Abstract
OBJECTIVE: To evaluate the independent contribution of several clinical and laboratory variables to the mortality of a cohort of Danish patients with systemic sclerosis (SSc). METHODS: A cohort of 174 patients with incident SSc was retrospectively identified using clinical charts and study records of all new patients with SSc. Disease onset was defined as the time of onset of cutaneous sclerosis. Vital status and causes of death were determined at the end of the observation period. Data on clinical status and pulmonary function were obtained. Antitopoisomerase I (anti-topo I), anticentromere, anti-U1-RNP, anti-U3-RNP, anti-Th-RNP, and anti-RNA polymerase (anti-RNAP) antibodies were determined by means of double immunodiffusion, immunofluorescence, hemagglutination technique, radioactively labelled antisense riboprobes, and ELISA, respectively. RESULTS: Patients were followed for a mean period of 13.3 yrs; 16 died of an SSc related condition and 50 of other causes. Pulmonary fibrosis, DLCO reduction < 40% of the expected, diffuse cutaneous involvement, SSc nephropathy, cardiac disease, and anti-topo I and anti-RNAP antibody were related to decreased survival due to SSc. Variables that entered a Cox regression model of SSc related mortality were right heart failure (RR 12.4, 95% CI 2.5-60), diffuse SSc (RR 7.8, 95% CI 1.8-35), SSc nephropathy (RR 6.1, 95% CI 1.8-21), and DLCO < 40% (RR 4.8, 95% CI 1.1-20). The relative risk of developing right heart failure and diffuse SSc given the presence of anti-RNAP antibody was 14 (p = 0.0001) and 1.9 (p = 0.01), respectively. The corresponding figures for anti-topo I antibody were 4.6 (p = 0.02) and 2.0 (p = 0.01). CONCLUSION: SSc related mortality was associated with right heart failure and diffuse SSc, both of which were also associated with the presence of anti-topo I and anti-RNAP antibody. The prognostic value of these autoantibodies may lie in the early course of the disease when specific morbidity has not yet evolved.
