Spondyloarthritis & psoriatic arthritis
Elevated serum immunoglobulin A predicts extra-articular manifestations in axial spondyloarthritis
Authors' conclusion
Elevated serum IgA delineates an intestinally biased, extra-articular-prone axSpA phenotype and provides actionable information beyond CRP
Study context
- Population
- Patients with axial spondyloarthritis (axSpA)
- Participants
- 402 patients
- Exposure
- Elevated serum immunoglobulin A (IgA) vs non-elevated IgA
- Outcome
- Association of elevated serum IgA (>4.0 g/L) with EAMs
Methodological detailslogistic regression, Kaplan-Meier and Cox models, decision-curve analysis
- Logistic regression
- Kaplan-Meier and Cox models
- Decision-curve analysis
Main finding
As reported in the abstract
Elevated IgA by EAM status
Odds ratio (95% CI)P value
Multiple EAMsvs Without EAM
5.57(2.41–12.89)
P < 0.001Multiple EAMsvs Single EAM
3.98(1.66–9.54)
- Elevated IgA overall
- 15.0%
- ≥1 EAM during follow-up
- 45.5%
- ≥2 extra-articular manifestations (EAMs) during follow-up
- 8.7%
Observational data: associations, not effects.
Further findings
Incident EAMs (Cox model)
| HR (95% CI) | P value | ||
|---|---|---|---|
| Elevated IgAIndependent predictor | 2.28 (1.18–4.40) | P = 0.014 | |
| 0.20.5125Hazard ratio (log scale) |
| Outcome | Values | P value |
|---|---|---|
| Diagnostic performance of elevated IgA for ≥2 EAMs | Elevated IgA sensitivity 40.6% · specificity 89.0% · AUC 0.65 · Elevated IgA + CRP AUC 0.78 | |
| Crohn's diseaseElevated IgA vs Non-elevated IgA | Elevated IgA 33.3% · Non-elevated IgA 11.4% | P < 0.0001 |
EAM-free survival (Kaplan-Meier)
- Reduced EAM-free survival with elevated IgA
- P = 0.008
Decision-curve analysis
- Positive net benefit
Original publication
Elevated serum immunoglobulin A predicts extra-articular manifestations in axial spondyloarthritis. Scand J Rheumatol. Published 1 July 2026. doi:10.
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