People with a combination of two lung diseases — specifically pulmonary fibrosis and emphysema, known as CPFE — who also have pulmonary hypertension (PH) were found to be at an increased risk of death in comparison to CPFE patients without PH, according to a new meta-analysis.
Having CPFE also was linked to a higher risk for PH among patients than was having either lung disease alone.
While the researchers stressed that more studies were needed “to further explore the risk of PH and its impact on survival in patients with CPFE,” the findings of their meta-analysis — an analysis that combines the results of multiple scientific studies — “revealed a significantly increased risk of PH in patients with CPFE compared with those with [idiopathic pulmonary fibrosis] or emphysema alone,” they wrote.
“Also, the presence of PH was a significant predictor of mortality,” the team wrote.
Investigating the risk of PH in patients with other lung diseases
Chronic lung diseases such as chronic obstructive pulmonary disease (COPD) or idiopathic pulmonary fibrosis (IPF) can lead to the development of PH, a disorder in which the pressure in the blood vessels of the lungs, known as the pulmonary arteries, is elevated.
Such patients belong to Group 3 of the World Health Organization’s PH classifications — the most commonly used classification system for the disease. Group 3 includes individuals with PH due to lung disease or chronic oxygen shortage.
Studies have shown that patients with combined pulmonary fibrosis and emphysema, dubbed CPFE, are at a particularly high risk of developing PH.
As the name suggests, CPFE is a disease characterized by the co-existence of IPF, in which scarring and inflammation in the lungs make breathing difficult, and emphysema, where damage to the air sacs of the lungs — often due to smoking — causes breathlessness.
It is not well established whether IPF or emphysema alone confer a similar risk for PH as does the combined disease. Moreover, for CPFE patients who do have PH, it is not known whether their mortality risk is increased.
To learn more, the scientists conducted a meta-analysis of 13 previously published studies on the topic. Together, these studies involved 1,596 participants, including 560 with CPFE, 720 with IPF, and 316 with emphysema. The studies, published between 2009 and 2021, were mostly conducted in East Asia.
Patients with CPFE were more likely to be male and have a history of smoking compared with IPF patients. They also were found to have the lowest diffusing capacity of the lungs for carbon monoxide, or DLCO — a measure that assesses the lungs’ ability to transfer inhaled gas into the bloodstream.
Findings from a range of different lung function tests were consistent with the idea that CPFE patients show a mix of defects associated with either IPF or emphysema, according to the researchers.
Further study needed into risk of death for CPFE patients with PH
Patients with CPFE had a higher incidence of PH than patients with IPF alone, and were found to be at a 2.66 times higher risk of PH. Likewise, CPFE patients were at a 3.19 times higher risk relative to patients with emphysema only.
The severity of PH, reflected by an estimated measure of pulmonary artery pressure, also was higher in CPFE patients than in either group with only one lung condition. The researchers noted that the measures and cut-offs used to diagnose PH did vary between studies, limiting some head-to-head comparisons.
Scientists believe there are several reasons that might explain the risk of PH in CPFE patients. These may include blood vessel remodeling, inflammation, and blood vessel restrictions due to low oxygen levels.
“The natural course of CPFE might encompass the development of PH,” the researchers wrote. “Additional studies focusing on the molecular mechanisms of PH in patients with CPFE are urgently required in the future.”
Patients with CFPE who also had PH were found to have worse survival than patients with CFPE who did not have PH, with the risk of death more than six times higher in this population.
“Despite this dismal prognosis, there is currently no curative medication for the treatment of PH related to CPFE,” the scientists wrote. They noted, however, that the natural course of PH-CPFE, “remains to be fully explored.”
The researchers noted several issues with their analysis, most notably that there were no official diagnostic criteria for CPFE.
“Due to the limitations in this study, multi-center or prospective studies with a clear definition of CPFE should be conducted in the future,” the team wrote, noting a need to examine survival outcomes among patients.