Literature search results
A total of 25 articles [2–26] were retrieved, of which 18 articles [2, 4–8, 10, 12–15, 17–20, 22, 23, 25] were included in the analysis. The flow chart of the literature screening is shown in Fig. 1. There were 11 cohort studies from prospective databases and 7 cohort studies from retrospective databases. A total of 5795 patients were included in the 18 articles, comprising 1420 patients in the RPD group and 4375 cases in the OPD group. Table 3 shows the basic characteristics and quality evaluation of the included documents.
Table 3
Basic characteristics and quality evaluation of the included documents
Study | Country | Organization | Period | Types | Case | Age | | Gender(m/f) | Quali |
Included studies | | | | | RPDvs.OPD | RPD | OPD | RPD | OPD | ty |
Baimas-George 2020 | [2]USA | Department of General Surgery, Carolinas Medical Center | 2008–2019 | PSM(P) | 38 vs. 38 | 66 (38–84) | 68 (42–81) | 16/22 | 16/22 | 8 |
Bao 2014[4] | USA | Stony Brook University Medical Center,NK | 2009–2011 | R | 39 vs. 38 | 68.0 ± 11.2 | 67.7 ± 12.5 | 13/15 | 13/15 | 7 |
Buchs 2011[6] | USA | Division of General, Minimally Invasive and Robotic Surgery Department of Surgery, University of Illinois at Chicago | 2002–2010 | P | 44 vs. 39 | 63 ± 14.5 | 56 ± 15.8 | 22/22 | 14/25 | 8 |
Cai 2019[7] | China | Department of Hepatobiliary and Pancreatic Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou | 2011–2018 | P | 460 vs. 405 | 66.5 ± 11.0 | 67.5 ± 10.7 | 253/207 | 211/194 | 7 |
Chalikonda 2012[8] | USA | Department of general Surgery, Cleveland Clinic Foundation | 2009–2010 | p | 30 vs. 30 | 62 | 61 | 16/14 | 16/14 | 7 |
Gall 2020[10] | UK | HPB Surgical Unit Dept. of Surgery & Cancer Imperial College London Hammersmith Hospital Campus, London | 2017–2019 | P | 25 vs. 37 | 60.93 ± 12.52 | 62.23 ± 10.76 | 16/19 | 21/16 | 8 |
Ielpo 2019[12] | Spain | Sanchinarro University Hospital, San Pablo CEU University of Madrid | 2008–2016 | P | 17 vs. 17 | 66.8 ± 9.5 | 61.4 ± 11.9 | 8/9 | 10/7 | 7 |
Boggi 2016[5] | Italy | Division of General and Transplant Surgery,University of Pisa | 2008–2014 | P | 83 vs. 36 | 58(21–84) | | 77/123 | | 8 |
Kauffmann 2019[14] | Italy | Division of General and Transplant Surgery,University of Pisa | 2014–2017 | PSM(P) | 24 vs. 26 | 65 (58.5–74.75) | 72.5 (59.75–78.75) | 10/10 | 13/11 | 7 |
Kim HS 2018[15] | Korea | Seoul National University College of Medicine, | 2015–2017 | PSM(P) | 51 vs. 186 | 60.7 ± 11.9 | 65.4 ± 10.1 | 24/27 | 108/78 | 8 |
Lai 2012[17] | China | Pamela Youde Nethersole Eastern Hospital, Hong Kong | 2000–2012 | R | 20 vs. 67 | 66.4 ± 11.9 | 62.1 ± 11.2 | 12/8 | 38/29 | 8 |
Marino 2019[18] | Italy | Department of Surgery, Palermo University | 2014–2016 | P | 35 vs. 35 | 60.4 (43–72) | 62.3 (45–73) | 19/16 | 15/20 | 8 |
McMillan 2017[19] | USA | University of Pittsburgh Medical Center | 2003–2015 | PSM(P) | 185 vs. 2661 | 64(56–72) | | 51.5%male | | 8 |
Mejia 2020[20] | USA | Methodist Dallas Medical Center | 2013–2019 | R | 102 vs. 54 | 66 ± 10.6 | 61.7 ± 14.1 | 53/49 | 30/24 | 8 |
Jin J 2019[13] | China | the Pancreatic Disease Center of the Shanghai Ruijin Hospital | 2003–2017 | R | 39 vs. 44 | 29 (21–41) | 30 (25–38) | 3/15 | 1/32 | 7 |
Shi 2020[22] | China | the Pancreatic Disease Center of the Shanghai Ruijin Hospital | 2017–2018 | PSM(R) | 200 vs. 634 | 60.9 ± 11.4 | 60.1 ± 10.8 | 109/78 | 107/80 | 7 |
Tan 2019[23] | Singapore | Yong Loo Lin School of Medicine | 2014–2016 | PSM(R) | 20 vs. 20 | 65 (37–82) | 64 (46–84) | 11/9 | 11/9 | 7 |
Zhou 2011[25] | China | General Hospital of PLA Second Artillery, Beijing | 2009,1-2009,11 | R | 8 vs. 8 | 65(48–75) | 57(47–77) | 5/3 | 4/F | 5 |
Excluded studies | | | | | | | | | | |
Baker 2015[3] | USA | Department of General Surgery, Carolinas Medical Center | 2012–2013 | R | 22 vs. 49 | 63 (38–82) | 63 (26–86) | 31/18 | 13/9 | |
Napoli 2017[21] | Italy | Division of General and Transplant Surgery,University of Pisa | 2007–2014 | P | 82 vs. 227 | 61.6 (51.9–70.7) | 67.4 (59.7–74.8) | 36/46 | 125/102 | |
Kowalsky 2019[16] | USA | University of Pittsburgh School of Medicine | 2014–2015 | P | 159 vs. 95 | 66.8 ± 9.8 | 67.9 ± 10.9 | 87/72 | 47/48 | |
Varley 2018[24] | USA | University of Pittsburgh Medical Center | 2011–2016 | P | 133 vs. 149 | 66.3 ± 10.6 | 66.3 ± 10.6 | 64/69 | 79/70 | |
ZureiKat 2016[26] | USA | multicenter: University of Pittsburgh School of Medicine etc. | 2011–2015 | R | 211 vs. 817 | 67 (15–86) | 65 (15–93) | 425/392 | 117/94 | |
Girgis M 2019[11] | USA | the National Cancer Database (NCDB) from the University of Pittsburgh Medical Center | 2011–2016 | P | 163 vs. 198 | 66.6 ± 10.9 | 67.6 ± 10.3 | 87/76 | 105/93 | |
Chen S 2015[9] | China | Ruijin Hospital Affiliated to Shanghai Jiaotong University School of Medicine | 2010–2013 | P | 60 vs. 120 | 53.6 ± 13.5 | 53.8 ± 14.3 | 34/26 | 65/55 | |
Note: RPD, robot-assisted pancreaticoduodenectomy; OPD, open pancreaticoduodenectomy; P-review of prospectively collected databases; R- review of retrospective databases;PSM- Propensity score matching; No.-number of; NA, data not accessible; vs., versus; Quality- quality assessment; |
PRISMA 2009 Flow Diagram |
Data synthesis and analysis
In this study, 15 postoperative efficacy outcomes of RPD and OPD were analyzed, and sensitivity analysis was performed for each outcome. The outcomes as shown in Table 1. Subgroup analysis was conducted according to whether studies were prospective, retrospective, or propensity score matching (PSM) cohort, as shown in Table 2.
Table 1
Meta-Analysis Results of All Available Studies in Measured Outcomes
Measured Outcomes | No. Studies | No. Patients | Heterogeneity Test | Model | RR /WMD | 95% CI | P |
| | RPD | OPD | I2(%) | P | | | | |
Operative time (min) | 9 | 468 | 598 | 96 | < 0.00001 | Random | 80.85 | 16.09,145.61 | 0.01 |
Estimated blood loss (ml) | 9 | 410 | 599 | 82 | < 0.00001 | Random | -175.65 | -251.85,-99.44 | < 0.00001 |
Hospital day (d) | 10 | 615 | 757 | 87 | < 0.00001 | Random | -2.95 | -5.33,-0.56 | 0.02 |
Lymph node dissection | 6 | 222 | 217 | 72 | 0.003 | Random | 0.48 | -2.05,3.02 | 0.71 |
R0 rate | 13 | 589 | 513 | 1 | 0.44 | Fixed | 1.05 | 1.00,1.11 | 0.05 |
Overall complication | 10 | 409 | 458 | 33 | 0.14 | Random | 0.78 | 0.64,0.95 | 0.01 |
Bile leakage rate | 6 | 317 | 378 | 0 | 0.6 | Fixed | 0.99 | 0.54,1.83 | 0.98 |
POPF | 15 | 1037 | 1006 | 0 | 0.75 | Fixed | 1 | 0.85,1.19 | 0.97 |
Delayed gastric emptying | 11 | 549 | 681 | 0 | 0.46 | fixed | 0.79 | 0.60,1.03 | 0.08 |
Wound infection | 8 | 391 | 433 | 0 | 0.65 | Fixed | 0.6 | 0.44,0.81 | 0.001 |
Mortality | 14 | 1178 | 1218 | 0 | 0.53 | Fixed | 0.82 | 0.62,1.10 | 0.19 |
Reoperation | 9 | 842 | 843 | 0 | 0.69 | Fixed | 0.61 | 0.41,0.91 | 0.02 |
Transfusion | 9 | 817 | 678 | 36 | 0.13 | Random | 0.56 | 0.42,0.76 | 0.0001 |
Clinical PF | 8 | 969 | 1078 | 0 | 0.68 | Fixed | 0.54 | 0.41,0.70 | < 0.0001 |
Severe complications | 6 | 341 | 322 | 0 | 0.89 | Fixed | 0.98 | 0.71,1.36 | 0.91 |
Note: RPD- robot-assisted pancreaticoduodenectomy; OPD-open pancreaticoduodenectomy; POPF- postoperative pancreatic fistula; PF- pancreatic fistula; CI- Confidence Interval; RR/WMD-Relative Risk/ weighted mean difference; No.-number of; Statistical significant results are shown in bold |
Table 2
Meta-Analysis Results of subgroup analysis in Measured Outcomes
Measured Outcomes | Subgroup | No. Studies | No. Patients | Heterogeneity Test | Model | RR /WMD | 95% CI | P |
| analysis | | RPD | OPD | I2(%) | P | | | | |
Operative time (min) | R | 4 | 243 | 290 | 97 | < 0.00001 | Random | 120.4 | -16.02,256.83 | 0.08 |
| P | 5 | 225 | 308 | 96 | < 0.00001 | Random | 57.52 | -30.98,146.02 | 0.2 |
Estimated blood loss (ml) | R | 4 | 243 | 290 | 79 | 0.002 | Random | -136.55 | -230.64,-42,45 | 0.004 |
| P | 5 | 167 | 309 | 84 | < 0.0001 | Random | -222.80 | -361.50,-84.10 | 0.0002 |
Hospital day (d) | R | 4 | 243 | 290 | 84 | 0.0003 | Random | -5.35 | -9.89,-0.81 | 0.02 |
| P | 6 | 372 | 467 | 88 | < 0.00001 | Random | -1.67 | -4.92,1.59 | 0.32 |
| PSM | 3 | 390 | 525 | 54 | 0.11 | Random | -3.04 | -5.28,-0.81 | 0.008 |
Lymph node dissection | R | 2 | 48 | 95 | 71 | 0.06 | Random | 2.22 | -6.63,2.19 | 0.32 |
| P | 4 | 174 | 122 | 58 | 0.07 | Random | 1.84 | -0.75,4.42 | 0.16 |
R0 rate | R | 5 | 327 | 285 | 0 | 0.42 | Fixed | 1.04 | 0.98,1.10 | 0.25 |
| P | 8 | 262 | 228 | 0 | 0.52 | Fixed | 1.08 | 0.98,1.19 | 0.1 |
| PSM | 4 | 265 | 269 | 0 | 0.49 | Fixed | 1.02 | 0.95,1.09 | 0.59 |
Overall complication | R | 3 | 130 | 82 | 73 | 0.02 | Random | 0.6 | 0.23,1.56 | 0.29 |
| P | 8 | 431 | 528 | 20 | 0.27 | Fixed | 0.94 | 0.84,1.06 | 0.31 |
| PSM | 4 | 247 | 384 | 45 | 0.14 | Random | 0.98 | 0.77,1.25 | 0.87 |
POPF | R | 6 | 281 | 343 | 0 | 0.55 | Fixed | 1.1 | 0.84,1.44 | 0.5 |
| P | 9 | 756 | 663 | 0 | 0.74 | Fixed | 0.96 | 0.78,1.18 | 0.7 |
| PSM | 4 | 269 | 271 | 0 | 0.7 | Fixed | 1.08 | 0.75,1.54 | 0.69 |
Delayed gastric emptying | R | 3 | 227 | 274 | 2 | 0.36 | Fixed | 1.07 | 0.49,2.37 | 0.86 |
| P | 8 | 322 | 407 | 10 | 0.35 | Fixed | 0.73 | 0.56,0.97 | 0.03 |
| PSM | 5 | 320 | 457 | 48 | 0.1 | Random | 0.72 | 0.31,1.65 | 0.44 |
Wound infection | R | 3 | 227 | 274 | 0 | 0.48 | Fixed | 0.67 | 0.49,0.92 | 0.01 |
| P | 5 | 164 | 159 | 0 | 0.73 | Fixed | 0.28 | 0.10,0.79 | 0.02 |
| PSM | 3 | 245 | 245 | 0 | 0.46 | Fixed | 0.66 | 0.48,0.90 | 0.009 |
Mortality | R | 4 | 243 | 243 | 0 | 0.73 | Fixed | 0.73 | 0.3,1.77 | 0.48 |
| P | 10 | 935 | 975 | 15 | 0.31 | Fixed | 0.84 | 0.62,1.13 | 0.25 |
| PSM | 5 | 448 | 583 | 0 | 0.5 | Fixed | 1.01 | 0.69,1.47 | 0.97 |
Reoperation | R | 2 | 207 | 254 | 0 | 0.71 | Fixed | 0.58 | 0.25,1.31 | 0.19 |
| P | 7 | 635 | 589 | 0 | 0.49 | Fixed | 0.63 | 0.40,0.98 | 0.04 |
Transfusion | R | 3 | 150 | 102 | 0 | 0.76 | Fixed | 0.69 | 0.48,0.99 | 0.04 |
| P | 6 | 667 | 576 | 43 | 0.12 | Random | 0.48 | 0.31,0.75 | 0.001 |
Clinical PF | R | 2 | 205 | 220 | 30 | 0.23 | Fixed | 0.61 | 0.36,1.03 | 0.06 |
| P | 6 | 764 | 858 | 0 | 0.6 | Fixed | 0.5 | 0.36,0.71 | < 0.0001 |
| PSM | 3 | 389 | 439 | 0 | 0.85 | Fixed | 0.63 | 0.42,0.96 | 0.03 |
Severe complications | R | 3 | 140 | 107 | 0 | 0.78 | Fixed | 0.75 | 0.33,1.71 | 0.5 |
| P | 3 | 210 | 215 | 0 | 0.71 | Fixed | 1.04 | 0.73,1.49 | 0.84 |
| PSM | 3 | 196 | 198 | 0 | 0.64 | Fixed | 1.01 | 0.70,1.46 | 0.96 |
Note: RPD, robot-assisted pancreaticoduodenectomy; OPD, open pancreaticoduodenectomy; P-review of prospectively collected databases; R- review of retrospective databases;PSM- Propensity score matching; No.-number of; POPF- postoperative pancreatic fistula; PF- pancreatic fistula; CI- confidence interval |
1.1 Comparison of operation time
Nine studies [4–6, 8, 12, 15, 17, 22, 25] reported the operation time. There was a high degree of heterogeneity (I2 = 96%, P < 0.00001) among studies. Using a random-effects model, the WMD was 80.85 (95% CI: 16.09 ~ 145.61; P = 0.01). The operation time in the RPD group was significantly longer than that in the OPD group. Subgroup analysis showed that, in the retrospective cohort studies, the operation time of the RPD group was significantly longer than that of the OPD group (WMD = 120.4, 95% CI: -16.02 ~ 256.83, P = 0.08) and the difference was significant. In the prospective cohort study, the operation time in the RPD group was not significantly different from that in the OPD group (WMD = 57.52, 95% CI: -30.98 ~ 146.02, P = 0.2) (Figs. 2A).
1.2 Comparison of estimated blood loss
Nine studies [4, 6, 8, 10, 12, 15, 17, 22, 25] reported estimated blood loss (EBL). There was a high degree of heterogeneity among the studies (I2 = 82%, P < 0.00001). Using the random-effects model, the combined WMD was − 175.65, 95%CI (-251.85, -99.44), P < 0.0001, the EBL in the RPD group was significantly less than that in the OPD group. Using a random-effects model, the combined WMD was − 175.65,95%CI (251.65, -99.44), P < 0.00001. The EBL in the RPD group was still significantly less than that in the OPD group. Subgroup analysis showed that in both retrospective and prospective cohort studies, the EBL in the RPD group was significantly less than that in the OPD group (WMD =-136.55, 95%CI -230.64, -42.45, P = 0.004; and WMD=-222.8, 95%CI(-361.50, -84.10), P = 0.0002, respectively) (Figs. 2B).
1.3 Comparison of intraoperative blood transfusion
Nine studies [3–5, 7, 8, 11, 13–15] reported the rate of transfusion. There was moderate heterogeneity among these studies (I2 = 36%, P = 0.13). Using a random-effects model, the combined RR was 0.56, 95%CI (0.42, 0.76), P = 0.0001, and the rate of transfusion in the RPD group was significantly lower than that in the OPD group. After sensitivity analysis, the meta-results did not show any reversal changes. However, when Cai et al. [14] was eliminated, the heterogeneity was significantly reduced (I2 = 0%, P = 0.43), the fixed-effects model yielded an RR of 0.65, 95%CI (0.50, 0.86), P = 0.002, and the statistically significant difference remained. In both retrospective and prospective cohort studies, there was a statistically significant difference in the number of transfusion between the RPD group and the OPD group (RR = 0.69, 95% CI: 0.48, 0.99, P = 0.04; RR = 0.48, 95% CI: 0.31, 0.75, P = 0.001, respectively) (Figs. 2C).
1.4 Postoperative hospital stay
Ten studies [4–6, 10, 12, 15, 17, 19, 22, 25] reported the postoperative hospital stay. There was a high degree of heterogeneity among the studies (I2 = 87%, P < 0.00001). Using a random-effects model, the combined WMD was − 2.95, 95% CI (-5.33, -0.56), P = 0.02; there was no statistically significant difference between the RPD group and the OPD group. Subgroup analysis showed that in the retrospective or PSM cohort studies, the hospital stay in the RPD group was significantly shorter than that in the OPD group (WMD = -5.35, 95% CI (-9.89, -0.81), P = 0.02; WMD = -3.04, 95%CI (-5.28, -0.81), P = 0.008, respectively). In the prospective cohort studies, there was no significant difference between the RPD and OPD groups. (Figs. 2D)
1.5 Number of lymph node dissection
Six studies [4–6, 8, 12, 17] reported the number of lymph node dissection. There was moderate heterogeneity among the studies (I2 = 72%, P = 0.003). Using the random-effects model, WMD was 0.48, 95%CI ( -2.05, 3.02), P = 0.71), and there was no statistically significant difference between the two operative methods. Subgroup analysis showed that there was no statistically significant difference between the RPD group and OPD group in both retrospective and prospective cohort studies (WMD = 2.22, 95% CI: -6.63, 2.19, P = 0.32; WMD = 1.84, 95% CI: -0.75, 4.42, P = 0.16, respectively). (Figs. 3A)
1.6 R0 rate
Thirteen studies [2, 4–6, 8, 10, 12, 14, 18, 20, 22, 23, 25] reported the R0 rate of the cutting edge. There was a low degree of heterogeneity (I2 = 1%, P = 0.44) among the studies. Using the fixed-effects model, the combined RR was 1.05, 95%CI (1.01, 1.11), P = 0.05. The R0 rate of the RPD group was significantly higher than that of the OPD group. However, subgroup analysis showed that there was no statistically significant difference between the RPD group and the OPD group in the prospective or retrospective cohort studies (RR = 1.04, 95% CI: 0.98, 1.10, P = 0.25; and RR = 1.08, 95% CI: 0.98, 1.19, P = 0.1, respectively) (Fig. 3B).
1.7 Overall complication
Eleven studies [5, 6, 10, 12, 14, 15, 18–20, 23, 25] reported the overall complication. There was moderate heterogeneity (I2 = 55%, P = 0.01) among the studies. Using the random-effects model, the combined RR was 0.83, 95%CI (0.68,1.01), P = 0.27, with no statistically significant difference. After sensitivity analysis, the meta-analysis results show reversal changes. When studies by McMillan et al. [19] was sequentially eliminated, the heterogeneity was significantly reduced (I2 = 33%, P = 0.14). The combined RR of the random effect model was 0.78, 95%CI (0.64,0.95), P = 0.01, and there was statistically significant difference. Subgroup analysis showed that, in the retrospective, prospective and PSM cohort study, there was no statistically significant difference between the RPD group and OPD group (Fig. 3C).
1.8 Bile leakage rate
Six studies [6, 12, 13, 17, 18, 22] reported the bile leakage rate. There was a low degree of heterogeneity (I2 = 0%, P = 0.6) among the studies. Using a fixed-effects model, the combined RR was 0.99, 95%CI (0.54, 1.83), P = 0.98. There was no statistically significant difference between the RPD and OPD groups. Subgroup analysis showed that there was no significant difference in bile leakage rate between the RPD group and OPD group in the prospective and retrospective cohort studies. (Appendix file 4A)
1.9 Incidence of delayed gastric emptying
Nine studies [2, 4–7, 9, 10, 15, 18] reported the incidence of DGE. There was a low degree of heterogeneity (I2 = 0%, P = 0.46) among the studies. Using the fixed-effects model, the combined RR was 0.98, 95% CI: 0.60, 1.03, P = 0.08), and the difference was not statistically significant. Subgroup analysis showed that there was no significant difference in the incidence of DGE between the RPD group and OPD group for prospective or PSM studies (RR = 1.07, 95% CI: 0.49,2.37, P = 0.86; and RR = 0.72, 95% CI: 0.31, 1.65, P = 0.44, respectively). However, DGE in the RPD group was significantly lower than that in the OPD group among the eight prospective cohort studies. (Appendix file 4B)
2.0 Severe complication
Six studies [10, 13, 14, 19, 20, 23] reported the severe complication. There was a low degree of heterogeneity (I2 = 0%, P = 0.89) among the studies. Using the fixed-effects model, the combined RR was 0.98, 95%CI (0.71,1.36), P = 0.91, with no statistically significant difference. After sensitivity analysis, the meta-analysis showed no reversal changes. Subgroup analysis showed that there was no significant difference between the RPD group and OPD group in either prospective, retrospective or PSM cohort studies. (Appendix file 4C)
2.1 Incidence of clinical PF
Eight studies [7, 10, 12–15, 18, 19, 22] reported the incidence of clinical PF. There was moderate heterogeneity (I2 = 58%, P = 0.58) among the studies. Using a fixed-effects model, the combined RR was 0.54, 95%CI (0.41, 0.70), P < 0.0001). Subgroup analysis showed that the incidence of PF in the RPD group was lower than that in the OPD group in prospective, retrospective and PSM cohort studies (RR = 0.61, 95%CI (0.36, 1.03), P = 0.06; RR = 0.61, 95%CI (0.36, 1.03), P = 0.06; and RR = 0.61, 95%CI (0.36, 1.03), P = 0.06; respectively). (Figs. 4A)
2.2 Wound infection rate
Eight studies [2, 6, 8, 12, 17, 18, 22, 23] reported the number of wound infection rate. There was moderate heterogeneity (I2 = 0%, P = 0.65) among the studies. Using the fixed-effect model, the combined RR was 0.6, 95%CI (0.44,0.81), P = 0.001), with statistical significance. Subgroup analysis showed that in the both retrospective and prospective cohort study, the wound infection rate in the RPD group was significantly lower than that in the OPD group (RR = 0.67, 95%CI: 0.49–0.92, P = 0.01, RR = 0.28, 95%CI: 0.10–0.79, P = 0.02, respectively). (Figs. 4B)
2.3 Reoperation rate
Nine studies [6–8, 10, 12, 14, 17, 18, 22] reported the reoperation rate. There was a low degree of heterogeneity (I2 = 0%, P = 0.69) among the studies. Using the fixed-effects model, the combined RR was 0.61, 95% CI (0.41, 0.91), P = 0.02), with statistical significance. Subgroup analysis showed that there was no significant difference in reoperation rate between the RPD group and the OPD group in the retrospective cohort studies (RR = 0.58, 95% CI (0.25, 1.31), P = 0.19. In a prospective cohort study, the rate of reoperations in the RPD group was less than that in the OPD group, and the difference was significant (RR = 0.63, 95% CI (0.40, 0.98), P = 0.04). (Figs. 4C)
2.4 Incidence of POPF
Fifteen studies [2–7, 9–15, 17, 18] reported the incidence of POPF. There was moderate heterogeneity (I2 = 0%, P = 0.75) among the studies. Using the fixed-effect model, the combined RR was 1.00, 95%CI (0.85,1.19), P = 0.97, and there was no statistically significant difference. Subgroup analysis showed that there was no significant difference in POPF between the RPD group and the OPD group in the prospective, retrospective and PSM studies, respectively (Appendix file 5A).
2.5 Postoperative mortality
Fourteen studies [2, 4–8, 10, 12, 15, 18, 19, 22, 23, 25] reported postoperative mortality. There was a low degree of heterogeneity (I2 = 0%, P = 0.53) among the studies. Using the fixed-effects model, the combined RR was 0.82, 95%CI (0.62,1.10), P = 0.19, with no statistically significant difference. Subgroup analysis showed that there was no significant difference in postoperative mortality between the RPD group and OPD group in the prospective, retrospective and PSM cohort studies (RR = 0.73, 95%CI (0.3, 1.77), P = 0.48; RR = 0.84, 95%CI (0.62, 1.13), P = 0.25; RR = 1.01, 95%CI( 0.69,1.47), P = 0.97, respectively) (Appendix file 5B).
2.6 Sensitivity analysis and bias risk assessment
Sensitivity analysis was carried out in each meta-analysis. The heterogeneity of operation time, estimated blood loss, intraoperative blood transfusion, lymph node dissection, and hospital day was large. After the relevant literature was removed, the heterogeneity was significantly reduced, but the results were not reversed. After the relevant literature was removed, the heterogeneity of overall complication is reduced, but the result reversed. The sensitivity analysis showed that other results were not reversed after sequential removal of each study. The funnel plots of the publications were found to be symmetrical, which suggested no publication bias. No publication bias was detected by Begg’s test and Egger’s test, except for the hospital day in the Egger’s test (Appendix file 3).