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Media Contact: Tammy McCoy
(404) 633-3777, ext. 805
Embargoed for Release at 6:15 pm
ET , Sunday Oct. 17, 2004
Arthritis News
IMPROVED VITAMIN D LEVELS MAY DECREASE KNEE DISABILITY
IN OSTEOARTHRITIS PATIENTS
SAN ANTONIO, TEXAS - Increased vitamin D levels appear to improve
muscle strength and physical function for vitamin D-deficient
patients with knee osteoarthritis, according to research presented
this week at the American College of Rheumatology Annual Scientific
Meeting in San Antonio, Texas.
While previous studies have associated vitamin D deficiencies
with an increased risk for severity of knee osteoarthritis, this
is the first look at vitamin levels in relation to pain and disability.
The 221 patients, average age 67 years, participating in this
study were measured for changes in pain, physical function, muscle
strength and serum levels of vitamin D (measurable amounts of
vitamin D in the blood) two or more times across a 15- and 30-month
period. At the outset, the 48 percent of patients with low levels
of vitamin D (at or below the minimal 20 ng/ml needed to satisfy
the body's requirements) experienced more pain and disability
than those with levels above 20 ng/ml. Those with deficient serum
vitamin D were also weaker, but this was not significant.
The study also found that changes in vitamin D status over time
predicted changes in disability. Those with sufficient serum
vitamin D that became deficient over time experienced worsening
disability scores, while those with deficient serum vitamin D
that became sufficient over time improved their disability scores.
Change in serum vitamin D levels also showed a similar pattern
in changes in pain but this was not significant.
Vitamin D, which comes primarily from exposure to sunlight,
promotes the absorption of calcium and phosphorus in bone mineralization,
growth and repair. Sources of vitamin D are available to a lesser
extent from dietary sources typically found in fortified margarine,
oily fish, liver, fortified breakfast cereals and dairy products.
However, the elderly are less efficient at producing vitamin
D from sunlight and absorbing it from food. To address their
higher risk for D deficiency, the elderly population is often
directed to take a vitamin D supplement of 400-600 IU per day.
(Exposure to sun should be limited to five to 15 minutes on the
face, hands or arms, or arms and legs.)
"Data suggests that many people may be vitamin D deficient,
especially those living in the northern hemisphere and darker
skinned individuals," said Kristin Baker, PhD, Clinical Epidemiology
and Research Training Unit, Boston University Boston, Massachusetts,
and an investigator in the study. "The good news is vitamin D
levels are easily modifiable through safe, short-term exposure
to sun and/or dietary intake, and may lessen the disability and
pain of osteoarthritis."
The American College of Rheumatology is the professional organization
for rheumatologists and health professionals who share a dedication
to healing, preventing disability and curing arthritis and related
rheumatic and musculoskeletal diseases. For more information
on the ACR's annual meeting, see www.rheumatology.org/annual.
###
Editor's Notes: Dr. Baker will present this research during
a scientific session at the ACR Annual Scientific Meeting from
2:30 - 2:45 pm CT (3:30 - 3:45 pm ET) on Wednesday, October
20, in the Theatre of the Henry B. Gonzalez Convention Center.
She will be available for media questions during a briefing
at 8:30 am CT (9:30am ET) on Monday, October 18, in the on-site
Press Conference Room, Room 218.
Presentation Number: 1755
Hypovitaminosis D and its Association with Muscle
Strength, Pain and Physical Function in Knee Osteoarthritis (OA):
A 30-month Longitudinal, Observatonal Study
K. Baker, YQ Zhang, J. Goggins, M. Clancy, M. LaValley, JB Niu,
D. Felson. Boston University, Boston, MA
While low serum levels of vitamin D (Vit D) have been associated
with an increased risk for progression of knee OA, the relationship
to pain and disability in knee OA has not been investigated.
In cross sectional studies Vit D has been associated with muscle
weakness and disability. Also, recently, pain in persons with
cancer was found associated with hypovitaminosis D, leading to
the hypothesis that low Vit D levels contribute to worse pain
in many disorders. The purpose of this study was to evaluate
the relationship of Vit D to pain, physical function, and muscle
strength in subjects with symptomatic knee OA.
Subjects were recruited from the Boston VA Medical Center and
surrounding community. Eligibility criteria included evidence
of knee OA by radiograph and pain in the knee on most days of
the previous month. Measurements at baseline, 15, and 30-months
included WOMAC pain subscale (Likert scale, 0-20), WOMAC physical
function scale (0-68), serum levels of Vit D, and isokinetic
strength of concentric knee extension (at 60 0 /sec; 3 repetitions
with the maximal strength used). We looked at the association
of baseline serum Vit D with baseline pain, physical function
and muscle strength, and change in serum Vit D and change in
pain, physical function and muscle strength. For the analysis
of baseline Vit D with baseline WOMAC pain and physical function
and baseline muscle strength, serum Vit D was dichotomized into
those deficient (≤ 20ng/ml) and those not deficient (> 20
ng/ml, minimal amount to satisfy the body's requirement for Vit
D). Outcomes were analyzed using regression or repeated measures
regression analyses adjusted for sex.
221 subjects (63% male, mean age 67 ± 10, mean BMI 31 ± 6)
had both serum Vit D and WOMAC at 2 or more time points. 48%
of subjects had Vit D levels below 20 ng/ml. Low baseline Vit
D was associated with more pain and disability. Those with low
baseline vitamin D were weaker but this association was not significant.
For the change analysis, we saw an association between positive
and negative changes in vitamin D and disability but not for
pain and muscle strength. Those that became deficient had more
pain and were weaker (with the exception of weakness in women)
but again this trend was not significant (see table for baseline
and change data).
In summary, we found that persons with low Vit D levels (≤ 20
ng/ml) had more knee pain and disability compared to those who
were not Vit D deficient. An increase in serum vitamin D over
30 months correlated with an improvement in WOMAC disability.
Association of Vitamin D
with Pain, Physical Function and Strength - LS means (SE) |
|
Baseline Vitamin D deficient - ≤ ng/ml
(14 ± 4 ng/ml) |
Baseline Vitamin D sufficient - ≥ 20 ng/ml
(27 ± 6 ng/ml) |
p value |
Vitamin D over 30 months
(no change) |
Vitamin D
over 30 months
(sufficient to deficient) |
Vitamin D over 30 months
(deficient to sufficient) |
p value |
WOMAC pain (0-20) |
8.0 (0.4) |
6.6 ( 0.4) |
<0.0001 |
7.1 ( 0.2) |
8.1 ( 0.8) |
6.6 ( 0.5) |
0.12 |
WOMAC disability
(0-68) |
26.9 (1.2) |
21.7 (1.3) |
<0.0001 |
23.8 (0.7) |
27.3 ( 2.3) |
21.8 ( 1.6) |
0.05 |
Strength (newtons)
by sex |
M: 75.8 ( 4.5)
F: 50.5 ( 3.3) |
M: 78.2 (4.5)
F: 56.2 ( 3.6) |
M: 0.6
F: 0.1 |
M: 77.9 ( 2.6)
F: 49.8 (1.9) |
M: 69.5 ( 6.9)
F: 56.1 ( 6.0) |
M: 83.6 ( 7.7)
F: 54.1 ( 4.7) |
M: 0.5
F: 0.3 |
Disclosure: K. Baker, None; Y. Zhang, None; J. Goggins,
None; M. Clancy, None; M. LaValley, None; J. Niu,
None; D. Felson, None.
