The Association of Salivary Conductivity with Cardiomegaly in Hemodialysis Patients

Abstract

Patients on maintenance hemodialysis are at high risk for cardiovascular morbidity and mortality. Fluid overload is generally regarded as the main cause of cardiovascular death among them. Cardiothoracic ratio (CTR) by chest plain film is routinely performed to evaluate their volumetric states and cardiac conditions. We recently reported that salivary conductivity is a reliable marker for assessing fluid status in healthy adults. This cross-sectional study aims to explore the association between salivary conductivity and CTR. Cardiomegaly is defined as a CTR greater than 0.5. A total of 129 hemodialysis patients were enrolled, 42 of whom (32.6%) had cardiomegaly. Patients with cardiomegaly had significantly lower serum osmolality, lower serum sodium, and lower salivary conductivity, but a higher percentage of underlying atrial fibrillation. In the multiple linear regression analysis, CTR was negatively associated with salivary conductivity or to the serum sodium level and positively correlated with older age. We further divided patients into low, medium, and high salivary conductivity groups according to the tertials of conductivity levels. There was a significant trend for the increment of cardiomegaly from high to low salivary conductivity groups (p for trend: 0.021). The receiver operating characteristic curves for the diagnostic ability of salivary conductivity on cardiomegaly reported the area under the curve equal to 0.626 (95% CI: 0.521–0.730, p = 0.02). Moreover, older age and higher serum osmolality were independent determinants for salivary conductivity by multiple linear regression analysis. This work has presented that salivary conductivity is a novel approach to uncover fluid overload and cardiomegaly among chronic hemodialysis patients.