Several environmental exposures raise risk for sarcoidosis in African Americans

Key takeaways:

• Three environmental exposure clusters heightened the odds for sarcoidosis in African Americans.
• Environmental risk factors differed by race/ethnicity.

Exposure to mold/musty odors, various metals and farm animals raised the odds for sarcoidosis in African Americans, according to results published in Annals of the American Thoracic Society.

Further, African Americans had stronger associations between sarcoidosis risk and environmental exposures compared with European Americans, according to researchers.

“The present study adds further support to multiple exposures as risk factors for sarcoidosis identified in [A Case Control Etiologic Sarcoidosis Study] including, but not limited to, protective effects of tobacco exposure (eg, ever smoking cigarettes) and risk-increasing effects of metals and insecticides,” Albert M. Levin, PhD, director of the Center for Bioinformatics at Henry Ford Health, and colleagues wrote.

Levin and colleagues assessed 2,096 African American individuals to find out which environmental exposures are linked to a higher risk for sarcoidosis and which are linked to a protective effect against the disease.

Of the total cohort, 1,205 individuals had sarcoidosis, whereas 891 did not have this disease.

Researchers grouped 51 environmental exposures into clusters through unsupervised clustering and multiple correspondence analysis and then analyzed how the clusters and individual exposures are each linked to the risk for sarcoidosis.

Seven clusters emerged: smoke, work history, farm/outdoor animals, sources of humidity, mold/musty odors, household pets and metals.

Findings

The risk for sarcoidosis was heightened in three of the clusters (metals, farm animals and mold/musty odor), whereas exposure to two clusters (smoke and household pets) resulted in a “protective effect” against the disease.

Researchers found a significant relationship between sarcoidosis risk and 26 individual exposures.

Titanium exposure was linked to the greatest odds for sarcoidosis (OR = 9.54; 95% CI, 2.24-40.69) out of the several exposures in the metals cluster. The likelihood for this disease also went up with exposure to nickel (OR = 8.78; 95% CI, 2.67-28.83), cobalt (OR = 4.35; 95% CI, 2.03-9.35), aluminum (OR = 3.3; 95% CI, 2.23-4.9), “other metal” (OR = 2.2; 95% CI, 1.52-3.18) and insecticide (OR = 1.47; 95% CI, 1.21-1.78).

Exposure to “other farm mammals” in the farm/outdoor animals cluster raised the odds for sarcoidosis by nearly six-fold (OR = 5.99; 95% CI, 3.68-9.77), but researchers also found a protective effect against sarcoidosis with exposure to chickens and turkeys. All other exposures in this cluster (cotton/vegetable dust, farming/ranching, other raised animals) elevated the risk for the disease.

Within the mold/musty odors cluster, exposure to mold/mildew at work (OR = 1.48; 95% CI, 1.2-1.82) and musty/moldy odor at work (OR = 1.4; 95% CI, 1.17-1.68) each heightened the likelihood for sarcoidosis.

Although nearly all of the individual exposures within the household pets cluster lessened the odds for sarcoidosis in African American individuals, exposure to “other birds” increased the likelihood (OR = 1.87; 95% CI, 1.42-2.46).

Exposures differing by race/ethnicity

As an additional analysis, researchers found exposure risks in a cohort of 762 European Americans (n = 388 with sarcoidosis; n = 374 without sarcoidosis) to compare with those found for African Americans.

Between the two cohorts, 17 exposures differed by race/ethnicity, with a majority of them (15) related to sarcoidosis risk in African Americans vs. European Americans.

Rather than facing significantly higher odds for sarcoidosis with exposure to aluminum, as was seen among African Americans, European Americans had nonsignificant reduced odds (OR = 0.86; 95% CI, 0.56-1.33) for this disease.

Researchers continued to find stronger risks and protective effects in the African American cohort vs. the European American cohort when evaluating environmental exposures.

The only instance in which European Americans had a stronger protective effect against sarcoidosis compared with African Americans was in the smoke cluster when researchers looked at the link between sarcoidosis risk and exposure to other smokers in one’s home (European Americans, OR = 0.61; 95% CI, 0.43-0.86; African Americans, OR = 0.89; 95% CI, 0.73-1.09).

Notably, the risk effect of aluminum exposure was heightened with a greater percentage of genetic African ancestry in African Americans (P = .047). This dependence on genetic African ancestry was also true for fish tank exposure (within the household pets cluster), except this exposure had a protective effect.

Lastly, researchers reported that the direction of the odds ratios for sarcoidosis found in the univariate analysis stayed the same in a multivariable model that assessed 11 of the environmental exposures.

“In trying to understand the underlying causes of exposure effects that differ by race, one cannot overlook the potential of racial bias in the diagnostic workup of sarcoidosis cases and even in the exposure assessment that could lead to spurious results,” Levin and colleagues wrote. “Reports of disparate disease outcomes for low-income African Americans support this possibility, and future studies should be appropriately designed to minimize or eliminate such biases and explore measures of structural racism as potential contributory exposures to the differences in risk of sarcoidosis between African Americans and European Americans.”