Underground » Health and Safety
This project aimed to provide preliminary information on whether coal mine dust lung disease (CMDLD) tends to stay stable or progress, as observed through quantifiable measures of disease (lung function and radiology) in Queensland coal mine workers. A secondary aim was to provide evidence as to whether there is a relationship between modifiable variables (smoking status, pulmonary rehabilitation and occupational changes) and the CMDLD disease course. This project focussed on lung function and radiology and how these measures of disease changed between the point of diagnosis and later time point, once the follow up information was sufficient and available. Ultimately this research aimed to determine whether there were any measurable differences between individuals observed to have evidence of disease progression versus those that did not.
A total of 63 individuals with a CMDLD were included in this project as they had quantifiable data available at the point of diagnosis, and at a later time point (≥12 months). For the 50 individuals assessed for longitudinal changes in lung function, the mean-time interval between testing at diagnosis and the present test was 2.5 years. For the 43 individuals assessed for longitudinal changes in HRCT imaging, the mean-time interval was 3.1 years.
The research showed 18% and 21% of individuals progressed on lung function testing and radiology, respectively. 22 individuals (44%) demonstrated an average reduction in lung function considered to be abnormally high (≥60 mL/year). Similarly, when individuals were assessed across the separate ICOERD features (fibrosis, nodules, emphysema), 40% were deemed to have progressed on radiology.
These findings show a relatively large number of individuals have demonstrated progression of some kind, in the short timeframe of this project. Unfortunately, less than half (48%) of individuals were assessed for longitudinal changes in both lung function and radiology. Within this subgroup with both measures available, 11 (37%) had some form of progression (lung function and/or radiology); two (7%) individuals progressed in both lung function and radiology, two (7%) individuals progressed in lung function only, and seven (23%) individuals were observed to have signs of radiological progression only. Nineteen (63%) had both stable lung function and stable radiology.
Some key differences were observed between individuals who progressed and those who didn't, for example, individuals who progressed were more likely to have been diagnosed following retirement, to have worked in open cut coal mines, and to have smoked more cigarettes in their life. Ultimately, there was great overlap between the clinical parameters observed across outcome categories. This means there is no quantifiable parameter or modifiable lifestyle change that would assist in identifying those who might progress over those who do not, at this stage. This is not an unexpected finding, given the latent nature of CMDLD, the short lapse in time since re-identification of CMDLD, and the small number of known cases, drawing any conclusions was not anticipated to be likely, nor appropriate. Further continuation of this study, inclusive of expansion to a greater number of individuals with CMDLD and a longer time course, would further inform the disease course of CMDLD in the modern Australian setting.