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.
OBJECTIVE
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.


METHODS
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.


METHODS
Intensive diet-induced weight loss plus exercise, intensive diet-induced weight loss, or exercise.


METHODS
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; Δ(exercise vs diet + exercise) = 0.39 pg/mL; 95% CI, -0.03 to 0.81; P = .007; Δ(exercise 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, Δ(exercise vs diet + exercise) = 1.02; 95% CI, 0.33 to 1.71; P(pain) = .004; 18.4; 95% CI, 16.9 to 19.9; Δ(exercise vs diet + exercise), 4.29; 95% CI, 2.07 to 6.50; P(function )< .001). The diet + exercise group (44.7; 95% CI, 43.4 to 46.0) also had better physical health-related quality of life scores than the exercise group (41.9; 95% CI, 40.5 to 43.2; Δ(exercise vs diet + exercise) = -2.81; 95% CI, -4.76 to -0.86; P = .005).


CONCLUSIONS
Among overweight and obese adults with knee OA, after 18 months, participants in the diet + exercise and diet groups had more weight loss and greater reductions in IL-6 levels than those in the exercise group; those in the diet group had greater reductions in knee compressive force than those in the exercise group.


BACKGROUND
clinicaltrials.gov Identifier: NCT00381290.
Department of Health and Exercise Science, Wake Forest University, Winston-Salem, North Carolina 27109, USA. messier@wfu.edu
Stephen P
SP
Messier
Shannon L
SL
Mihalko
Claudine
C
Legault
Gary D
GD
Miller
Barbara J
BJ
Nicklas
Paul
P
DeVita
Daniel P
DP
Beavers
David J
DJ
Hunter
Mary F
MF
Lyles
Felix
F
Eckstein
Jeff D
JD
Williamson
J Jeffery
JJ
Carr
Ali
A
Guermazi
Richard F
RF
Loeser
D000368:Aged; D015415:Biomarkers / Q000097:blood; D001696:Biomechanical Phenomena; D015992:Body Mass Index; D004038:Diet, Reducing; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D007249:Inflammation; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D020370:Osteoarthritis, Knee / Q000150:complications / Q000276:immunology / Q000503:physiopathology* / Q000628:therapy*; D050177:Overweight / Q000150:complications*; D010147:Pain Measurement; D011788:Quality of Life; D057566:Self Report; D016037:Single-Blind Method; D016896:Treatment Outcome; D015431:Weight Loss; D016474:Weight-Bearing
D015415:Biomarkers; D015850:Interleukin-6