Abstract
BACKGROUND: In the past decade, numerous studies have highlighted a notable correlation between the prognosis of various cancers and uric acid (UA). Nevertheless, scientific literature regarding the association between central lymph node metastasis (CLNM) and UA remains lacking. This study sought to examine the association between UA and the likelihood of CLNM in individuals with papillary thyroid cancer (PTC) and to determine the UA threshold. METHODS: Three hundred and seventy individuals with confirmed PTC who underwent surgery at the First People's Hospital of Kunshan from October 2018 to July 2024 were included in this study. Initially, UA levels were measured, and the incidence of CLNM in PTC patients was assessed through postoperative pathology. Propensity score-matched (PSM) analysis was used to match patients. Multivariate logistic regression and a two-piecewise linear regression model were utilized to analyze the relationship between UA and CLNM and identify the threshold effect of UA concentrations on CLNM. RESULTS: The correlation between UA and CLNM in PTC patients was found to be positive. Upon adjusting for various confounding factors, it was determined that, relative to the referential level, the odds ratio for CLNM was 4.01 at peak UA levels. After PSM analysis, the odds ratio for CLNM was 5.23 at the highest levels to the lowest levels. A non-linear relationship between UA and CLNM emerged following adjustment for potential confounding factors. The study identified 219.20 µmol/L as the UA threshold, serving as the optimal inflection point. The effect sizes and confidence intervals on both sides of the inflection point were -4.43 (-9.69-0.84) and 3.78 (1.70-5.85), respectively. CONCLUSION: The study concludes that the association between UA and CLNM is non-linear. A positive relationship between UA and CLNM was observed when UA levels exceeded 219.20 µmol/L.