Race, type of lung disease influence pulmonary sarcoidosis progression
Being Black, having restrictive lung disease predicted faster declines
Being Black or having restrictive lung disease, where it’s hard to take in enough air in a breath, were factors that predicted faster lung function declines in people with pulmonary sarcoidosis in a recent U.S. study.
“This study can inform future prospective studies to further explore pulmonary function phenotypes [profiles] of sarcoidosis and the determinants of racial differences in pulmonary function over time in sarcoidosis,” the researchers wrote in “Pulmonary sarcoidosis: differences in lung function change over time,” which was published in Thorax.
In sarcoidosis, clumps of inflammatory cells called granulomas build up in tissue. Pulmonary sarcoidosis, where these granulomas are in the lungs, is the most common manifestation. Symptoms include shortness of breath, cough, and wheezing.
The clinical picture of pulmonary sarcoidosis can be highly variable, with some patients having minimal symptoms that remain stable and others progressing to more serious complications such as lung scarring and inflammation.
While about half of sarcoidosis patients will develop progressive disease that requires more intensive long-term follow-up, there’s no good way to predict who will take the more severe course, leading scientists from Johns Hopkins School of Medicine in Maryland to retrospectively examine changes in lung function over three years in 291 people with pulmonary sarcoidosis to look for factors that might predict disease progression.
Of the participants, 46% were white and 54% were Black. Most (59%) were women and had involvement of two or more organs (61%). About two-thirds used immunosuppressant treatments at some point.
Contributors to rapid lung function decline
Lung function was monitored with three different metrics — forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and a lung diffusion test (DLCO). FVC is the maximum amount of air that can be exhaled after a deep breath, while FEV1 is the maximum air exhaled in the first second after a breath. DLCO looks at how well the lungs are transferring gas from exhaled air into the bloodstream.
Based on their initial test performance, the patients were divided into lung function profiles. With restrictive lung disease, it’s hard to fully fill the lungs with air, while in obstructive disease it’s difficult to exhale all the air from the lungs. Some patients had a combination of those profiles, others had normal lung function, and others were found to have only an isolated gas transfer defect.
Patients with restrictive lung disease exhibited faster declines in lung function, assessed via FVC and FEV1, over three years compared with those with normal lung function. No differences were observed in the other groups.
“Further work is needed to understand whether pulmonary function [profiles] can be used to inform management strategies to prevent progression of disease,” the researchers wrote.
Black patients had worse lung function at the study’s start across all three lung function measures and had faster rates of decline relative to white patients over time.
Demographic differences in environmental exposures, such as air pollution, and healthcare access disparities could inform these racial differences in part, according to the authors. No sex differences were observed.
Among the 25% of patients with the greatest predicted declines in lung function, there was a higher proportion of Black patients and restrictive or combined restrictive/obstructive lung function compared to the other 75% of patients. There remains a need to better understand what other factors contribute to more rapid lung function declines in that subset of people, the researchers said.
“Potential drivers include challenges in access to medications, difficulty with medication adherence, as well as environmental factors,” they wrote. “Understanding this group of patients could potentially highlight a high-risk group of patients for whom more targeted intervention may be beneficial.”
While the study offers insights into the factors that contribute to pulmonary sarcoidosis, future prospective studies could better establish these factors and generalize the results to larger patient populations, the researchers said.
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