The Intensive Diet and Exercise for Arthritis (IDEA) trial: design and rationale.
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.
Messier
Stephen P
SP
Department of Health and Exercise Science, Wake Forest University, Winston-Salem, NC, USA. messier@wfu.edu
Legault
Claudine
C
Mihalko
Shannon
S
Miller
Gary D
GD
Loeser
Richard F
RF
DeVita
Paul
P
Lyles
Mary
M
Eckstein
Felix
F
Hunter
David J
DJ
Williamson
Jeff D
JD
Nicklas
Barbara J
BJ
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
D015415:Biomarkers; D018836:Inflammation Mediators