Autoinflammatory & rare systemic diseases
IgG4 surge and relapse: determining the predictive threshold for IgG4 rising kinetics in IgG4-related disease
Authors' conclusion
The IgG4 surge defined as an IgG4-Ratio >1.6 (indicating a >60% increase in IgG4 levels between consecutive measurements taken at median 3-month intervals) predicts relapse in the majority of seropositive IgG4-RD patients. Intensified treatment in patients with IgG4 surge can reduce recurrence risk.
Study context
- Population
- Patients with IgG4-related disease (IgG4-RD) with >6 months of follow-up and ≥3 IgG4 measurements, Chinese PLA General Hospital, February 2016 to May 2023median follow-up 33 months
- Participants
- 155 patients
- Exposure
- IgG4 dynamics (IgG4-Ratio thresholds) vs single-timepoint IgG4 level for predicting relapse; intensified treatment after IgG4 surge
- Outcome
- Relapse predicted by IgG4-Ratio (sequential visit-to-visit fold-change) and single-timepoint IgG4 level
Methodological detailssingle-centre, time-dependent Cox regression, restricted cubic splines
- Single-centre
- Time-dependent Cox regression
- Restricted cubic splines
Main finding
As reported in the abstract
Prediction of relapse
- IgG4-Ratio thresholds >1.1-1.3 and >1.6-1.8 significantly predicted relapse
- P < 0.05
- Restricted cubic splines (RCS) nonlinear dose-response relationship
- P = 0.008
- Optimal threshold to predict relapse: IgG4-Ratio
- >1.6
Observational data: associations, not effects.
Further findings
Relapse risk with intensified treatment in patients with IgG4-Ratio >1.6 (n=45)
| HR (95% CI) | P value | ||
|---|---|---|---|
| Intensified treatmentRelapse risk reduced by 68.3% | 0.317 (0.102–0.988) | P = 0.048 | |
| 0.10.31310Hazard ratio (log scale) |
IgG4 normalization among patients with baseline IgG4 positivity (149)
- IgG4 normalized
- 63.8% (95/149)
- IgG4 re-positivity among those normalized
- 61.1% (58/95)
Original publication
IgG4 surge and relapse: determining the predictive threshold for IgG4 rising kinetics in IgG4-related disease. Rheumatology (Oxford). Published 27 February 2026. doi:10.
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