title: Knee osteoarthritis, body mass index and pain: data from the Osteoarthritis Initiative.
abstract: OBJECTIVE
  This study aimed to determine whether BMI increases knee pain as measured from self-reported surveys even when controlling for OA severity as measured by osteophytes and joint space narrowing visible on X-rays.
  
  
  METHODS
  Data available through the Osteoarthritis Initiative (OAI) were analysed, which included a sample of 4769 individuals, to answer the above question regarding OA, excess weight and pain. OA severity was assessed through baseline X-rays on right knees that were scored on a composite quasi-Kellgren and Lawrence grade. Weight was assessed through BMI. Pain was assessed through self-reports of the WOMAC pain subset as well as a 30-day pain severity question based on a 0-10 scale. Data were analysed using SPSS and analyses of covariance (ANCOVAs) were run to examine models adjusted for age, smoking, prior injury, pain medication and Heberden's nodes. Critical alpha levels were set at 0.05.
  
  
  RESULTS
  The results reported here confirm that knee pain does increase with OA severity. However, ANCOVA multiple regressions with controls reveal that even when taking into account OA severity, individuals with higher BMIs experience greater pain than individuals with lower BMIs.
  
  
  CONCLUSIONS
  Weight loss may reduce knee OA pain even if the osteological symptoms are not treated.
authors.affiliation: Department of Anthropology, San Jose State University, San Jose, CA, USA. elizabeth.weiss@sjsu.edu.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Weiss
mesh_terms: D000368:Aged; D018771:Arthralgia / Q000175:diagnosis* / Q000209:etiology / Q000534:rehabilitation; D015992:Body Mass Index; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications / Q000175:diagnosis*; D010147:Pain Measurement / Q000379:methods*; D011859:Radiography; D012307:Risk Factors; D012720:Severity of Illness Index
keywords: body mass index; knee osteoarthritis; pain