Spondyloarthritis
Rheumatology · Spondyloarthritis 🎯 Practice these cards
The four diseases of the spondyloarthritis family are ankylosing spondylitis, ____, reactive arthritis, and ____.
Spondyloarthritis comprises four overlapping diseases: ankylosing spondylitis, psoriatic arthritis, enteropathic (IBD-associated) arthritis, and reactive arthritis. Shared features: seronegativity (RF/anti-CCP negative), HLA-B27 association, enthesitis as the pathologic hallmark, asymmetric lower-limb oligoarthritis, dactylitis, extra-articular disease (uveitis, psoriasis, IBD), and excellent NSAID response. Cumulative prevalence 2–3% — more common than RA.
Up to ____% of white AS patients are HLA-B27 positive, yet only about ____% of HLA-B27–positive white individuals ever develop the disease.
Up to 90% of white patients with ankylosing spondylitis (and ~60% of Black patients) are HLA-B27 positive — but only ~6% of HLA-B27–positive white individuals develop disease (risk ~20% in HLA-B27–positive first-degree relatives). HLA-B27 testing is never diagnostic; it refines probability in uncertain inflammatory back pain with normal radiographs.
Inflammatory back pain improves with ____ and worsens with ____; morning stiffness lasts more than ____ minutes.
Inflammatory back pain: onset <45 years, insidious, >3 months, morning stiffness >30 min, improves with exercise and worsens with rest, second-half-of-the-night pain easing on getting up, >50% relief within 48 h of full-dose NSAIDs. Mechanical back pain is the mirror image (worse late in the day, eased by rest, stiffness <30 min). Only ~5% of chronic back pain is axial SpA.
The most common extra-articular manifestation of ankylosing spondylitis is ____, occurring in up to ____% of patients.
Acute anterior uveitis occurs in up to 27% of AS patients (~40% cumulative): episodic, unilateral, acute, with pain/redness/photophobia/miosis; typically self-limited without permanent visual loss. Recurrent uveitis (and concomitant IBD) steers biologic choice toward monoclonal TNF antibodies (adalimumab, infliximab) — etanercept does not work for eye or gut.
MRI changes meeting ASAS sacroiliitis criteria occur in ~____% of healthy individuals and up to ____% of impact-loading athletes — so MRI must be interpreted in clinical context.
MRI detects sacroiliac osteitis years before radiographs (defining nonradiographic axial SpA), but bone marrow edema meeting ASAS sacroiliitis criteria is found in ~25% of healthy individuals and up to 41% of impact-loading athletes. Extent of involvement and presence of erosions raise specificity. MRI is not used to monitor established disease.
First-line pharmacotherapy for active axial SpA is continuous full-dose ____; if disease remains active after a 4-week trial, escalate to a ____ or an ____.
Axial SpA treatment: exercise/physical therapy + smoking cessation → continuous full-dose NSAIDs (conditionally recommended over on-demand; possible disease-modifying effect unique to AS) → after a 4-week trial, TNFi or IL-17A inhibitor (screen TB/hepatitis first) → on primary failure switch class (JAKi tofacitinib/upadacitinib now also second-line per ASAS-EULAR 2022; FDA reserves JAKi for post-TNFi). csDMARDs only for peripheral disease; systemic glucocorticoids ineffective in axial disease.
IL-17 inhibitors are ____ in active IBD because IL-17 plays a ____ role in the intestinal mucosa.
IL-17 is barrier-protective in the intestinal mucosa: IL-17 inhibitors (secukinumab, ixekizumab, bimekizumab) can precipitate IBD flares and are contraindicated in active IBD. Conversely IL-23 blockade works in gut and skin but fails in the axial skeleton (entheseal γδ T cells/ILC3s make IL-17 without IL-23). TNF works in every domain; JAK inhibitors across all domains.
CASPAR criteria require inflammatory articular disease plus ≥____ points, with a specificity of ____%.
CASPAR (specificity 98.7%, sensitivity 91.4%): inflammatory articular disease (joint, spine, or entheseal) plus ≥3 points — current psoriasis (2) or personal/family history (1 each), psoriatic nail dystrophy (1), negative RF (1), current or past dactylitis (1), juxta-articular new bone formation on hand/foot radiographs (1). Nail disease is present in >80% of PsA patients.
Type 1 enteropathic peripheral arthritis ____ bowel disease activity, whereas type 2 and axial disease run a course ____ of bowel activity.
Type 1 peripheral IBD-associated arthritis: pauciarticular (<5 joints), asymmetric, lower-limb, nonerosive, parallels bowel activity. Type 2: polyarticular (≥5), symmetric, persistent, independent of bowel activity. Axial disease is always independent of bowel activity. IL-17 inhibitors contraindicated; NSAIDs avoided when possible; monoclonal TNF antibodies treat gut and joints together.
Reactive arthritis typically develops ____ to ____ weeks after genitourinary or gastrointestinal infection, and a flare usually lasts 6 weeks to ____ months.
Reactive arthritis follows 2–3 weeks after Chlamydia trachomatis (4–8% of infected; most common trigger) or enteric Salmonella/Shigella/Yersinia/Campylobacter (~1%; C. difficile 7.4%); HLA-B27 in 50–80% (90% after Yersinia). Classic triad: urethritis, conjunctivitis, arthritis; plus keratoderma blennorrhagicum, circinate balanitis, painless palatal ulcers. Course 6 weeks–6 months; ~25% chronic. Antibiotics do not alter enteric reactive arthritis (except treating active Chlamydia); NSAIDs first-line.
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