Could Smoking Raise RA Risk?

The findings of a new study have suggested that smoking is causally associated with an increased risk of rheumatoid arthritis (RA).

In their study, the researchers used genetic predisposition to smoking to examine the link between smoking and RA risk. They performed a Mendelian randomization using summary statistics data from published genome-wide association studies (GWAS), which included 14,361 RA cases and 43,923 controls. The researchers also obtained the genetic instrumental variables related to smoking initiation (ever being a regular smoker vs never being a regular smoker) from a GWAS meta-analysis that included 1,232,091 individuals. The genetic association estimates for smoking initiation and lifetime smoking were obtained from a GWAS of 462,690 individuals.

All data were on patients of European ancestry.

Compared with never smoking, genetic predisposition to smoking was associated with a 32% increased risk of developing RA. Likewise, genetically predicted lifetime smoking was associated with a 55% increased risk of RA. 

“Sensitivity analyses using alternative [Mendelian randomization] methods and different sets of IVs produced similar results, suggesting the robustness of our findings,” the authors wrote. “Further studies are warranted to explain the underlying mechanisms of smoking in the development of RA.” 

—Colleen Murphy

Reference:

Qian Y, Zhang L, Wu DJH, Xie Z, Wen C, Mao Y. Genetic predisposition to smoking is associated with risk of rheumatoid arthritis: a Mendelian randomization study. Arthritis Res Ther. 2020;22(1):44. doi:10.1186/s13075-020-2134-1.