Unravelling IPAF, VEDOSS and connective tissue diseases classifications through the mixed connective tissue disease spectrum.

Abstract

Background: Mixed connective tissue disease (MCTD) has long been debated as an early nonspecific phase/symptom of differentiated connective tissue diseases (dCTD), similarly to interstitial pneumonia with autoimmune features (IPAF) and very early diagnosis of systemic sclerosis (SSc) (VEDOSS).

Objective: We aimed to evaluate the predictive value of IPAF, VEDOSS and dCTD classification criteria variables in MCTD patients.

Methods: We conducted an observational study within the French MCTD cohort. IPAF, VEDOSS and current dCTD classification criteria were used to classify patients.

Results: Three hundred and twenty-four MCTD patients were included and followed for 8 (3.3-13) years. Among them, 111 (34.3%) progressed into a dCTD, that is, 50 (15.4%) SSc, 40 (12.3%) systemic lupus erythematosus (SLE) and 11 (3.4%) Sjögren's disease. At diagnosis, 38 (11.7%) patients fulfilled IPAF criteria, among which 15 (39.5%) progressed into a dCTD (vs 75 (26.2%) in patients who did not fulfil IPAF criteria; p=0.09). At diagnosis, 293 (90.4%) patients fulfilled VEDOSS criteria but did not progress significantly more frequently to SSc than MCTD patients without VEDOSS criteria (46 (15.7%) vs 4 (12.9%); p=0.8). At baseline, SSc classification criteria did not predict evolution toward SSc, whereas antiphospholipid antibodies and low C3 and/or C4 were predictive of an evolution toward SLE (p=0.01 and p=0.04, respectively).

Conclusion: At MCTD diagnosis, fulfilment of IPAF and/or VEDOSS criteria was not predictive of evolution toward SSc, whereas antiphospholipid antibodies and low C3 and/or C4 were predictive of an evolution toward SLE. This suggests that MCTD patients should be excluded from IPAF and VEDOSS.