Progressive Massive Fibrosis Observed in Federally Funded Black Lung Clinics


These data on PMF among coal miners suggest that urgent action may need to be taken to protect these workers from the preventable disease.

Drew A. Harris, MD

Credit: CHEST Daily

Drew A. Harris, MD

Credit: CHEST Daily

There is a significant burden of progressive massive fibrosis (PMF) among coal miners, according to findings from federally-funded Black Lung Clinics, with silica dust exposure being a key risk factor.1

These results came from a recent research letter on the burden of PMF among miners, as the condition is known to be the most severe and the most disabling type of pneumoconiosis affecting coal workers.2

The research was led by Drew A. Harris, MD, from the Department of Medicine at the University of Virginia, Charlottesville. Harris and colleagues noted in their letter that the Health Resources and Services Administration in 2019 demanded patient-level information to be gathered by each of the 15 Black Lung Clinics which are federally-funded and maintained in 11 states.3

“We provide an update on the burden of PMF in coal miners served by SMHS and describe PMF cases identified at all other US Black Lung Clinics,” Harris and colleagues wrote.

Background and Findings

The investigators in this letter identified instances of PMF by classifying the condition as a pneumoconiosis, using large opacity categories A (>1 cm and ≤5 cm), B (≥5 cm though it is less than the equivalent region of the upper right lung zone), or C (greater size compared to category B) for the coal miners.

They did this based upon clinic-administered radiography which had been done between February 2017 - June 2023 or July 2019 - June 2023.

The Black Lung Data and Resource Center database had been initiated in the year 2017 for Stone Mountain Health Services (SMHS). The database was also expanded to all of the federally-funded clinics in the year 2019.

The investigators noted that the database was implemented to identify cases of PMF, and they used chart abstraction at SMHS to make sure that cases which were seen since February 2017 had not been reported previously.

The team classified chest radiographs through the use of a certified B reader, assessing small opacity profusion on a scale of 0 - 3.The University of Illinois Chicago’s institutional review board approved the study with a waiver of informed consent.
The research team looked at the shape, profusion, and the overall size of small opacities in their research. Specifically, they aimed to look at rounded opacities 3 - 10 mm (r-type) as the primary or secondary small opacity type as a result of their association with exposures to crystalline silica.

The case definition for PMF was met with 1177 total coal miners, some of which represented 651 new cases at SMHS and 526 seen at all other Black Lung Clinics. Among the workers with reported cases of PMF, the research team reported that 86% were known to be residents of the central Appalachian states of Virginia, Kentucky, or West Virginia.

The team identified the mean age of the subjects as 65 years, noting that 70 workers below the age of 50 and 79 had shown below 15 years of employment in the field of coal mining. The investigators showed that a majority of the subjects were found to have worked underground over the course of all or part of their careers (91%).

They added that a major portion were former miners (92%) based on the radiography. The team showed that among the miners, it was noted that 23% were found to have exhibited category B or C large opacities, and 62% were found to have small opacity profusion scores of category 2 or higher.

Additionally, the investigators reported that r-Type opacities had been seen in 33% of the miners.

“Currently, more than 50 000 US coal miners work at nearly 1000 mines,” they wrote. “Urgent action is needed to protect them from this preventable and debilitating disease.”


  1. Harris DA, Almberg KS, Blackley DJ, et al. Progressive Massive Fibrosis Identified at Federally Funded Black Lung Clinics in the US. JAMA. Published online January 04, 2024. doi:10.1001/jama.2023.25578.
  2. Blackley DJ, Reynolds LE, Short C, et al. Progressive massive fibrosis in coal miners from 3 clinics in Virginia. JAMA. 2018;319(5):500-501. doi:10.1001/jama.2017.18444.
  3. The Black Lung Data and Resource Center. Black Lung Center of Excellence. Accessed September 20, 2023.
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