Prognostic markers for systemic sclerosis.

The prognosis of systemic sclerosis depends chiefly on the extent of the skin lesions, which correlates with the severity of the cardiovascular, pulmonary, and renal manifestations. An erythrocyte sedimentation rate greater than 15-25 mm/h or a hemoglobin level lower than 12.5-11 g/dl is associated with a 2.5- to 3-fold increase in mortality. Anticentromere antibodies are associated with delayed pulmonary hypertension, anti-topoisomerase I antibodies (Scl 70) with interstitial lung disease, and anti-RNA polymerase III antibodies with renovascular hypertension. The risk of death is directly related to the autoantibody pattern. For instance, in a study of 1432 cases from the Pittsburgh Scleroderma Databank, 10-year survival among patients with limited cutaneous disease was 88% in the group with anti-U1-RNP, 75% in the group with anticentromere antibodies, 72% in the group with anti-PmScl, and 65% in the group with anti-Th/To. Ten-year survival in patients with diffuse cutaneous disease was 64% with anti-topoisomerase antibodies, 61% with anti-U3-RNP, and 75% with anti-RNA polymerase III. Several prognostic markers are also available for predicting the risk of organ involvement. For instance, serum levels of KL-6, surfactant proteins SP-A and SP-D, the collagen peptide PIIINP, and homocysteine are associated with the risk of fibrosing alveolitis. Serum levels of CD40L and NP-ProBNP, circulating endothelial cells, and serum anticardiolipin titers correlate with the risk of arterial hypertension. Serum VCAM1 and markers for oxidative stress such as carboxyl terminus residues predict the risk of vascular disease. Other serum markers for organ involvement are under study, although their predictive performance remains to be evaluated.