A NEW cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES) revealed a significant association between secondhand smoke (SHS) exposure and the risk of developing rheumatoid arthritis (RA) in never-smoking adults in the United States. The study aimed to shed light on the potential health risks posed by SHS exposure, which has been widely acknowledged as a risk factor for various diseases but is less understood in the context of RA.
The study analysed data from 14,940 adults who self-reported as never smokers, collected from NHANES between 1999 and 2018. SHS exposure was quantified using serum cotinine levels, which is a biomarker for nicotine intake. The participants were categorized into four groups based on their serum cotinine levels: unexposed (<0.05 ng/mL), low exposure (0.05 to 0.99 ng/mL), moderate exposure (1 to 10 ng/mL), and heavy exposure (≥10 ng/mL). The researchers also employed adjusted odds ratios (ORs) to examine the association between SHS exposure and RA while controlling for various covariates.
The results showed that individuals in the low exposure group (serum cotinine 0.05 to 0.99 ng/mL) had a 37% higher risk of developing RA compared to the unexposed group, with an adjusted OR of 1.37 (95% CI 1.14–1.64, p=0.001). Interestingly, no significant association was observed in the moderate (serum cotinine 1 to 10 ng/mL) or heavy exposure groups (serum cotinine ≥10 ng/mL). Additionally, a non-linear, positively saturated correlation was identified between log2-transformed cotinine levels and RA, with a turning point at approximately -2.756 ng/mL (OR=1.163, 95% CI 1.073–1.261, p=0.0002).
The results of the study showcase the potential risk of developing RA due to low levels of SHS exposure in never-smoking adults, suggesting that even minimal SHS exposure can have significant health impacts. These findings highlight the importance of public health efforts to minimize SHS exposure to reduce the risk of RA and other associated diseases.
Aleksandra Zurowska, EMJ
Reference
Qi X et al. Association between secondhand smoke exposure and rheumatoid arthritis in US never-smoking adults: a cross-sectional study from NHANES. Sci Rep. 2024;14:11061.
