A novel U-shaped relationship between serum klotho and abdominal aortic calcification in the general population

Background: Abdominal aortic calcification (AAC) is consid-ered an independent predictor of cardiovascular morbidity and mortality. Klotho, an anti-aging gene, has cardiovas-cular protective effects. At present, the association between klotho and AAC in the general population is uncertain. We investigated the relationship between serum soluble alpha-klotho (SSKL) and AAC in 2 327 participants from the National Health and Nutrition Examination Survey. Methods: To estimate the association between log-transformed SSKL (lnSSKL) and AAC, multivariate logistic regression analyses were conducted. Stratified analyses were performed to evaluated the potential modifiers. Smoothed curve fitting and generalised additive models were also performed. Results: We found lnSSKL correlated negatively with AAC after adjusting for other confounders. The relationship of lnSSKL with AAC was a U-shaped curve (inflection point: 7.01 pg/ml). On subgroup analyses, stratified by age and smoking habit, the negative correlation of lnSSKL with AAC remained in men and in the population who smoked. Conclusion: Our study revealed a negative relationship between lnSSKL and AAC in the general population. This relationship showed a U-shaped curve and was influenced by age and smoking habit.