Association between secondhand smoke exposure and hyperuricemia among never smokers: A cross-sectional analysis of...

Secondhand smoke (SHS) exposure is recognized as an important contributor to multiple adverse health outcomes, including hyperuricemia. However, the association between SHS exposure and hyperuricemia remains inconclusive. This study aimed to examine the relationship between SHS exposure and hyperuricemia using serum cotinine concentration as an objective biomarker.

Data were obtained from the National Health and Nutrition Examination Survey (NHANES) collected between 1999 and 2020. A cross-sectional analysis was performed among 18610 adults who self-reported never smoking (never smokers). Participants were categorized into four groups based on serum cotinine concentrations: non-exposure (<0.05 ng/mL), low-exposure (0.05-0.99 ng/mL), moderate-exposure (1-10 ng/mL), and heavy-exposure (>10 ng/mL). Associations between SHS exposure and hyperuricemia were evaluated using multivariable logistic regression analysis models and smooth curve fitting.

After adjusting for potential confounders, the adjusted odds ratios (AOR) for hyperuricemia in the low-, moderate-, and heavy-exposure groups, compared with the non-exposure group, were 1.34 (95% CI: 1.18-1.53), 1.48 (95% CI: 1.08-2.02), and 1.97 (95% CI: 1.27-3.05), respectively. A non-linear positive saturation association was observed between log2-transformed serum cotinine concentrations and the prevalence of hyperuricemia. The inflection point was identified at approximately -3.37 ng/mL, with an AOR of 1.15 (95% CI: 1.08-1.22). Subgroup analysis revealed consistent associations across all demographic and clinical stratifications.

Among never smokers, SHS exposure was significantly associated with an increased risk of hyperuricemia. A threshold effect was identified at a serum cotinine concentration of -3.37 ng/mL. These findings provide a direction for further study on the relationship between SHS exposure and hyperuricemia.