Smoking identified as a risk factor for ANCA-associated vasculitis
medwireNews: Current and former cigarette smoking is strongly associated with an increased risk for antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), researchers report.
“These findings expand the list of potential risk factors for AAV, including genetics and silica exposure,” Zachary Wallace (Massachusetts General Hospital, Boston, USA) and colleagues write in JAMA Internal Medicine.
The case–control study included 473 individuals with AAV and 1419 non-AAV controls matched for sex, race, and age. Participants were aged an average of 59 years, 59% were women, and the majority (65%) of people with AAV had myeloperoxidase (MPO)-ANCA-positive disease.
Wallace and team found that a significantly higher proportion of people with versus without AAV had ever smoked, at 54% versus 42% and an odds ratio (OR) of 1.72. The risk for AAV was higher among current than former smokers, with corresponding ORs of 2.70 and 1.58 relative to never smokers.
The researchers say that there was “a strong dose-response relationship” between cigarette smoking and AAV risk, with increasing pack–years of exposure linked to increasing odds of having the disease. Individuals in the highest category for cigarette exposure (≥60 pack–years) had the greatest elevation in risk for AAV relative to nonsmokers, with a significant OR of 30.3.
When people with AAV were categorized according to ANCA type, smoking was significantly associated with MPO-ANCA-positive AAV risk, with an OR of 3.5 for current smokers and 1.7 for former smokers relative to nonsmokers. The investigators observed “a similar trend” for proteinase 3-ANCA-positive disease, but the association did not reach statistical significance.
Wallace et al note that their findings were consistent “across subgroups of patients with certain AAV manifestations, including renal, head/neck, and pulmonary disease,” and “remained robust in multiple sensitivity analyses” accounting for factors including education status and date of diagnosis.
“The association between AAV and cigarette smoking identifies a modifiable risk factor for AAV and may suggest a possible pathogenic mechanism between respiratory exposures and development of AAV,” write the study authors.
They conclude that “[f]uture studies will be needed to understand whether smoking is associated with certain disease manifestations in AAV,” and “to examine the association between smoking status and AAV disease progression.”
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