New data flags need for oxygen therapy as a major PH risk factor in ILD
Study identifies key markers of PH among people with interstitial lung diseases
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Patients with interstitial lung diseases (ILDs) who require supplemental oxygen are more than three times as likely to experience pulmonary hypertension (PH), according to new interim data from the PHINDER study.
The findings reveal that this serious complication is frequently missed by doctors, who correctly identified PH in 60% of cases.
Because PH involves high blood pressure in the lung’s vessels, it can severely worsen the prognosis for those already dealing with lung scarring. The study suggests that relying on objective clinical markers rather than on clinical judgment alone is vital for detecting the condition early enough to treat it.
The study, “Screening for Pulmonary Hypertension in Interstitial Lung Disease: Preliminary Results from the PHINDER Study,” was published in Advances in Therapy.
The research was funded by United Therapeutics, the company behind Tyvaso (inhaled treprostinil), which in 2021 became the first U.S.-approved therapy specifically for PH associated with ILD (PH-ILD).
The hidden burden of PH in lung disease
ILDs are a group of lung disorders characterized by fibrosis (scarring) and inflammation. PH, defined by elevated pressure in the vessels that carry blood from the heart to the lungs, can occur in ILD and is associated with worse outcomes. This is known as PH-ILD, and while it’s well-established, it remains underrecognized. People with ILD often aren’t diagnosed with PH until they are undergoing evaluations for a potential lung transplant.
However, “challenges and delays remain in the detection of ILD and resulting PH. Currently, there are no prospectively validated strategies to aid the diagnosis of [PH-ILD],” the researchers wrote.
United is sponsoring PHINDER (NCT05776225), a clinical trial that systematically screens for PH in adults with ILD. The goal is to identify factors associated with PH in ILD, with the ultimate aim of improving the detection of this disease complication. PHINDER is still recruiting participants at dozens of sites in the U.S.
This study reported interim results from the first 190 ILD patients evaluated in PHINDER. More than half (55%) of these patients met the criteria for PH. In statistical analyses, the researchers found that ILD patients who used supplemental oxygen were more than three times as likely to be diagnosed with PH compared with patients who didn’t use oxygen.
A variety of clinical measures were also found to be predictive of PH. For example, a standardized measure of lung function, the diffusing capacity of the lung for carbon monoxide (DLCO), was found to be significantly predictive of PH risk. Various lung imaging parameters were also significantly associated with PH.
Many of the same factors that were predictive of PH in general, such as a need for supplemental oxygen and DLCO measures, were also predictive of severe PH. The researchers also noted that high levels of a heart damage marker called NT-proBNP were associated with an increased risk of severe PH, though elevated NT-proBNP was not linked to PH generally.
“Although NT-proBNP is commonly used to screen for pulmonary hypertension, particularly in earlier stages of disease, our findings suggest that its utility may be limited in detecting mild-to-moderate PH in ILD, as elevations were not consistently observed in patients with PH and were only found to be correlated with severe PH,” the researchers wrote.
Before each patient underwent diagnostic testing, their clinician predicted whether they had PH based on all available clinical data. Results showed that clinicians often got it wrong, with an overall accuracy of 60%. These data “suggest limitations in relying solely on clinical judgment,” the researchers said, emphasizing the need for more objective markers to guide PH detection in ILD.
The PHINDER study is ongoing, and once all trial data are available, the researchers hope to build on these analyses to develop new tests for PH-ILD screening.
“Additional data on the remaining PHINDER participants will look to support these findings, provide prognostic cutoff values for continuous variables, and further refine a validated, practical tool to screen for PH in ILD,” the scientists concluded.
