Effects of Intensive Diet and Exercise on Knee Joint Loads, Inflammation, and Clinical Outcomes Among Overweight and Obese Adults With Knee Osteoarthritis: The IDEA Randomized Clinical Trial

• Published in: JAMA : the journal of the American Medical Association 2013-09, Vol.310 (12), p.1263-1273
• Main Authors: Messier, Stephen P, Mihalko, Shannon L, Legault, Claudine, Miller, Gary D, Nicklas, Barbara J, DeVita, Paul, Beavers, Daniel P, Hunter, David J, Lyles, Mary F, Eckstein, Felix, Williamson, Jeff D, Carr, J. Jeffery, Guermazi, Ali, Loeser, Richard F
• Format: Article
• Language: English
• Subjects: Adults; Aged; Biological and medical sciences; Biomarkers - blood; Biomechanical Phenomena; Body Mass Index; Clinical outcomes; Clinical trials; Diet; Diet, Reducing; Diseases of the osteoarticular system; Exercise; Exercise Therapy; Female; General aspects; Humans; Inflammation; Interleukin-6 - blood; Knee; Male; Medical sciences; Metabolic diseases; Middle Aged; Obesity; Obesity - complications; Osteoarthritis; Osteoarthritis, Knee - complications; Osteoarthritis, Knee - immunology; Osteoarthritis, Knee - physiopathology; Osteoarthritis, Knee - therapy; Overweight - complications; Pain Measurement; Quality of Life; Self Report; Single-Blind Method; Treatment Outcome; Weight Loss; Weight-Bearing
• ISSN: 0098-7484; 1538-3598
• DOI: 10.1001/jama.2013.277669

IMPORTANCE Knee osteoarthritis (OA), a common cause of chronic pain and disability, has biomechanical and inflammatory origins and is exacerbated by obesity. OBJECTIVE To determine whether a ≥10% reduction in body weight induced by diet, with or without exercise, would improve mechanistic and clinical outcomes more than exercise alone. DESIGN, SETTING, AND PARTICIPANTS Single-blind, 18-month, randomized clinical trial at Wake Forest University between July 2006 and April 2011. The diet and exercise interventions were center-based with options for the exercise groups to transition to a home-based program. Participants were 454 overweight and obese older community-dwelling adults (age ≥55 years with body mass index of 27-41) with pain and radiographic knee OA. INTERVENTIONS Intensive diet-induced weight loss plus exercise, intensive diet-induced weight loss, or exercise. MAIN OUTCOMES AND MEASURES Mechanistic primary outcomes: knee joint compressive force and plasma IL-6 levels; secondary clinical outcomes: self-reported pain (range, 0-20), function (range, 0-68), mobility, and health-related quality of life (range, 0-100). RESULTS Three hundred ninety-nine participants (88%) completed the study. Mean weight loss for diet + exercise participants was 10.6 kg (11.4%); for the diet group, 8.9 kg (9.5%); and for the exercise group, 1.8 kg (2.0%). After 18 months, knee compressive forces were lower in diet participants (mean, 2487 N; 95% CI, 2393 to 2581) compared with exercise participants (2687 N; 95% CI, 2590 to 2784, pairwise difference [Δ]exercise vs diet = 200 N; 95% CI, 55 to 345; P = .007). Concentrations of IL-6 were lower in diet + exercise (2.7 pg/mL; 95% CI, 2.5 to 3.0) and diet participants (2.7 pg/mL; 95% CI, 2.4 to 3.0) compared with exercise participants (3.1 pg/mL; 95% CI, 2.9 to 3.4; Δexercise vs diet + exercise = 0.39 pg/mL; 95% CI, −0.03 to 0.81; P = .007; Δexercise vs diet = 0.43 pg/mL; 95% CI, 0.01 to 0.85, P = .006). The diet + exercise group had less pain (3.6; 95% CI, 3.2 to 4.1) and better function (14.1; 95% CI, 12.6 to 15.6) than both the diet group (4.8; 95% CI, 4.3 to 5.2) and exercise group (4.7; 95% CI, 4.2 to 5.1, Δexercise vs diet + exercise = 1.02; 95% CI, 0.33 to 1.71; Ppain = .004; 18.4; 95% CI, 16.9 to 19.9; Δexercise vs diet + exercise, 4.29; 95% CI, 2.07 to 6.50; Pfunction