PARIS — Wegener's granulomatosis does not appear to be triggered by occupational exposure to inhaled allergens.
The hypothesis received no persuasive support from an interim analysis of a large Swedish case-control study, Dr. Ann Knight said at the annual European Congress of Rheumatology.
She reported on 2,288 Swedish patients with Wegener's granulomatosis enrolled in a national registry between 1978 and 2003. Ten controls were matched for each patient. The risk of Wegener's was then determined for patients and controls engaged in 33 occupations involving heavy exposure to dust and 5 occupations involving exposure to animals.
The overall relative risk of Wegener's granulomatosis associated with jobs involving exposure to dust was 1.1, essentially neutral.
Among the jobs were furnace worker, stone mason, smelter, paper factory worker, wood workers, glass and ceramic worker, saw operator, and flour miller.
Two occupations actually were associated with a modestly increased rate of Wegener's: miner, with a 1.9-fold relative risk, and baker, at 1.6-fold. But the numbers of subjects involved in those occupations were small, the associations weak, and the results most likely due to the play of chance, according to Dr. Knight of Uppsala (Sweden) University Hospital.
Jobs involving exposure to animals and their dander, including farmer and veterinarian, were also associated with an insignificant combined 1.1-fold relative risk of Wegener's.
Dr. Knight explained in an interview that she decided to look at occupational inhaled allergens as a potential factor in the etiology of Wegener's because the first manifestation of the disease is often in the upper airway.
Also, an earlier case-control study by Dr. Suzanne E. Lane and coworkers at Norfolk and Norwich (England) University Hospital found significantly increased risk of Wegener's granulomatosis in farmers, individuals with high occupational exposure to silica and solvents, and those with drug or other allergies (Arthritis Rheum. 2003;48:814–23). However, this study involved just 47 Wegener's patients. The Swedish study is 50 times bigger, Dr. Knight noted.