## 3 Results
### The Prediction of Cardiothoracic Ratio  
A multiple linear regression analysis was conducted to predict the CTR from clinical parameters. Adjusted variables in regression model 1 included age, blood urea nitrogen, creatinine, salivary conductivity, glucose, and serum sodium and potassium levels. Only older age  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Variable**} & **All Patient** & **Non-Cardiomegaly** & **Cardiomegaly** & **\(p\) Value** \\  & **(\(\alpha\) = 129)** & **(\(\alpha\) = 87)** & **(\(\alpha\) = 42)** & **\(p\) Value** \\ \hline \hline \multicolumn{5}{c}{Demographics} \\ Age, years & 61.36 \(\pm\) 11.30 & 60.99 \(\pm\) 11.74 & 62.12 \(\pm\) 10.43 & 0.60 \\ Female sex, \(n\) (\%) & 49 (80.0) & 30 (34.5) & 19 (45.2) & 0.24 \\ Height, cm & 161.38 \(\pm\) 8.30 & 162.15 \(\pm\) 7.91 & 159.41 \(\pm\) 8.83 & 0.07 \\ Weight, kg & 66.49 \(\pm\) 13.41 & 67.38 \(\pm\) 13.53 & 64.65 \(\pm\) 3.133 & 0.28 \\ \hline \multicolumn{5}{c}{Undering disease} \\ Hypertension, \(n\) (\%) & 120 (93.0) & 81 (93.1) & 39 (92.9) & 0.96 \\ Diabetes mellitus, \(n\) (\%) & 81 (62.8) & 54 (62.1) & 27 (64.3) & 0.81 \\ Hypeptidellemia, \(n\) (\%) & 63 (48.8) & 44 (60.6) & 19 (45.2) & 0.57 \\ Gouty arthritis, \(n\) (\%) & 37 (28.7) & 22 (25.3) & 15 (35.7) & 0.22 \\ Coronary arterial disease, \(n\) (\%) & 23 (17.8) & 16 (8.4) & 7 (16.7) & 0.81 \\ Atrial fibrillation, \(n\) (\%) & 10 (7.8) & 4 (4.6) & 6 (14.3) & 0.05 \\ Liver disease, \(n\) (\%) & 44 (34.1) & 29 (33.3) & 15 (35.7) & 0.79 \\ Old stroke, \(n\) (\%) & 12 (9.3) & 6 (6.9) & 6 (14.3) & 0.18 \\ \hline \hline \multicolumn{5}{c}{Laboratory parameters} \\ \hline \hline \multicolumn{5}{c}{BUN, mg/dL} & 68.25 \(\pm\) 17.67 & 68.94 \(\pm\) 18.53 & 66.83 \(\pm\) 15.85 & 0.77 \\ Creatinine, mg/dL & 10.44 \(\pm\) 2.16 & 10.60 \(\pm\) 2.24 & 10.10 \(\pm\) 1.96 & 0.22 \\ BUN/ Cr ratio & 6.69 \(\pm\) 17.4 & 6.63 \(\pm\) 1.66 & 6.82 \(\pm\) 1.90 & 0.66 \\ eCFR, mL/min/173 m\({}^{2}\) & 4.80 \(\pm\) 1.26 & 4.80 \(\pm\) 1.36 & 4.80 \(\pm\) 1.05 & 0.43 \\ Serum osmolality, & 310.35 \(\pm\) 10.36 & 311.56 \(\pm\) 9.72 & 307.83 \(\pm\) 11.28 & 0.05 \\ mOsm/kgH\({}_{2}\)O & 136.33 \(\pm\) 73.49 & 137.77 \(\pm\) 78.24 & 133.33 \(\pm\) 63.28 & 0.85 \\ Sodium, mEg/L & 16.36 \(\pm\) 3.58 & 137.25 \(\pm\) 3.27 & 135.88 \(\pm\) 4.01 & 0.04 \\ Potassium, mEg/L & 4.43 \(\pm\) 0.78 & 4.39 \(\pm\) 0.81 & 4.51 \(\pm\) 0.74 & 0.41 \\ \hline \multicolumn{5}{c}{Cardiothoracic ratio} & 0.48 \(\pm\) 0.06 & 0.45 \(\pm\) 0.03 & 0.55 \(\pm\) 0.04 & \textless{}0.01 \({}^{*}\) \\ \hline \hline \multicolumn{5}{c}{Shirst intensity scale scores} \\ \hline \hline \multicolumn{5}{c}{Thirst scale (VAS)} & 3.26 \(\pm\) 2.44 & 3.29 \(\pm\) 2.35 & 3.19 \(\pm\) 2.65 & 0.70 \\ Thirst scale (CS) & 3.02 \(\pm\) 1.46 & 3.07 \(\pm\) 1.44 & 2.90 \(\pm\) 1.53 & 0.50 \\ \hline \hline \end{tabular} Values are expressed as the mean \(\pm\) standard deviation or number (percentage). Abbreviations: BUN, blood urea nitrogen; BUN/Cr ratio, blood urea nitrogen to creatinine ratio; eGFR, estimated glomerular filtration rate. Note: \({}^{*}p\leq 0.05\).  
\end{table}
Table 1: Baseline characteristics of hemodialysis patients stratified by heart size (\(n\) = 129).  
(\(\beta\) = 0.200 \(\pm\) 0.000, \(p\) = 0.036) and lower salivary conductivity (\(\beta\) = \(-\)0.203 \(\pm\) 0.000, \(p\) = 0.028) were notably associated with a higher CTR (R2 = 0.30, model 1 in Table 2). Previous results have shown the close interaction between salivary conductivity and sodium level [25], and we noticed serum sodium was a significantly negative predictor (\(\beta\) = \(-\)0.178 \(\pm\) 0.001, \(p\) = 0.028) for CTR by removing salivary conductivity from the analysis (R2 = 0.18, model 2 in Table 2).