Study selection and risk of bias assessment
A total of 347 studies were identified from PubMed and 288 studies were searched from Web of Science online database by the previously mentioned electronic search strategy up to October 31, 2019. Upon a manual search and inspection of the reference lists of other systematic reviews and meta-analyses identified 36 additional relevant studies. After exclusion of duplicates, irrelevant studies or unoriginal studies, there were 106 studies remained and assessed for eligibility by screening the full text. Finally, 19 full-text studies reporting comparative clinical outcomes of U-VATS versus M-VATS met the inclusion criteria and were suitable for meta-analysis. The PRISMA flow chart describing the process of study selection is shown in Fig. 1.
The studies selected for this meta-analysis were conducted in 6 countries which were published before 31st October, 2019. Among these 19 studies, four of them were prospective studies; one of them was RCT; and seven of them were PSM studies. This analysis included 3809 patients, of which 1747 patients underwent U-VATS and 2062 patients underweTnt M-VATS. The quality of the included studies was assessed by the NOS scale and scores ranged from 6 to 8. Table 1 summarized basic characteristics and demographics of the included studies.
Operative Outcomes
In this meta-analysis, the comparison of perioperative outcomes between U-VATS and M-VATS was estimated by intraoperative outcomes (operation time, blood loss, number of resected lymph nodes, and conversion rate) and postoperative outcomes (drainage duration, length of postoperative stay, and pain in POD1). Table 2 summarized the overall comparative outcomes of uniportal and multiportal group.
Table 1
Basic characteristics and demographics of the included studies
First Author | Country | Year of Publication | Study year | Retrospective/ Prospective | Study Type | Patients | Lobe | Seg | TNM8th Stage | NOS score |
Bourdages-Pageau[15] | Canada | 2019 | 2014–2017 | Retrospective | PSM | 722 | 247/247 | 0/0 | T1N0M0 | 8 |
Chang [17] | China Taiwan | 2016 | 2012–2014 | Retrospective | No | 121 | 26/55 | 3/2 | T1-2N0M0 | 7 |
Chung [7] | South Korea | 2015 | 2013–2014 | Retrospective | No | 150 | 90/60 | 0/0 | T1-2N0M0 | 7 |
Dai [18] | China | 2016 | 2013–2015 | Retrospective | PSM | 143 | 63/63 | 0/0 | T1-3N2M0 | 7 |
French [19] | Canada | 2016 | 2014–2015 | Retrospective | PSM | 100 | 40/42 | 10/8 | T1N0M0 | 7 |
Han [20] | South Korea | 2016 | 2006–2015 | Retrospective | No | 439 | 167/212 | 0/0/ | Stage I or II | 7 |
Heo [21] | South Korea | 2017 | 2012–2015 | Retrospective | PSM | 104 | 32/32 | 0/0 | T1-2N0-2M0 | 7 |
Hirai [22] | Japan | 2019 | 2012–2019 | Prospective | No | 212 | 142/70 | 0/0 | T1N0M0 | 7 |
Li[23] | China | 2019 | 2015–2017 | Retrospective | PSM | 492 | 215/232 | 31/14 | NG | 8 |
Lin [14] | China | 2016 | 2013–2014 | Retrospective | No | 67 | 21/46 | 0/0 | NG | 7 |
Liu [9] | China Taiwan | 2016 | 2005–2014 | Retrospective | No | 442 | 100/342 | 49/47 | NG | 7 |
Liu [24] | China | 2019 | 2015–2016 | Prospective | No | 328 | 166/162 | 0/0 | T1N0M0 | 8 |
McElnay [8] | UK | 2014 | 2012–2013 | Retrospective | No | 110 | 15/95 | 0/0 | NG | 7 |
Mu [10] | China | 2015 | 2014–2015 | Prospective | PSM | 405 | 28/21 | 8/8 | Stage I-III | 8 |
Perna [25] | Spain | 2016 | 2015–2016 | Prospective | RCT | 131 | 51/55 | 0/0 | T1-2N0M0 | 8 |
Shen [26] | China | 2016 | 2013–2014 | Retrospective | PSM | 396 | 100/100 | 0/0 | T1-3N0M0 | 7 |
Song [27] | South Korea | 2017 | 2011–2016 | Retrospective | PSM | 73 | 26/26 | 0/0 | Stage I-III | 7 |
Zhao [28] | China | 2019 | 2013–2015 | Retrospective | No | 129 | 73/56 | 0/0 | Stage I | 7 |
Zhu [29] | China | 2015 | 2014 Aug-2014 Oct | Retrospective | No | 82 | 33/49 | 0/0 | Stage I or II | 7 |
NOS score = Score of Newcastle Ottawa Scale RCT = randomized controlled trial PSM = propensity matched Lobe = Lobectomy | NG = Not given Seg = Segmentectomy TNM8th = 8th edition of TNM classification of lung cancer | |
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Table 2
Summary of the perioperative outcomes between U-VATS and M-VATS in this meta-analysis
| Comparative outcomes | Number of studies | Study group | SMD/WMD/OR | 95%CI | P value | Heterogeneity (I2,P) | Meta-analysis model | Uniportal | Multiportal |
Intraoperative Outcomes | Operation time | 18 | 1732 | 1967 | -0.04 | -0.33 ~ 0.26 | 0.81 | I2 = 94%, p < 0.01 | Random |
Blood loss | 14 | 1374 | 1590 | -0.14 | -0.35 ~ 0.06 | 0.18 | I2 = 86%, P < 0.01 | Random |
Number of resected lymph nodes | 15 | 1391 | 1618 | 0.03 | -0.08 ~ 0.13 | 0.62 | I2 = 45%, p = 0.03 | Random |
Conversion rate | 13 | 1375 | 1358 | 1.27 | 0.83 ~ 1.94 | 0.14 | I2 = 13%, P = 0.32 | Fixed |
Postoperative Outcomes | Drainage duration | 18 | 1322 | 1411 | -0.13 | -0.27 ~ 0.02 | 0.09 | I2 = 68%, p < 0.01 | Random |
Length of postoperative stay | 10 | 931 | 898 | -0.11 | -0.28 ~ 0.07 | 0.22 | I2 = 64%, p < 0.01 | Random |
Pain in POD1 | 5 | 234 | 313 | -0.78 | -1.61 ~ 0.05 | 0.07 | I2 = 97%, p < 0.01 | Random |
Operation Time
A total of 18 studies including 3699 patients provided comparative data on operative duration. The overall operation time was 146.48 ± 55.07 min and 171.70 ± 79.40 min in U-VATS and M-VATS group, respectively. The present meta-analysis revealed that the overall operation time has no significant difference between U-VATS group and M-VATS group (SMD=-0.04, 95%CI = (-0.33, 0.26), P = 0.81, Fig. 2a). Random-effect model was used due to the high heterogeneity (I2 = 94%, P < 0.01). Subgroup analysis of PSM&RCT studies further confirmed the comparable operation time between two approaches ((SMD = 0, 95%CI = (-0.21, 0.22)) was consistent with the overall value.
Blood Loss
Blood Loss was reported in 14 studies with a combination of 2964 patients. The overall blood loss was 74.49 ± 109.03 mL and 95.48 ± 133.67 mL in U-VATS and M-VATS group, respectively. The present meta-analysis indicated that the overall blood loss has no significant difference between U-VATS group and M-VATS group (SMD=-0.14, 95%CI = (-0.35, 0.06), P = 0.18, Fig. 2b). Random-effect model was used due to the high heterogeneity (I2 = 86%, P < 0.01). According to subgroup analysis, blood loss in PSM&RCT group (SMD=-0.22, 95%CI = (-0.54, 0.10)) has no significant difference with that in non-PSM group.
Number Of Resected Lymph Nodes
Totally, 15 studies including 3009 patients reported the comparative outcomes of number of resected lymph nodes, which were 17.28 ± 9.46 and 18.31 ± 10.17 in U-VATS and M-VATS groups, respectively. The meta-analysis result of number of resected lymph nodes showed that there was no significant difference between U-VATS and M-VATS group (SMD = 0.03,95%CI=(-0.08,0.13), P = 0.62, Fig. 2c). Number of resected lymph nodes in PSM&RCT group (SMD = 0.03, 95%CI = (-0.08, 0.14)) has no significant difference in non-PSM group. Random-effect model was used due to the moderate heterogeneity (I2 = 25%,P = 0.20).
Conversion Rate
In all, there were 13 studies including 2733 patients reporting conversion rate, which was defined as the rate of conversion to thoracotomy or need extra incisions. In U-VATS group, the total conversion rate was 6.18%, while the total value was 4.34% in M-VATS group. The meta-analysis result of conversion rate showed that there was no significant difference between U-VATS and M-VATS group (OR = 1.27, 95%CI= (0.83, 1.94), Fig. 2d). Fixed-effect model was used due to the low heterogeneity (I2 = 13%, P = 0.32).
Drainage Duration
Drainage duration was defined as the period of time from the operation date to the extubation date. A total of 18 studies with a combination of 2743 patients provided comparative data on length of drainage. The overall duration of drainage was 3.90 ± 2.94 days and 4.44 ± 3.12 days in U-VATS and M-VATS group, respectively. The present meta-analysis indicated that the overall operation time has no significant difference between U-VATS group and M-VATS group (SMD=-0.13, 95%CI = (-0.27, 0.02), P = 0.09, Fig. 3a). And the value of drainage duration in PSM&RCT group (SMD=-0.12, 95%CI = (-0.30, 0.07)) showed consistence with the overall value. Random-effect model was used due to the high heterogeneity (I2 = 68%, P < 0.01).
Length Of Postoperative Stay
There were totally 10 studies including 1829 patients reporting length of postoperative stay. The overall postoperative hospital stay was 6.16 ± 4.40 days in U-VATS group and 6.45 ± 4.80 days in M-VATS group. The present meta-analysis indicated that the length of postoperative stay has no significant difference between U-VATS and M-VATS group (SMD=-0.11, 95%CI= (-0.28, 0.07), P = 0.22, Fig. 3b). According to subgroup analysis, length of postoperative stay in PSM&RCT group was (SMD=-0.01, 95%CI = (-0.18, 0.16)). By the virtue of moderate heterogeneity (I2 = 64%, P < 0.01), random-effect model was applied to this analysis.
Pain in POD1
A total of 5 studies including 547 patients provided comparative outcomes on pain scoring in postoperative day 1 (POD1). All these five included studies utilized the visual analogue scale (VAS) to evaluate pain in POD1, and the overall value of VAS was 3.94 ± 1.68 and 3.59 ± 2.76 in U-VATS and M-VATS group, respectively. Since all these studies utilized the same method to assess pain in POD1, the effective valuables of pain in POD 1 were estimated by WMD. The present meta-analysis indicated that the value of pain in POD1 has no significant difference between U-VATS and M-VATS group (WMD=-0.78, 95%CI= (-1.61, 0.05), P = 0.07, Fig. 3c). Random-effect model was applied due to the high heterogeneity (I2 = 97%, p < 0.01).
Publication Bias
Funnel plots were utilized to graphically describe the publication bias of included studies in operation time, blood loss, number of resected lymph nodes, conversion rate, drainage duration, and length of postoperative stay. All funnel plots (See in Supplementary materials) showed a good symmetric distribution. Then Egger’s test and Begg’s test were used to quantize the publication bias, which demonstrated that there was no significant bias in each outcome.