CURRENT VIEWS ON THE HETEROGENEITY OF RENAL INVOLVEMENTS IN PATIENTS WITH SYSTEMIC SCLEROSIS

Abstract

Systemic sclerosis (SS), is an autoimmune connective tissue disease, the main clinical signs of which are due to disseminated microcirculatory disorders and fibrosis of the skin and viscera. Morphological examinations showed that 80% of patients with SS had renal changes, including those unassociated with rheumatic diseases. Whereas the prevalence of scleroderma renal crisis is now estimated to be 2–5%, there is considerably often an asymptomatic reduction in renal function (silent uremia), which is caused by multimorbidity and comorbidity. Its incidence in patients with SS may be as high as 55%. The presence of autoimmune connective tissue disease may be itself regarded as a risk factor of renal involvement. Fifteen-year survival is 72% in SS patients with no renal involvement and not more than 13% in those having renal involvement. In patients with SS, proteinuria is one of the most important independent risk factors for fatal outcomes (relative risk, 3.34), leaving far behind canonical risk factors, such as pulmonary hypertension, restrictive lung disease (a forced expiratory volume in one second to forced vital capacity ratio of <80%), respiratory failure (NYHA Class III and IV), as well as decreased lung diffuse capacity and high skin scores. The authors first propose a concept of the existence and pathogenesis of chronic scleroderma nephropathy, the basis for which is the vascular endothelial dysfunction phenomenon developing in different structural components of the nephron and kidney as a whole.