Association between the Chinese visceral adiposity index and thyroid nodule risk: a retrospective analysis of cross-sectional, case-control, and cohort studies

With the increasing use of ultrasound, the detection rate of thyroid nodules (TNs) has risen markedly in recent years. However, the relationship between obesity and TNs remains controversial. This study aimed to investigate the association between the Chinese visceral adiposity index (CVAI), a novel obesity indicator, and the risk of TNs. A multi-design study was conducted among individuals aged 18–80 years who underwent periodic health examinations in Suzhou, China, from 2020 to 2024. The discovery stage comprised cross-sectional and case-control analyses to examine associations between CVAI and TN risk. The validation stage involved a prospective cohort study evaluating the predictive role of CVAI in incident TNs. Multivariable logistic regression and Cox proportional hazards models were applied. The cross-sectional study included 83,757 participants, and the case-control study included 31,035 matched pairs. The median age was 40.59 and 39.28 years, respectively. Each standard deviation increase in CVAI was significantly associated with an increased risk of TN [cross-sectional: odds ratio (OR) = 1.19, 95% confidence interval (95% CI): 1.16–1.22; case-control: OR = 1.24, 95% CI: 1.20–1.27]. The cohort study including 18,110 participants validated the association [hazard ratio (HR) = 1.12, 95% CI: 1.07–1.18]. Restricted cubic spline analyses demonstrated a nonlinear dose-response relationship, with a steep rise in TN risk at higher CVAI levels. Subgroup analyses revealed stronger associations in females, individuals with lower body mass index (BMI), those who engaged in regular exercise, and participants without dyslipidemia. Elevated CVAI was significantly associated with an increased risk of TNs. These findings provided new insights for scientific management and prevention of TNs, highlighting the potential value of CVAI in health management.