Hospital, Goyang, South Korea.
authors.forename: Seon-Jeong
authors.initials: SJ
authors.lastname: Kim
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D009765:Obesity / Q000175:diagnosis / Q000453:epidemiology; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000523:psychology; D015995:Prevalence; D011788:Quality of Life; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D017678:Sex Distribution
keywords: epidemiology; osteoarthritis