Sustained smoking cessation may reduce excess RA risk
medwireNews: Maintaining a nonsmoking status for a sustained period is associated with a reduction in the excess risk for developing seropositive rheumatoid arthritis (RA), findings suggest.
Among participants of the US Nurses’ Health Study (NHS) and the NHSII, those who gave up smoking at least 30 years prior to the analysis had a significant 37% lower risk for seropositive RA than individuals who quit less than 5 years previously.
And there was a significant and inverse correlation between the duration of smoking cessation and the risk for seropositive RA, and indeed for all RA.
However, “a modestly elevated” risk for seropositive RA and all RA remained even 30 or more years after smoking cessation, with significant hazard ratios (HRs) of 1.30 and 1.25, respectively, report Jeffrey Sparks (Brigham and Women’s Hospital, Boston, Massachusetts, USA) and co-researchers.
They therefore comment: “While smoking cessation may not decrease RA risk to the level of a never smoker, our findings provide evidence that a behavior change of smoking cessation may delay or even prevent the onset of seropositive RA.
“These results could provide rationale for a smoking intervention trial among active smokers to prevent the formation of RA-related autoantibodies or to prevent the progression to RA among those at elevated risk for seropositive RA.”
The analysis included data for 117,182 NHS and 113,550 NHSII participants, of whom 1528 developed RA (63.4% seropositive) over the course of 6,037,151 person–years of follow-up. A higher proportion of NHS than NHSII participants were current (18.8 vs 13.4%) or past (35.8 vs 21.3%) smokers.
After accounting for confounders such as age, BMI, menopausal status, and alcohol intake, current and past smokers had a significantly elevated risk for RA relative to never smokers, at HRs of 1.47 and 1.36, respectively.
The risk for seropositive RA was similarly increased for current and past smokers, with respective significant HRs of 1.67 and 1.48 versus never smokers, but there was no significant association between smoking status and seronegative RA.
This lack of an association “despite [a] large sample size and lengthy follow-up,” indicates that “seropositive and seronegative RA may be distinct phenotypes with distinct risk factors,” write Sparks et al in Arthritis Care & Research.
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