To explore the learning curve of modified hand-assisted retroperitoneoscopic living donor nephrectomy (HARPLDN).

The clinical data of 81 consecutive donors who underwent modified HARPLDN from May 2015 to February 2021 were retrospectively evaluated. All procedures were performed by an experienced urologist in laparoscopic surgery. Baseline demographic, laboratory, and clinical perioperative data of the donors were collected. Postoperative complications were classified according to the modified Clavien classification system. The trend was analyzed qualitatively in the operation time (OT) varied with the number of cases during the learning process of modified HARPLDN, which is obtained by the moving average method (MAM). Then the learning curve was quantitatively evaluated by the cumulative sum analysis (CUSUM). According to the x-coordinate corresponding to the vertex of the CUSUM curve, 81 donors were divided into two phases, namely the initial learning phase group and the mastery phase group. The Kolmogorov-Smirnov test was used to confirm whether the data were normal distribution. To compare the initial learning phase group and the mastery phase group, the continuous variables were analyzed with an independent samples t-test or Mann-Whitney U test, and the categorical variables were analyzed with chi-square test or Fisher′s exact test. Statistical significance was defined as P value <0.05.

According to the MAM learning curve, the OT decreased as the number of modified HARPLDN cases increased. After about 40 cases, OT was significantly shortened and thereafter fluctuated around 150 min. According to the CUSUM curve, the CUSUM value increased rapidly in the first 40 donors and reached the peak at the 41st case, the first 41 cases were brought into the initial learning phase group (n=41), and then started to decline. The remain cases were brought into the mastery phase group (n=40). The cases of surgeries-CUSUM learning curve in chronological order was comprehensively analyzed, and the following equation was obtained: y=-166.163+ 4.6951×x+ 0.228×x²-0.004×x³; the highest R² value was 0.679, and P<0.001. In the initial learning phase group, the history of abdominal operation, preoperative serum creatinine, OT, warm ischemia time, intraoperative blood loss and length of stay were 3 cases, (72±12) μmol/L, (166±36) min, 120 s (90-300 s), 50 mL(10-300 mL) and (12.7±2.4) d, respectively; While in the mastery phase group were 10 cases, (62±12) μmol/L, (149±33) min, 90 s(60-180 s), 50 mL(20-200 mL) and (12.4±3.5) d. The differences were statistically significant (χ²=4.699, t=3.750, 2.190 and 0.503, Z=-4.276 and -2.569, all P<0.05). There were no significant differences between the two phases in terms of other aspects (all P>0.05).

The modified HARPLDN used in our hospital is a safe and effective method for kidney transplantation. For urologists with rich experience in laparoscopic surgery, 41 cases of the surgery were needed to finish the initial learning phase of the modified HARPLDN.