Sept. 28, 2007 -- Farmers and teachers have an increased risk of dying from autoimmune diseases, but waitresses, bookkeepers, and teachers’ aides do not, new research shows.
In the largest study ever to examine the occupations of people who die from systemic autoimmune diseases like rheumatoid arthritis, scleroderma, and lupus, researchers reviewed death certificates from the mid-1980s to the late 1990s.
More than 300,000 death certificates from 26 states were reviewed, including 50,000 deaths due to systemic autoimmune disease.
The findings do not prove a link between any single occupation and autoimmune disease. But they do offer intriguing clues that could serve as a jumping off point for future research, researcher Laura Gold tells WebMD.
In farming, for example, the increase in risk was seen among farmers who worked primarily with crops, but not among those worked mostly with livestock.
“We can’t explain this,” she says. “We really need to look at questions like this more closely in future studies that include more detailed occupational history.”
Occupation and Autoimmune Disease
More than 8 million Americans are believed to have autoimmune diseases, a catchall term for some 40 different conditions. The common link between diseases like rheumatoid arthritis, scleroderma, lupus, multiple sclerosis, and Crohn’s disease is that the body attacks its own cells.
The causes of this are largely unknown, but genetic, infectious, and environmental influences are all believed to play some role. And the incidence of most autoimmune diseases is much higher among women than men.
Systemic autoimmune diseases like rheumatoid arthritis, lupus, and scleroderma, involve multiple organs.
Previous studies have suggested a link between some systemic autoimmune diseases and certain occupations, including farming and teaching.
In the newly published study, farmers and secondary school teachers were each found to have a 30% increased risk for dying from systemic autoimmune diseases.
Bank tellers, special education teachers, and mining machine operators were among those also at increased risk.
Firefighters had twice the risk of death from scleroderma compared with other occupations, but their overall risk of dying from systemic autoimmune diseases was not increased.
Younger age, being female, and being African-American were all associated with a greater risk of dying of lupus, and white race and male sex were associated with a greater likelihood of dying from rheumatoid arthritis.
While some occupations involving exposure to the public -- such as teaching and nursing -- were associated with an increased risk of dying from a systemic autoimmune disease, others -- such as restaurant server and child care worker -- were not.
Support for Environmental Role
The increases in risk for most occupations were modest, with no single job showing a dramatic increase in risk for death from systemic autoimmune disease.
Rheumatologist Michael Lockshin, MD, questions the use of death certificates as a method for tracking autoimmune disease incidence.
“Most of these diseases are not highly lethal or death is often attributed to other causes,” he says.
But he agrees the study adds support to the idea that environmental exposures play a role in diseases like rheumatoid arthritis, lupus, and scleroderma.
Lockshin is a professor of medicine and ob-gyn at Weill-Cornell Medical College in New York City.
“The hope is that if we understand the steps necessary to cause these illnesses we may be able to influence these steps,” he says