title: The Intensive Diet and Exercise for Arthritis (IDEA) trial: design and rationale.
abstract: BACKGROUND
  Obesity is the most modifiable risk factor, and dietary induced weight loss potentially the best nonpharmacologic intervention to prevent or to slow osteoarthritis (OA) disease progression. We are currently conducting a study to test the hypothesis that intensive weight loss will reduce inflammation and joint loads sufficiently to alter disease progression, either with or without exercise. This article describes the intervention, the empirical evidence to support it, and test-retest reliability data.
  
  
  METHODS
  This is a prospective, single-blind, randomized controlled trial. The study population consists of 450 overweight and obese (BMI = 27-40.5 kg/m2) older (age > or = 55 yrs) adults with tibiofemoral osteoarthritis. Participants are randomized to one of three 18-month interventions: intensive dietary restriction-plus-exercise; exercise-only; or intensive dietary restriction-only. The primary aims are to compare the effects of these interventions on inflammatory biomarkers and knee joint loads. Secondary aims will examine the effects of these interventions on function, pain, and mobility; the dose response to weight loss on disease progression; if inflammatory biomarkers and knee joint loads are mediators of the interventions; and the association between quadriceps strength and disease progression.
  
  
  RESULTS
  Test-retest reliability results indicated that the ICCs for knee joint load variables were excellent, ranging from 0.86 - 0.98. Knee flexion/extension moments were most affected by BMI, with lower reliability with the highest tertile of BMI. The reliability of the semi-quantitative scoring of the knee joint using MRI exceeded previously reported results, ranging from a low of 0.66 for synovitis to a high of 0.99 for bone marrow lesion size.
  
  
  CONCLUSIONS
  The IDEA trial has the potential to enhance our understanding of the OA disease process, refine weight loss and exercise recommendations in this prevalent disease, and reduce the burden of disability.
  
  
  BACKGROUND
  NCT00381290.
authors.affiliation: Department of Health and Exercise Science, Wake Forest University, Winston-Salem, NC, USA. messier@wfu.edu
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Messier
authors.forename: Claudine
authors.initials: C
authors.lastname: Legault
authors.forename: Shannon
authors.initials: S
authors.lastname: Mihalko
authors.forename: Gary D
authors.initials: GD
authors.lastname: Miller
authors.forename: Richard F
authors.initials: RF
authors.lastname: Loeser
authors.forename: Paul
authors.initials: P
authors.lastname: DeVita
authors.forename: Mary
authors.initials: M
authors.lastname: Lyles
authors.forename: Felix
authors.initials: F
authors.lastname: Eckstein
authors.forename: David J
authors.initials: DJ
authors.lastname: Hunter
authors.forename: Jeff D
authors.initials: JD
authors.lastname: Williamson
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Nicklas
mesh_terms: D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D003131:Combined Modality Therapy; D004185:Disability Evaluation; D005081:Exercise Therapy; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood; D007719:Knee Joint / Q000473:pathology / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D051346:Mobility Limitation; D009765:Obesity / Q000150:complications* / Q000503:physiopathology / Q000628:therapy; D020370:Osteoarthritis, Knee / Q000178:diet therapy / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D010146:Pain / Q000209:etiology / Q000517:prevention & control; D010147:Pain Measurement; D011237:Predictive Value of Tests; D011446:Prospective Studies; D020127:Recovery of Function; D015203:Reproducibility of Results; D012107:Research Design; D012720:Severity of Illness Index; D016037:Single-Blind Method; D013997:Time Factors; D016896:Treatment Outcome; D015431:Weight Loss; D016474:Weight-Bearing
chemical_list: D015415:Biomarkers; D018836:Inflammation Mediators