- Design
- Post hoc risk-prediction model derivation from a randomised trial
- Population
- 649 PEXIVAS participants with severe ANCA vasculitis who achieved remission
- Primary outcome
- First relapse within 2 years of remission
- Effect
- Optimism-corrected C-statistic 0.709; calibration slope 0.99 (95% CI 0.65 to 1.34)
A post hoc analysis of the PEXIVAS trial in Annals of the Rheumatic Diseases (22 September 2026) built a model to predict first relapse within two years of remission in 649 patients with ANCA-associated vasculitis and either an eGFR under 50 or diffuse alveolar haemorrhage. One hundred relapsed.
The final model used sex, induction with oral cyclophosphamide or rituximab, ANCA subtype, non-haemorrhagic respiratory or mucous membrane and eye involvement at presentation, and eGFR at remission. Discrimination was moderate (C-statistic 0.71) and calibration good (slope 0.99).
The model has not been validated in another cohort and comes from a trial population with severe disease. A C-statistic of 0.71 means it ranks patients correctly about seven times in ten. It could help frame maintenance and monitoring decisions, but not yet decide them.
- Record the features that predicted relapse: sex, induction agent, ANCA type, organ involvement and eGFR at remission.
- Use relapse risk to inform the intensity of monitoring after remission.
- Do not shorten maintenance therapy on this model alone until it is externally validated.
- Explain to patients that relapse risk varies and what symptoms should prompt early review.
Why it matters
Maintenance decisions in vasculitis are mostly one-size-fits-all, and an individual risk estimate could change that.
Don't overread it
The model has not been validated outside the trial it was built in.
The statistics, in plain English
A C-statistic of 0.71 means that, given one patient who relapsed and one who did not, the model gives the higher risk to the one who relapsed about 71% of the time. A calibration slope near 1 means predicted risks matched observed risks in this data set.
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