Passive Smoke Exposure and Rheumatoid Risk Save

A current report in Arthritis & Rheumatology examined the Nurses Health Study II data set and shows that parental smoking, and passive exposure to children, can later lead to an increased risk of adult-onset incident seropositive rheumatoid arthritis (RA).

The Nurses’ Health Study II is a prospective cohort that collects serial health information via biennial questionnaires. They sought to see if correlations exist between maternal smoking during pregnancy (in utero exposure), childhood parental smoke exposure, years lived with smokers since age 18 and the risk of of incident RA and serologic status.

From 90,923 women, they found 532 incident RA cases (66% seropositive) with 27.7 years of follow-up.

Maternal smoking during pregnancy was associated with an increase in subsequent RA risk after confounding adjustment (HR 1.25 [95% CI 1.03, 1.52]), but not after accounting for subsequent smoking exposures.

Similary, childhood exposure to parental smoking was associated with seropositive RA after adjusting for confounders (HR 1.41 [95% CI 1.08, 1.83]), including a higher risk of seropositive RA (HR 1.75 [95% CI 1.03, 2.98]) after controlling for adult personal smoking. The effect was even greater amonst ever smokers (HR 2.18 [95% CI 1.23, 3.88]).

No significant association was seen with adult (after age 18 yrs) passive smoking with later RA (20+ years lived smoker: HR 1.30 [95% CI 0.97, 1.74] vs. none).

The authors conclude, "These findings suggest that early-life inhaled exposures such as passive cigarette smoking could predispose individuals to develop RA not explained by later personal smoking behaviors."

These findings are supported by the recent French study (EULAR 2021 abstract) showing that  passive exposure to smoking during childhood (and adulthood) increased the risk of incident RA. The association was principally observed among never smoking women.