Does Duke Activity Status Index help predicting functional exercise capacity and long-term prognosis in patients with pulmonary hypertension?

Background: To investigate the association of Duke Activity Status Index (DASI) with 6-minute walk test (6MWT) and WHO-Functional Class (WHO-FC) in patients with pulmonary hypertension (PH), as well as exploring whether DASI can discriminate between the patients with better and worse long-term prognosis according to 400 m cut-off score in 6MWT. Methods: Eighty-five medically stable PH patients who met eligibility criteria were included. All patients were evaluated using 6MWT and DASI. The prognostic utility of the DASI was assessed using univariate linear regression and receiver operating characteristic (ROC) curve analysis. Results: The DASI was an independent predictor for both 6MWT and WHO-FC, explaining 50% of variance in 6MWT and 30% of variance in WHO-FC class (p < 0.001). In addition, DASI significantly correlated to 6MWT (r = 0.702) and WHO-FC class (r = 0.547). The ROC curve analysis revealed that the DASI had a discriminative value for identifying the patients with better long-term prognosis (p < 0.001), with an area under ROC curve of 0.867 [95% CI = 0.782-0.952]. The DASI >= 26 was the optimal cut-off value for better long-term prognosis, having sensitivity of 0.74 and a specificity of 0.88. Conclusions: The DASI is a valid tool reflecting functional exercise capacity in patients with PH. Considering its ability to discriminate between the patients with better or worse long-term prognosis, it may help identifying the patients at higher risk.