Low lifelong exposure to cigarette smoking associated with RA risk

Di Giuseppe D. Arthritis Res Ther. 2014;doi:10.1186/ar4498.

  • March 11, 2014

Lifelong cigarette smoking was associated with the risk for developing rheumatoid arthritis, with an increased risk even at a low level of exposure and a plateau at 20 pack-years, according to recent study results.

Daniela Di Giuseppe, PhD student, division of nutritional epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, and colleagues conducted a search of Medline and Embase for relevant studies published from 1966 to October 2013. A dose-response, random-effects, meta-regression analysis was conducted on studies reporting relative risks or odds ratio estimates for the association between pack-years of cigarette smoking and rheumatoid arthritis (RA).

Daniela DiGiuseppe MD 

Daniela Di Giuseppe

Three prospective cohort studies and seven case-control studies, including 4,552 RA cases, were analyzed. Heterogeneity was not indicated in the studies (P=.32), and results were not affected by publication bias. People who smoked 1 to 10 pack-years of cigarettes had a relative risk of 1.26 (95% CI, 1.14-1.39) for RA compared with never smokers, while smokers with 21 to 30 pack-years had an RR of 1.94 (95% CI, 1.65-2.27). No significantly greater risk for higher smoking exposure levels was observed.

Rheumatoid factor (RF)-positive RA cases had a significantly greater risk for RA (RR=2.47; 95% CI, 2.02-3.02) than RF-negative cases (RR=1.58; 95% CI, 1.15-2.18), when highest vs. lowest categories of pack-years for individual studies were compared.

“Our study showed some evidence of a nonlinear dose-response relationship between lifelong smoking and risk of RA,” the researchers concluded. “The risk increased already at a relatively low level of lifelong exposure to smoking [≤10 pack-years] and stabilized to approximately a double risk for a smoking exposure higher than 20 pack-years.”

Disclosure: The researchers report no relevant financial disclosures.


Healio is intended for health care provider use and all comments will be posted at the discretion of the editors. We reserve the right not to post any comments with unsolicited information about medical devices or other products. At no time will Healio be used for medical advice to patients.