## 3 Results
In light of the significant results in the univariate Cox regression analysis for CV mortality, the above clinical risk factors of CAD, DM, lower pre-dialytic levels of SPO2, prevalent OSA and albumin concentrations were included in the multivariate Cox regression model. After multivariate adjustment, our data demonstrated that a lower pre-dialytic level of SPO2 was still significantly associated with incremental risks in all-cause mortality (Table 5). Figure 2 illustrated the cumulative event-free survival curves of CV mortality with respect to normal and abnormal groups of pre-dialytic SpO2 divided by 95% after multivariate adjustment in the Cox regression model. The multivariable-adjusted results demonstrated the association between the abnormal pre-dialytic level of SPO2, and CV mortality remained robust (aHR: 0.296 (95% CI: 0.090-0.979); \(p\) values = 0.046). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Variables** & **Non-CV Event Group (\(n\) = 77)** & **CV Event Group (\(n\) = 15)** & \(p\)**Value** \\ \hline Age (years) & 62.8 \(\pm\) 9.9 & 63.2 \(\pm\) 12.1 & 0.893 \\ Male, \(n\) (\%) & 35 (45.5) & 8 (53.3) & 0.581 \\ Diabetes mellitus, \(n\) (\%) & 26 (33.8) & 10 (66.7) & \textless{}0.05 \\ Obstructive sleep apnea, \(n\) (\%) & 5 (6.5) & 5 (33.3) & \textless{}0.05 \\ Hypertension, \(n\) (\%) & 32 (41.6) & 8 (53.3) & 0.406 \\ Prior coronary artery disease, \(n\) (\%) & 25 (32.5) & 11 (73.3) & \textless{}0.05 \\ Pre-dialytic SpO2 (\%) & 95.0 \(\pm\) 2.4 & 92.7 \(\pm\) 5.7 & \textless{}0.05 \\ Body weight (kg) & 61.0 \(\pm\) 9.9 & 60.2 \(\pm\) 9.8 & 0.762 \\ Body mass index (kg/m\({}^{2}\)) & 24.0 \(\pm\) 2.8 & 23.4 \(\pm\) 2.9 & 0.489 \\ Systolic blood pressure (mmHg) & 138 \(\pm\) 25 & 146 \(\pm\) 31 & 0.288 \\ Diastolic blood pressure (mmHg) & 79 \(\pm\) 15 & 83 \(\pm\) 25 & 0.371 \\ Aspartate aminotransferase (IU/L) & 16.6 \(\pm\) 8.2 & 16.9 \(\pm\) 5.7 & 0.903 \\ Albumin (g/dL) & 3.9 \(\pm\) 0.5 & 3.7 \(\pm\) 0.4 & 0.066 \\ Total cholesterol (mg/dL) & 197.4 \(\pm\) 53.9 & 211.5 \(\pm\) 52.5 & 0.356 \\ Triglyceride (mg/dL) & 227.3 \(\pm\) 200.0 & 214.9 \(\pm\) 70.0 & 0.677 \\ Blood urea nitrogen (mg/dL) & 65.6 \(\pm\) 15.4 & 65.1 \(\pm\) 20.6 & 0.918 \\ Creatinine (mg/dL) & 10.2 \(\pm\) 1.7 & 10.7 \(\pm\) 1.4 & 0.264 \\ Uric acid (mg/dL) & 7.5 \(\pm\) 1.3 & 7.9 \(\pm\) 1.7 & 0.395 \\ Potassium (mmol L\({}^{-1}\)) & 4.6 \(\pm\) 0.9 & 4.4 \(\pm\) 0.7 & 0.469 \\ Adjusted calcium (mg/dL) & 9.4 \(\pm\) 0.8 & 9.2 \(\pm\) 0.9 & 0.294 \\ Phosphate (mg/dL) & 4.6 \(\pm\) 1.6 & 4.8 \(\pm\) 1.0 & 0.606 \\ Iron (ug/dL) & 81.1 \(\pm\) 33.7 & 66.0 \(\pm\) 15.6 & 0.093 \\ Ferritin (ng/mL) & 603.5 \(\pm\) 306.7 & 654.2 \(\pm\) 362.5 & 0.573 \\ Hemoglobin (g/dL) & 10.7 \(\pm\) 1.5 & 10.6 \(\pm\) 1.2 & 0.805 \\ Hematocrit (\%) & 32.0 \(\pm\) 4.4 & 32.0. \(\pm\) 3.6 & 0.932 \\ Platelet (k/\(\mu\)L) & 192.6 \(\pm\) 66.9 & 200.0 \(\pm\) 48.2 & 0.683 \\ \hline \hline \end{tabular} Continuous variables were abbreviated as mean \(\pm\) SD. Categorical variables are abbreviated as \(n\) (\%). SpO2 = pulse oximeter saturation.  
\end{table} 
Table 3: The comparison bio-clinical parameters between non-CV event group and CV event group according to CV mortality.