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Clue Found to Early Detection, Treatment of
Osteoarthritis
Jan. 7, 2005 – Researchers seeking to find a
biomarker to detect osteoarthritis (OA) in its earliest stages, which
could help treatment, think high levels of hyaluronic acid may indicate
a link to severe OA of the knees and hips. OA is a common cause of pain
and disability among older Americans.
OA of the knee affects up to 6 percent of the older
population, while OA of the hip affects about 3 percent. While
treatments vary, there is hope that early intervention – before joint
destruction can be clearly seen and measured on an X-ray image will
improve outcomes.
The need for better ways to assess OA's activity
from its onset has led researchers to investigate possible biomarkers,
particularly those related to cartilage and bone turnover. A biomarker
is substance found in the blood or joint fluid whose levels can be used
to assess the presence or activity of a disease. Among likely candidates
for a biomarker for OA is hyaluronic acid, also known as hyaluronan or
simply HA. HA is a component of connective tissue that is widely
distributed throughout the body and plays an important role in joint
function.
A recent study, published in the January 2005 issue
of
Arthritis & Rheumatism, strongly supports the relationship between
increased production of HA and increased risk for OA, specifically of
the knees and hips, among ethnically diverse men and women.
Led by Drs. Alan L. Elliott and Joanne M. Jordan of
the Thurston Arthritis Research Center, University of North Carolina at
Chapel Hill, and Dr. Virginia B. Kraus of Duke University Medical
Center, the study drew its subjects from a large, local population of
participants in the Johnston County Osteoarthritis Project.
The study group comprised 753 subjects, including 120 African American
men, 245 African American women, 199 Caucasian men, and 189 Caucasian
women. The average age of the participants was just shy of 62 years and
the mean body mass index was on the heavy side, just over 30. Of the
total subjects, 455 had mild to severe knee OA, confirmed by
radiographs. 152 of the subjects with knee OA also had hip OA. In 52 of
these individuals with OA, the disease had progressed to both knees and
both hips.
The research team obtained a blood sample from
every participant and analyzed each for its concentration of HA. Across
the board, Caucasians had higher serum HA levels than African Americans
and men had higher serum HA levels than women. The most compelling
differences in HA levels, however, were between the 298 subjects without
any radiographic evidence of OA and the 455 OA participants – especially
those with two or more joints affected.
As the presence and amount of OA involvement
increased, so did the HA levels. On average, the concentration of HA was
higher in patients with severe knee OA compared to those in the moderate
stages of disease, higher in patients with two diseased knees compared
to those with a single diseased knee, and higher in patients with hip OA
in addition to knee OA compared to those with knee OA alone. When
adjusted for ethnicity, sex, age, and BMI, the associations between
elevated HA levels and all definitions of OA status remained
statistically significant.
Also significantly, researchers found no
independent correlations between elevated levels of HA and other adverse
health conditions reported by the subjects, including high blood
pressure, diabetes, chronic pulmonary disease, persistent liver, kidney,
bladder, and prostate problems, and cancer. Only one condition showed a
sustained independent relationship with elevated HA after statistical
adjustment: gout, which, like OA, is marked by joint inflammation and
damage.
"The results of this study suggest that serum HA
measurements are useful for assessing overall OA load," Dr Elliott
notes. "The lack of independent associations of serum HA levels with
several comorbid conditions commonly associated with OA further supports
its promise in the study of OA."
"Serum Hyaluronan
Levels and Radiographic Knee and Hip Osteoarthritis in African Americans
and Caucasians in the Johnston County Osteoarthritis Project," Alan L.
Elliott, Virginia B. Kraus, Gheorghe Luta, Thomas Stabler, Jordan B.
Renner, Janice Woodard, Anca D. Dragomir, Charles G. Helmick, Marc C.
Hochberg, and Joanne M. Jordan, is in Arthritis & Rheumatism, January
2005.
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