Prediction of survival in progressive systemic sclerosis by multivariate analysis of clinical features.

The records of 64 patients with progressive systemic sclerosis (PSS) were reviewed. More than 100 items from the patient's history, physical examination, and laboratory tests were encoded. A two-tailed Gehan's test was used to evaluate the effect of each variable on patient survival. Variables significant at the 0.05 level were then analyzed simultaneously, using the Cox regression model, in order to determine which clinical features are most predictive of survival in PSS. By Cox regression, the presence of an S3 gallop and advanced age at onset of PSS related negatively to survival. The relative risk of death for a patient with an S3 gallop was 5.44 (ratio of risk) times that for a patient without an S3 gallop, and the risk of death for a 70-year-old patient at disease onset was 20 times that of a 20-year-old patient at disease onset. In addition, when patient selection was taken into account, corticosteroid administration had a significant effect, and seemed to actually shorten survival. Although one of the factors, age at onset, is not modifiable, the presence of either variable should alert the clinician to the patient being at high risk for short survival. The application of this technique should also prove helpful in analyzing the efficacy of various proposed therapies.