HRR1<16 was a better predictor of clinical worsening than 6MWD alone, and when added to 6MWD improved the ability of 6MWD to predict time to clinical worsening. "HRR1<16 was also associated with known predictors of poor prognosis in IPAH," Dr. Minai added. "Patients with HRR1<16 were more likely to need supplemental oxygen during the 6MW test, be in World Health Organization functional class 4, and have more severe right ventricular dysfunction and pericardial effusion."
The study had some limitations, including its retrospective design. In addition, the time lag between right heart catheterization and the 6MW test may have biased the results, because treatment may have altered baseline hemodynamic parameters.
"HRR1 is highly predictive of clinical worsening and time to clinical worsening in patients with IPAH," concludes Dr. Minai, "and is highly correlated with known indicators of poor prognosis in these patients. Clinical worsening and time to clinical worsening have been used as end-points in a number of clinical trials in patients with IPAH. The strong predictive ability of HRR1 in these patients could make it a valuable new tool for measuring treatment response. Further study in larger prospective studies will better define its role in both IPAH and other forms of PAH."
|Contact: Nathaniel Dunford|
American Thoracic Society