## 4 Results
### Demographics of the Study Population
The mean ages were 60.09 years and 71.18 years (\(p<0.001\)), and the mean CCI scores were 2.09 \(\pm\) 1.80 points and 3.85 \(\pm\) 2.50 points (\(p<0.001\)), respectively. In the year before PCI, the mean length of ICU stay (0.16 \(\pm\) 1.69 vs. 0.94 \(\pm\) 6.83 days, \(p<0.001\)), blood transfusion (0.12 \(\pm\) 0.85 vs. 0.88 \(\pm\) 3.82, \(p<0.001\)), and days on mechanical ventilation (0.12 \(\pm\) 1.05 vs. 0.87 \(\pm\) 11.25, \(p=0.0244\)) were significantly different for the surviving and death groups. The surgical variables, including average bags of blood transfused (0.17 \(\pm\) 1.55 vs. 3.42 \(\pm\) 5.78, \(p<0.001\)), days on mechanical ventilation (0.13 \(\pm\) 1.23 vs. 3.45 \(\pm\) 24.23, \(p<0.001\)), length of ICU stay (0.23 \(\pm\) 2.07 vs. 0.65 \(\pm\) 4.80, \(p=0.0063\)), and length of hospital stay (4.29 \(\pm\) 4.74 vs. 9.85 \(\pm\) 12.30 days, \(p<0.001\)) were all significantly different. Most underlying diseases were significantly different for the survival and death groups, including hypertension (4.38% vs. 6.35%, \(p=0.0338\)), hyperlipidemia (71.55% vs. 40.91%, \(p<0.001\)), hyperuricemia (4.38% vs. 2.61%, \(p=0.0204\)), diabetes (42% vs. 56.05%, \(p<0.001\)), liver cirrhosis (0.51% vs. 2.35%, \(p<0.001\)), COPD (9.09% vs. 19.84%, \(p<0.001\)), skin and bone diseases (10.77% vs. 13.75%, \(p=0.0282\)), stroke (8.84% vs. 19.84%, \(p<0.001\)), and HBV (3.28% vs. 1.83%, \(p=0.0262\)). The baseline heart-related characteristics were significantly different for the two groups, including AF (2.69% vs. 9.14%, \(p<0.001\)), CHF (14.73% vs. 46.74%, \(p<0.001\)), PVD (4.12% vs. 8.88%, \(p<0.001\)), ACS (40.99% vs. 56.92%, \(p<0.001\)), malignant dysrhythmia (1.77% vs. 6.96%, \(p<0.001\)), and cardiogenic shock (0.93% vs. 7.57%, \(p<0.001\)). The following renal-related characteristics were significantly \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & & \multicolumn{2}{c}{PCI (n = 2337)} & \(p\)-Value \\ \cline{3-5}
**Variables** & \multicolumn{2}{c}{**Survive (n = 1188)**} & \multicolumn{2}{c}{**Death (n = 1149)**} \\ \cline{3-5}  & \multicolumn{2}{c}{**N (\%)**} & \\ \hline \multicolumn{5}{c}{Infection-related characteristics} \\ \hline X33 & Septicemia & 412 (34.68) & 439 (38.21) & 0.0765 \\ X34 & Lower RTI & 77 (6.48) & 260 (22.63) & \(<\)0.001 \\ X35 & GTI & 123 (10.35) & 247 (21.5) & \(<\)0.001 \\ \hline \multicolumn{5}{c}{Bleeding-related characteristics} \\ \hline X36 & Intracranial bleeding & 13 (1.09) & 28 (2.44) & 0.0135 \\ X37 & TIA & 108 (9.09) & 233 (20.28) & \(<\)0.001 \\ X38 & Gastrointestinal bleeding & 62 (5.22) & 133 (11.58) & \(<\)0.001 \\ X39 & Major bleeding & 44 (3.7) & 52 (4.53) & 0.3169 \\ \hline \multicolumn{5}{c}{Hospital variables} \\ \hline X40 & Hospital status & \begin{tabular}{c} Medical \\ center \\ \end{tabular} & 821 (69.11) & 700 (60.92) & \(<\)0.001 \\  & Non-medical \\  & & center & 367 (30.89) & 449 (39.08) & \\ \hline X41 & Hospital ownership & \
\begin{tabular}{c} Public \\ hospital \\ Private \\ hospital \\ \end{tabular} & 361 (30.39) & 332 (28.89) & 0.4297 \\  & & 827 (69.61) & 817 (71.11) & \\ \hline X42 & Hospital area &
\begin{tabular}{c} Central \\ Northern \\ type \\ Eastern \\ \end{tabular} & 197 (16.58) & 234 (20.37) & \\ X43 & Northern & 647 (54.46) & 467 (40.64) & \(<\)0.001 \\  & & 332 (27.95) & 407 (35.42) & \\  & & Eastern & 12 (1.01) & 41 (3.57) & \\ \hline \hline \end{tabular} ACS, acute coronary syndrome; AKF, acute kidney failure; AF, atrial fibrillation; CABG, coronary artery bypass grafting; CAD, coronary artery disease; CCI, Charlson Comorbidity Index; CHF, congestive heart failure; KD, kidney disease; COPD, chronic obstructive pulmonary disease; CRF, chronic renal failure; GTI, gastrointestinal Infection; ICU, intensive care unit; LOS, length of stay; Lower RTI, lower respiratory tract infections; PCI, percutaneous coronary intervention; PVD, peripheral vascular disease; SD, standard deviation; TIA, transient ischemic attack.  
\end{table}