Influence of clinical features, serum antinuclear antibodies, and lung function on survival of patients with systemic sclerosis

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 ide ntified using clinical charts and study records of all new patients with SS c. Disease onset was defined as the time of onset of cutaneous sclerosis. V ital status and causes of death were determined at the end of the observati on period. Data on clinical status and pulmonary function were obtained. An titopoisomerase 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 te chnique, radioactively labelled antisense riboprobes. and ELISA. respective ly. Results. Patients were followed for a mean period of 13.3 yrs; 16 died of a n SSc related condition and 50 of other causes. Pulmonary fibrosis, DLCO re duction < 40% of the expected, diffuse cutaneous involvement. SSc nephropat hy, cardiac disease. and anti-topo I and anti-RNA-P antibody were related t o decreased survival due to SSc. Variables that entered a Cox regression mo del 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 develo ping right heart failure and diffuse SSc given the presence of anti-RNAP an tibody was 14 (p = 0.0001) and 1.9 (p = 0.01), respectively. The correspond ing 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 a nd diffuse SSc, both of which were also associated with the presence of ant i-topo I and anti-RNAP antibody. The prognostic value of these autoantibodi es may lie in the early course of the disease when specific morbidity has n ot yet evolved.