Body Weight Changes and Corresponding Changes
in Pain and Function in Persons With
Symptomatic Knee Osteoarthritis: A Cohort Study
DANIEL L. RIDDLE1AND PAUL W. STRATFORD2
Objective. To determine if a dose-response relationship exists between percentage changes in body weight in persons
with symptomatic knee osteoarthritis (OA) and self-reported pain and function.
Methods. Data from persons in the Osteoarthritis Initiative (OAI) and the Multicenter Osteoarthritis (MOST) study data
sets (n ? 1,410) with symptomatic function-limiting knee OA were studied. For the OAI, we used baseline and 3-year
followup data, while for the MOST study, baseline and 30-month data were used. Key outcome variables were Western
Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function and pain change scores. In addition
to covariates, the predictor variable of interest was the extent of weight change over the study period divided into 5
categories representing different percentages of body weight change.
Results. A significant dose-response relationship (P < 0.003) was found between the extent of percentage change in body
weight and the extent of change in WOMAC physical function and WOMAC pain scores. For example, persons who gained
>10% of body weight had WOMAC physical function score changes of ?5.4 (95% confidence interval ?8.7, ?2.00) points,
indicating worsening physical function relative to the reference group of persons with weight changes between <5%
weight gain and <5% weight reduction.
Conclusion. Our data suggest a dose-response relationship exists between changes in body weight and corresponding
changes in pain and function. The threshold for this response gradient appears to be body weight shifts of >10%. Weight
changes of >10% have the potential to lead to important changes in pain and function for patient groups as well as
Osteoarthritis (OA) of the knee has multiple causes, but
one of the more powerful risk factors for OA onset and
progression is excessive body weight (1,2). The Framing-
ham study, for example, reported that women who lost at
least 5 kg had a 50% reduction in the odds of developing
symptomatic knee OA (3). Given the high costs and high
prevalence of knee OA, many researchers have focused on
attempts to identify interventions that reduce the body
weight of persons with OA who are overweight or obese
A meta-analysis that examined the effects of various
approaches to weight reduction with or without cointer-
ventions for persons with symptomatic knee OA found
that a weight reduction of 5% of body weight was associ-
This article was prepared using Multicenter Osteoarthri-
tis study data and does not necessarily reflect the opinions
or views of the Multicenter Osteoarthritis study investiga-
tors. This article was prepared using an Osteoarthritis Ini-
tiative public use data set and does not necessarily reflect
the opinions or views of the Osteoarthritis Initiative inves-
tigators, the NIH, or the private funding partners.
The Multicenter Osteoarthritis (MOST) study is com-
AG18947, AG19069) funded by the NIH, a branch of the
Department of Health and Human Services, and conducted
by the MOST study investigators. The Osteoarthritis Initia-
tive (OAI) is a public-private partnership comprised of 5
contracts (N01-AR-2-2258, N01-AR-2-2259, N01-AR-2-2260,
N01-AR-2-2261, N01-AR-2-2262) funded by the NIH, a
branch of the Department of Health and Human Services,
and conducted by the OAI study investigators. Private fund-
ing partners include Merck, Novartis, GlaxoSmithKline,
and Pfizer. Private sector funding for the OAI is managed by
the Foundation for the NIH.
1Daniel L. Riddle, PT, PhD: Departments of Physical Ther-
apy and Orthopaedic Surgery, Virginia Commonwealth
University, Richmond;2Paul W. Stratford, PT, MSc: McMas-
ter University, Hamilton, Ontario, Canada.
Dr. Riddle has received consultancy fees, speaking fees,
and/or honoraria (less than $10,000) from the Physical Ther-
apy Editorial Board.
Address correspondence to Daniel L. Riddle, PT, PhD,
Virginia Commonwealth University Department of Phys-
ical Therapy, PO Box 980224, Richmond, VA 23298-0224.
Submitted for publication October 18, 2011; accepted in
revised form March 26, 2012.
Arthritis Care & Research
Vol. 65, No. 1, January 2013, pp 15–22
© 2013, American College of Rheumatology
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22 Riddle and Stratford