Enteropathic Arthritis

Enteropathic arthritis is spondyloarthritis associated with inflammatory bowel disease (Crohn disease, ulcerative colitis).

• Occurs in 15 to 30% of IBD patients, with peripheral arthritis the commonest form.

• Type 1 peripheral (pauciarticular, under 5 joints, large joints, parallels bowel flares, self-limited); type 2 (polyarticular, over 5 joints, small joints, independent of bowel activity, lasts years).

• Axial disease (sacroiliitis, spondylitis) in 5 to 10%, independent of bowel activity, with HLA-B27 in 50%.

• Other extra-intestinal features: erythema nodosum, pyoderma gangrenosum, uveitis, aphthous ulcers, primary sclerosing cholangitis.

• NSAIDs may trigger IBD flares.

• Asymmetric large joint arthritis (knees, ankles) in step with colitis activity.

• Small joint symmetrical polyarthritis in type 2.

• Inflammatory back pain, enthesitis, dactylitis.

• Bowel symptoms: diarrhoea, blood, abdominal pain, weight loss.

• Clinical assessment of joints and bowel; ESR, CRP, faecal calprotectin, haemoglobin, ferritin.

• Radiographs, MRI sacroiliac joints for axial disease; ultrasound for synovitis and enthesitis.

• Colonoscopy with biopsy to establish and stage IBD if not known.

• Rheumatoid factor and anti-CCP negative; HLA-B27 supportive; joint aspiration to exclude sepsis and crystals.

• Treat the bowel disease in parallel (type 1 arthritis settles with IBD control).

• Avoid regular NSAIDs; short courses of low dose (celecoxib 200 mg daily or naproxen) only in quiescent bowel disease.

• Peripheral arthritis: sulfasalazine 1 g twice daily to 3 g daily, methotrexate 15 to 25 mg weekly, azathioprine 2 to 2.5 mg/kg; intra-articular triamcinolone; short oral prednisolone 20 to 40 mg for flares.

• Biologics that treat both: adalimumab 160/80 mg then 40 mg every 2 weeks, infliximab 5 mg/kg at weeks 0, 2, 6 then every 8 weeks, golimumab, certolizumab; ustekinumab 90 mg every 8 weeks, vedolizumab (gut selective, may not help joints); tofacitinib 5 to 10 mg twice daily and upadacitinib 15 to 30 mg for UC and spondylitis.

• Avoid IL-17 inhibitors (secukinumab, ixekizumab), which can exacerbate or trigger IBD.

• Physiotherapy; screen TB and hepatitis B before biologics.

• Multidisciplinary rheumatology and gastroenterology follow up.