Renal function outcome
The eGFR was significantly reduced in both groups on postoperative day one (13.7 vs. 19.1 ml/min/1.73 m2 for PN and RN, respectively;p <0.001). In the PN group, the eGFR showed a tendency to recover and followed a quadratic pattern during follow-up. The mean eGFR in the PN group reached preoperative levels in the first and third years (95.6±28.8 and 96.9±28.9 ml/min/1.73 m2, respectively), with no significant difference between those values (p =0.710). However, in the RN group, the eGFR did not recover to baseline, and compared to the preoperative levels, the reduction was significant at the end of the third year (p <0.001; see Table 2). RN increased the risk of renal function decline three-fold compared with PN (p <0.05). Additionally, there was a significant difference between repeated measures of eGFR according to operation type (p <0.001; see figure 1).
Assuming an arbitrary cut-off value for the eGFR of 90 ml/min/1.73 m2, among patients with a preoperative GFR>90, the eGFR decreased similarly in the first year in the two groups (15.9 vs. 21.2 ml/min/1.73 m2 for PN and RN, respectively). Statistical analysis showed that the significant decline in the eGFR was parallel in the two groups (p =0.04). Furthermore, in patients with a baseline eGFR<90, renal function was significantly better preserved in the PN cohort, and the difference between the PN and RN groups was more pronounced (p=0.02). The eGFR level recovered almost to the baseline level in the third postoperative year in the PN group (see figure 2 a-b). The proportions of patients in the two groups requiring hemodialysis did not differ (PN=2.8% vs. RN=3.7%; p =0.29).
Logistic regression analysis was performed to identify the significant risk factors for renal function decline, and the results are shown in Table 3. The presence of coronary artery disease, diabetes, and hypertension had no adverse impacts on the changes in the eGFR (p =0.60, p =0.13, and p =0.13, respectively).