Body mass index mediates the association between C-reactive protein-triglyceride glucose index and gallstone disease: a cross-sectional study from NHANES 2017–2020

Although the C-reactive protein-triglyceride glucose index (CTI) is recognized as a reliable biomarker for various diseases, its link to gallstone disease (GSD) has not been well characterized. This research explored the potential relationship between CTI and GSD prevalence using data from the 2017–2020 NHANES, with multivariate logistic regression and smoothed curve fitting employed. Subgroup analyses assessed consistency across demographics, and mediation analysis evaluated whether body mass index (BMI) mediated the CTI–GSD relationship. Among the 3,832 participants, CTI was significantly and positively associated with GSD. A standard deviation rise in CTI corresponded to a 22% higher likelihood of GSD (OR = 1.22; 95% CI, 1.08–1.38), while individuals in the top CTI quartile exhibited 2.18 times the risk compared to the bottom quartile (OR = 2.18; 95% CI, 1.51–3.15). This association was particularly evident in non-diabetic individuals. Mediation analysis further revealed that BMI mediated this relationship, accounting for 97.0% of the total effect. The findings reveal a significant positive link between CTI and GSD, with a stronger effect observed in individuals without diabetes. BMI was identified as a mediator in this relationship. CTI may be a practical tool for early GSD screening and preventive efforts.