Predicting Mortality in Patients With Sarcoidosis Awaiting Lung Transplantation

Abstract

To identify factors associated with mortality in patients with sarcoidosis listed for lung transplantation, and to create a model for predicting intermediate-term mortality in these individuals. Retrospective cohort study of patients with sarcoidosis listed for lung transplant in the United States between 1995 and 2000. After identifying important risk factors for death, we developed a mortality prediction model based on an inception cohort of 75% of the subjects. The remaining 25% of the individuals served as a validation cohort for determining the validity of the model. All patients with sarcoidosis in the United States irrespective of referral center listed for lung transplantation between 1995 and 2000. Adequate follow-up data were available for 405 patients, and 111 patients (27.4%) died while awaiting lung transplantation. Neither patient age nor gender correlated with mortality. Survivors and nonsurvivors did not differ based on the results of spirometric testing. African Americans faced a significantly increased risk of death, which persisted after controlling for other confounders (odds ratio, 2.5). The amount of supplemental oxygen used and the mean pulmonary artery pressure were the only other variables predictive of mortality. The mean (+/- SD) pulmonary artery pressure in those who survived was 31.7 +/- 11.5 mm Hg, compared to 41.4 +/- 14.4 mm Hg in nonsurvivors (p < 0.01). Survivors required 2.2 +/- 2.0 L/min of oxygen vs 2.9 +/- 1.7 L/min in those who died awaiting transplant (p < 0.01). Differences in pulmonary artery pressures did not reflect differences in cardiac status, as the pulmonary capillary wedge pressure and the cardiac index were similar in survivors and nonsurvivors. The final mortality prediction model included three variables: race, amount of supplemental oxygen needed, and mean pulmonary artery pressure. Based on the validation cohort, the concordance of the model for death within 2 years of listing was 0.61 (95% confidence interval, 0.47 to 0.76), indicating only moderate explanatory power. Race, pulmonary hypertension, and oxygen use are important factors indicative of mortality in this population. Specific guidelines for determining time of referral for transplantation in advanced sarcoidosis should be developed. Recommendations extrapolated from data for other types of interstitial lung disease may not be applicable in sarcoidosis. The independent effect of race on outcome is troubling.