One-third of rheumatoid arthritis cases in Appalachia — as well as 20% of arthritis diagnoses overall — among men aged 50 years and older are attributable to coal mining work, according to recent data in Arthritis Care & Research.
“Multiple independent studies have found that occupational exposure to mineral dust is strongly associated with rheumatologic disease risk,” Gabriela Schmajuk, MD, of the University of California, San Francisco, and colleagues wrote. “Rheumatoid arthritis has been the condition most strongly implicated in mineral dust inhalation. The role that coal and silica dust inhalation may play in the colocation of U.S. regions in which coal mining is concentrated and where there is a high prevalence of arthritis in males is not clear.”
To analyze the link between RA and work-related exposure to coal and silica in mining regions, Schmajuk and colleague conducted a random-digit-dial telephone survey in selected counties in Appalachia. The researchers limited their research to English-speaking men aged 50 years and older with any employment history, living in mining regions of Kentucky, Ohio, Pennsylvania, Tennessee, Virginia and West Virginia, where workers demonstrated higher levels of pneumoconiosis mortality.
One-third of RA cases in Appalachia among men aged 50 years and older are attributable to coal mining work, according to data.
The 10-minute telephone interviews assessed employment, smoking history and sociodemographic information, as well as arthritis diagnoses and treatment. The researchers made 30,448 call attempts, making 7,710 contacts with potential participants, of whom 3,704 were excluded for age, sex, language or residence. An additional 3,003 refused to participate, while 30 reported no work history, leaving a total sample size of 973 participants. The researchers used multivariable logistic regression analysis to calculate odds ratios and associated population attributable fraction estimates.
According to the researchers, 27% of the included participants reported a history of coal mining work, with 19% stating they had other work-related silica exposure. In addition, 53% said they had been diagnosed with any arthritis, with 12% meeting the criteria for RA. After adjusting for covariates, the Schmajuk and colleagues found that coal mining was associated with a higher likelihood of RA (OR = 3.6; 95% CI, 2.1-6.2), with a population attributable fraction estimate of 33% (95% CI, 26-40).
Coal mining work was also associated with elevated levels of any arthritis (OR = 2.3; 95% CI, 1.6-3.2), with a population attributable fraction estimate of 20% (95% CI, 14-25).
“Our findings of increased odds ratios for arthritis and RA among coal miners in Appalachia are robust, unlikely explained by biased reporting or confounding, and are consistent with other studies, primarily of silica exposure outside of coal mining,” Schmajuk and colleagues wrote.
“Given that treatment guidelines for RA indicate that a disease-modifying agent should be initiated soon after onset of disease, earlier disease detection could be achieved through targeted surveillance among current and former coal miners,” they added. “However, the results reported here suggest that primary prevention of arthritis due to workplace protections for dust inhalation may reduce the prevalence of arthritis in general and RA in particular in the first place.” – by Jason Laday
Disclosure: Schmajuk reports no relevant financial disclosures. Please see the study for all other relevant financial disclosures.