Amount of normal lung volume linked to PH prognosis in study

Percent lung volume is ‘significant independent prognostic factor'

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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The amount of normal-looking lung tissue visible on CT scans of the chest can help to predict survival outcomes and response to treatment in people with pulmonary hypertension (PH), a study found.

The study, “Significance of normal lung volume on quantitative computed tomography analysis in Group 1 and Group 3 pulmonary hypertension,” was published in CHEST Pulmonary.

PH refers to high pressure in the vessels that carry blood through the lungs. The study looked at two types of PH: group 1 PH, also known as pulmonary arterial hypertension (PAH), and group 3 PH, which is when PH develops in someone who has an underlying lung disorder like chronic obstructive pulmonary disease (COPD).

Despite recent progress in treatments for PAH, including pulmonary vasodilators (medications that work to lower blood pressure by widening blood vessels), people with group 3 PH typically do not benefit from the same types of therapy. Prognosis can also be difficult to predict in these PH groups, with factors such as the extent of lung disease and of lung function impairment playing key roles.

Scientists in Japan conducted an analysis to see if data obtained from CT scans imaging patients’ lungs might help predict patient outcomes.

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Possible indicator of treatment response

The researchers specifically focused on a calculation called percent normal lung volume (%NLV), an indicator of how much of a patient’s lung tissue looks normal, as opposed to showing signs of disease, on an imaging scan.

In statistical analyses of data from 157 PH patients, the researchers found that individuals with a %NLV of 83.2% or higher had significantly better survival outcomes than those with lower %NLV. For example, based on this cutoff, the five-year survival rate was 81.7% for patients with a high %NLV, compared with just 36.6% for those with a lower %NLV.

“%NLV was identified as a significant independent prognostic factor in patients with PH,” the researchers concluded, adding that the data suggest “that even a relatively small reduction in %NLV has a significant impact on the prognosis of patients with PH.” The team noted that the results are consistent with those of the ASPIRE registry.

A subanalysis of patients with available data indicated that individuals with higher %NLV also tended to have a better response to treatment with vasodilators. This suggests that “%NLV might be a useful predictor of response to pulmonary vasodilators in patients with PH,” the researchers wrote.

Findings also showed that %NLV tended to vary by PH type: in general, individuals with group 1 PH had higher %NLV than those with group 3. This indicates that measuring %NLV “potentially could be useful to distinguish between groups 1 and 3 PH,” the scientists wrote.

They noted that the study was limited to analyses of patients at a single institution, highlighting a need for additional research to validate these findings.

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