(dailyRx News) Inflammation is the reason patients with rheumatoid arthritis develop swollen and painful joints. But inflammation is not unique to rheumatoid arthritis; it is also behind other painful joint conditions.
Diseases like ankylosing spondylitis may be more common among patients with rheumatoid arthritis than previously thought, according to recent findings.
The researchers found that 16.8 percent of patients with rheumatoid arthritis (28 patients) had inflammatory back pain, according to Calin criteria.
Researchers from Dokuz Eylül University in Turkey set out to study rates of inflammatory back pain, ankylosing spondylitis and spondyloarthritis among patients with rheumatoid arthritis.
Spondyloarthritis is the name used for a group of inflammatory diseases that includes ankylosing spondylitis, psoriatic arthritis and other rheumatic diseases.
People who meet the Calin criteria for inflammatory back pain have four of the following five signs:
- Older than 40 years of age
- Back pain that has persisted for more than 3 months
- Insidious onset, or back pain that develops slowly
- Improvement with exercise
- Early morning stiffness
To calculate rates of spondyloarthritis, the researchers used a few measures.
According to the modified New York criteria, 1.8 percent of patients (three patients) had ankylosing spondylitis.
People who meet the modified New York criteria have visible X-ray changes to the pair of joints in the pelvis and one of the following:
- Low back pain that has lasted for at least 3 months and that is improved by exercise and not reduced by rest
- Limited motion in the lumbar spine (the part of the spine between the rib cage and pelvis)
- Less chest expansion than normal
According to two different measures, 18.6 percent (31) and 15.6 percent (26) of patients with rheumatoid arthritis had spondyloarthritis.
Axial spondyloarthritis - a form of spondyloarthritis in which the main symptom is back pain - was found in 5.3 percent of patients (nine patients).
"This study suggests that the prevalence of spondyloarthritis features in patients with rheumatoid arthritis may be much higher than expected," the authors concluded.
The study was published November 6 in Rheumatology International.