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Page 4 of 11 Sawada et al. Mini-invasive Surg 2021;5:6 I http://dx.doi.org/10.20517/2574-1225.2020.100

All statistical tests were performed using JMP Pro 15.1.0. For all statistical analyses, P < 0.05 was considered
statistically significant.

RESULTS
Patient characteristics
As shown in Table 1, a total of 202 patients (131 RAPN and 71 OPN) were included in this study. Prior
to PSM, the patients in the cohort who underwent RAPN had a significantly higher BMI (P = 0.006) than
those who underwent OPN. Furthermore, they had significantly lower RENAL nephrometry scores than
those who underwent OPN (6.8 ± 1.61 vs. 7.5 ± 1.56, respectively; P = 0.003). A total of 116 cases were
compared, comprising 58 RAPN cases and 58 OPN cases that were matched by PSM. In the post-PSM
cohort, there were no differences between the RAPN and OPN groups for any of the covariates assessed (all
P > 0.05) [Figure 1].

Perioperative outcomes and complications
EBL was significantly higher and hospital stay longer in the OPN group than in the RAPN group [Table 2].
Ischemia time was significantly longer in the OPN group than in the RAPN group; however, cold ischemia
time accounted for the majority of the ischemia time in the OPN group.

There were no intraoperative complications in any of the 116 cases selected by PSM. However,
postoperative complications occurred in 11 patients who underwent OPN and 8 patients who underwent
RAPN.

In both patients who underwent RAPN and OPN, postoperative complications of CD grade 3 or higher
included urinomas requiring ureteral stenting and pseudoaneurysms requiring embolization. There was no
significant difference in the incidence of postoperative complications between OPN and RAPN [Table 2].

Pathological outcomes
After PSM, one case of pT2a and one case of pT3a were observed in patients who underwent OPN. There
was no difference between the OPN and RAPN groups in terms of positive surgical margins [Table 3].

Functional outcomes
In the post-PSM cohort, the % preservation of eGFR at both 1 day and 3 months postoperatively was
significantly better in the RAPN group than in the OPN group, although the eGFR at 3 months was not
significantly different between the two groups. There were fewer cases with upstaged CKD grades in the
RAPN group than in the OPN group (30 cases with OPN vs. 17 cases with RAPN; P = 0.014) [Table 3]. The
changes in eGFR for all cases, imperative cases, and elective cases are shown in Figure 2.

Multivariate analysis
In the pre-PSM cohort, RAPN was found to be a good predictor of EBL (P < 0.0001), ischemia time (P <
0.0001), transfusion rate (P = 0.019), hospital stay (P < 0.0001), eGFR (P < 0.0001) and % preservation of
rd
eGFR (P < 0.0001) at the 3 postoperative month (POM), and CKD upstaging (P = 0.001) via multivariate
analysis [Figure 3].

DISCUSSION
Previous studies have shown mixed results when comparing the outcomes of RAPN and OPN. Simhan et al. [11]
compared perioperative outcomes of 281 patients with moderately and highly complex renal lesions.
The results showed that RAPN yielded perioperative and functional outcomes similar to OPN, with
[6]
the additional benefit of shorter hospital stays. Garisto et al. compared perioperative, functional, and