20% of us experience joint complications, so there's been a lot of sporadic talk over the years about
it. What are they testing for? Ankylosing spondylitis?
I found this interesting:
G&H How frequently does arthritis occur in patients with inflammatory bowel disease?
TRO There are 2 types of joint problems that can occur in patients with inflammatory bowel disease (IBD): arthritis, which is inflammation, and arthralgia, which is pain without inflammation. Arthralgia is more common among patients with IBD, occurring in 40-50% of patients, which is a rate similar to that of the general population; arthritis occurs in approximately 15—20% of Crohn's disease (CD) patients and approximately 10% of ulcerative colitis (UC) patients at some stage during their disease course.
G&H What types of arthritis are most common in patients with IBD?
TRO Approximately 60—70% of the arthritis seen in IBD patients is peripheral arthritis, in which the large joints are affected, and this arthritis is typically an oligoarthritis, meaning that fewer than 5 joints are affected. The most commonly affected joints are the knees, ankles, wrists, elbows, and hips. A smaller proportion of IBD patients have symmetrical polyarthritis, which has a presentation similar to that of rheumatoid arthritis; these patients can develop inflammation in any joints, but typically the small joints of the hands are affected. Finally, 1—6% of all IBD patients develop ankylosing spondylitis, which is a progressive inflammatory arthropathy affecting the sacroiliac joints and the spine. These patients develop gradual fusion of the spine over a period of time. While large joint arthritis is nearly always associated with active IBD, ankylosing spondylitis and small joint polyarthritis can flare up independently of the patient's IBD.
G&H What mechanism underlies the development of arthritis in patients with IBD?
TRO The development of arthritis in these patients definitely involves a genetic component, which probably makes patients susceptible to luminal microbiota that can trigger arthritis. The arthritis associated with IBD is classified as a seronegative spondyloarthropathy; all the conditions in this group involve the development of arthritis without the presence of autoantibodies, and all these conditions are associated with an increased risk of developing ankylosing spondylitis. Ankylosing spon-dylitis is known to be strongly associated with HLA-B27, which is a particular variant of an HLA gene that controls the immune response, and peripheral arthritis in IBD patients is also associated with HLA-B27, although less strongly; this common association probably accounts for the increase in ankylosing spondylitis among patients with seronegative spondyloarthropathy. However, peripheral arthritis in IBD patients has an even stronger association with a rare HLA allele called HLA-DR103. This allele is present in approximately 35% of patients with large joint arthritis and in up to 65% of patients who have more than 1 episode of large joint arthritis. In comparison, this allele occurs in only 1—3% of the general population. How this genetic association results in arthritis among IBD patients is largely speculation.