Impact of Capillaroscopy on the Management of Undifferentiated Connective Tissue Disease

Connective tissue diseases (CTD) are a group of diseases with diverse manifestations, most often multisystemic, which share an autoimmune etiology. They include Systemic lupus erythematosus (SLE), Systemic sclerosis (SSc), Sjögren's syndrome (SS), Inflammatory myopathies (IM) and Mixed connective tissue disease (MCTD). Many patients in rheumatology present signs and symptoms of CTD, but without meeting all the classification criteria for one of these diseases. These patients will generally receive a diagnosis of undifferentiated connective tissue disease (UCTD). It is increasingly suggested that there are two subgroups of patients with UCTD: one which will eventually evolve into a better characterized CTD (approximately 30% of patients at 5 years) and another with a more benign prognosis. The optimal management of patients with UCTD is not clearly established. Capillaroscopy is a diagnostic test used in the investigation of patients with CTD. It is a low-cost, non-invasive, rapid and specific test in the evaluation of this class of diseases. Its role is now well established in the diagnosis of SSc and in the investigation of Raynaud's phenomenon. In addition, capillaroscopy helps to identify patients suffering from CTD more quickly. Knowledge about the role of capillaroscopy in UCTD is more limited. It is established that a significant proportion of patients with UCTD present abnormalities on UCTD present non-specific abnormalities and 11% present a scleroderma pattern. In these patients, abnormal capillaroscopy seems to increase the risk of progressing to a better characterized CTD, notably SSc. However, although capillaroscopy is increasingly used in rheumatology in patients with CTD, more research is needed to clarify the role of this examination in UCTD. First, it is not established whether capillaroscopy should be performed in all patients with UCTD, nor when exactly it should be performed. There also remain questions about the impact of capillaroscopy on the prognosis and management of patients with this disease. To our knowledge, there is no prospective study that has addressed this question. The investigators hypothesize that in patients with UCTD, capillaroscopy compared to usual care makes it possible to increase the proportion of patients obtaining a diagnosis of better characterized CTD in the first six months of follow-up.