LAUSR

OBJECTIVE Arthritis, myositis and interstitial lung disease (ILD) constitute the classic clinical triad of anti-synthetase syndrome (ASSD). These patients experience other accompanying features, such as Raynaud's phenomenon, fever or mechanic's hands. Most ASSD patients develop the complete triad during the follow-up. In the present study we aimed to determine whether the subsequent appearance of accompanying features may suggest the development of triad findings lacking at the onset in anti-Jo1 positive ASSD patients. METHODS Anti-Jo1 positive patients presenting with incomplete ASSD (no >2 classic triad features) were assessed. Clinical characteristics and clusters of disease manifestations were retrospectively collected and analyzed in a large international multicenter cohort of ASSD patients. RESULTS 165 patients (123 women) with incomplete ASSD were identified. Ninety-five patients (57.5%) developed new classic triad manifestations after 15months median (IQR 9-51) and 40 (24%) developed new accompanying features after 19months median (IQR 6-56) from disease onset. During the follow-up, the ex-novo occurrence of triad features was observed in 32 out of 40 patients (80%) with new accompanying findings and in 63 out of 125 patients (50.5%) without new accompanying findings (p=0.002). In patients with at least one new accompanying feature the odds ratio for the occurrence of new triad manifestations was 3.94 with respect to patients not developing ex-novo accompanying findings (95% CI 1.68-9.21, p=0.002). CONCLUSION Anti-Jo1 ASSD patients with incomplete forms at disease onset are at high risk for the subsequent occurrence of lacking classic triad findings. Although all ASSD patients should be carefully assessed for the occurrence of new triad features, a closer follow-up should be considered in the subgroup of patients developing ex novo accompanying findings. These patients, indeed, have near four-fold increased risk for new classic triad manifestation occurrence with respect to patients not presenting ex novo accompanying findings.