“There has been intense interest in mucosal lung inflammation from personal smoking as a site of RA pathogenesis,” said senior author Jeffrey A. Sparks, MD. “But the majority of RA patients aren’t smokers, so we wanted to look at another inhalant that might precede RA.”
Rheumatoid arthritis is an inflammatory disease affecting many joints, including those in the hands and feet. The body’s immune system attacks its own tissue, and in severe cases, it can attack internal organs. Many people with RA have been found to have lung inflammation, and smoking has long been implicated as a key RA risk factor.
For the study, Sparks and his colleagues used NHSII questionnaires collected biennially between 1989 and 2017. All participants were women 35–52 years old who had their medical records used to confirm incident RA and seropositive (positive for RA antibodies).
Researchers found a 75 percent higher risk of RA in individuals who experienced passive childhood exposure to parental smoking. This risk increased in participants who themselves became smokers. Over the median follow-up of 27.7 years, 532 women in the cohort developed RA cases. The majority of the women were seropositive.
Smoking during pregnancy and years lived with smokers beyond the age of 18 showed no significant association with incident RA risk.
“Our findings give more depth and gravity to the negative health consequences of smoking in relation to RA, one of the most common autoimmune diseases,” said lead and co-corresponding author Kazuki Yoshida, MD, “This relationship between childhood parental smoking and adult-onset RA may go beyond rheumatology—future studies should investigate whether childhood exposure to inhalants may predispose individuals to general autoimmunity later in life.”
All Female Participant Pool
This study was limited as it was an all-female participant pool. More research is needed to confirm these findings in a population of both sexes. This research team intends to continue with studies that include both men and women to provide critical insight into joint health, rheumatoid conditions, and even other autoimmune diseases.