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Twin cohort study: Smoking duration increased risk for RA after 20 years
Smoking duration increased the risk for rheumatoid arthritis twofold after 20 years of smoking, according to a recently published cohort study of twins.
Anders J. Svendsen, MD, PhD, at the Institute of Public Health at the University of Southern Denmark, and colleagues identified 157 cases of rheumatoid arthritis in a cohort of 45,280 twins born between 1920 and 1982. Researchers obtained smoking information by questionnaire and interview and estimated incidence ratios with age, sex, smoking duration and smoking intensity.
Researchers found the annual incidence of chronic persistent RA in the cohort was 18.8 per 100,000 person-years, with a rate of 25.2 for females and 12 for males. The incidence rate ratio was 1.96 among smokers, 1.93 after 30 pack-years and 1.034 per year of smoking. – by Will Offit
Disclosures: The researchers report support by the Danish Rheumatism Association.