Daniela Di Giuseppe, from the Karolinska Institutet, in Stockholm, and colleagues examined the effect of smoking intensity, duration, and cessation on the risk of RA using data from the Swedish Mammography Cohort, including 34,101 women (219 cases of RA) aged 54 to 89 years who were followed from 2003 through 2010.
The researchers found that the risk of RA correlated significantly with smoking intensity (one to seven cigarettes per day versus never smoking: relative risk, 2.31) and smoking duration (one to 25 years versus never smoking: relative risk, 1.60). The risk was significantly elevated even 15 years after smoking cessation, compared with never smokers (relative risk, 1.99). The risk of RA seemed to decrease with the time since stopping smoking. The risk was lower for women who stopped 15 years before the start of follow-up versus those who stopped one year before the start of follow-up (relative risk, 0.70; 95 percent confidence interval, 0.24 to 2.02).
"Our study indicated that even light smoking is associated with increased risk of RA for women. In extension to this, we showed that the risk of RA was decreasing over time after smoking cessation, but compared to never smokers the risk was still statistically significantly higher," the authors write. "The clearly increased risk of RA development even among former smokers is another reason to persuade women not to start smoking."