Six-Minute Walk Test as a Predictor of Diagnosis, Disease Severity, and Clinical Outcomes in Scleroderma-Associated Pulmonary Hypertension: The DIBOSA Study

Background Pulmonary hypertension (PH) is a common complication of scleroderma (SSc) and is a leading cause of morbidity and mortality. Objectives To explore the utility of the 6MWT in the prediction of SSc-PH and to assess its prognostic implications. Methods A retrospective review of SSc patients from 2003 to 2013, with 6MWT and echocardiogram (n = 286), was conducted. Presence of PH was defined by right heart catheterization. Patients were randomized into development and validation cohorts. Using regression techniques, we developed a scoring system to predict the presence of SSc-PH and tested it in our validation cohort. Trends of mortality and disease severity were studied for incremental scores. Results The DIBOSA scoring system includes DIstance walked in 6 min, BOrg dyspnea index, and SAturation of oxygen at 6 min. The DIBOSA score in the development cohort ranged from 0 to 3, resulting in an area of 0.858 (P < 0.0001) under the ROC curve. A score of 0 had a NPV of 100% and a score of 3 had a PPV of 86.58%. The validation cohort had an area under the ROC curve of 0.842. The DIBOSA score correlated with both pulmonary artery pressures and mortality. The 3-year survival rates for DIBOSA scores of 0, 1, 2, and 3 were 100, 100, 87.67, and 66.67%, respectively (HR = 3.92, P < 0.0001). Conclusions DIBOSA score is a sensitive tool for the prediction of SSc-PH. The DIBOSA score is a direct predictor of mortality in SSc-PH and strongly correlates with pulmonary pressures. 6MWT can be used to predict clinical outcomes in SSc-PH.