Background Undifferentiated Connective Tissue Disease (UCTD) comprises an entity in which patients present with clinical and serologic features of Systemic Rheumatic Disease (SRD) but lack of enough criteria for diagnosing any defined SRD; this entity may remain as UCTD, evolve into a defined SRD or even regress. Preliminary definition criteria have been proposed: 1) clinical or serologic abnormalities of SRD without fulfilling established criteria; 2) positive antinuclear antibodies (ANA); and 3) disease duration of at least 3 years. Progression to a defined SRD may occur in as much as 30% of patients within five to ten years from disease onset; they predominantly evolve into Systemic Lupus Erythematosus (SLE), but also Systemic Sclerosis (SSc), Mixed Connective Tissue Disease (MCTD), systemic vasculitis, myositis and Rheumatoid Arthritis. Some patients show changes in their nailfold capillaroscopy pattern (NFCP), and a possible predictive value of this fact has been determined.
Objectives 1) To describe the evolution of a cohort of UCTD patients with at least 5 years of follow-up. 2) To establish clinical and laboratory features and NFCP associated with an increased risk of progression to a defined SRD.
Methods Patients with non defined SRD and first nailfold capillaroscopy performed between 1999-2008 who met at least 2 of the following: 1) Raynaud's phenomenon (RP), 2) ANA ≥1/80 and/or positive extractable nuclear antigens (ENA), 3) pathological NFCP, were included. Nailfold capillaroscopies were performed by the same observer with a Leica 10x23 10447123 handheld lighted microscope. Patients with defined SRD at disease onset, including Prescleroderma (PSSc), and/or less than 5 years of follow-up were excluded. Logistic regression analysis was performed to study the association between outcome and the presence of several features at disease onset: RP, arthralgias, sicca syndrome, skin and esophageal abnormalities, low complement, gammaglobulins and hematologic disorders, ANA titer and pattern, ENA, anti-dsDNA and antiphospholipid (APL) antibodies, rheumatoid factor, and NFCP.
Results Among 223 patients included, 97 had a defined SRD at disease onset and 28 had less than 5 years of follow-up. Among 98 patients analyzed, 97 (99%) were women with a mean age at disease onset of 42 years (s: ±15.8); 89 (91%) had RP, 87 (89%) ANA ≥1/80, 39 (40%) positive ENA, and 43 (44%) pathological NFCP. 61 (62%) remained as UCTD, 23 (24%) evolved into remission and 14 (14%) into defined SRD: 8 SLE, 4 PSSc, 1 MCTD, and 1 overlap syndrome. NFCP progression was observed in 31% of the subset of patients with a second nailfold capillaroscopy performed 5 years after disease onset (78/98). Significant differences between outcome and the presence of ENA (p:0.08) and APL antibodies (p:0.032) were observed; leukopenia did not reach statistical significance (p:0.059). Significant association was demonstrated for ANA titer >1/320 (OR:11.9 [1.50-94.67], p:0.02), and for pathological NFCP when comparing by pairs: remission-defined SRD (21 vs 29%, p:0.01) and remission-UCTD (21 vs 31%, p:0.03).
Conclusions 14% of patients evolved into defined SRD. ANA titer >1/320 and pathological NFCP at disease onset were associated with increased risk of progression to a defined SRD.
Disclosure of Interest None declared