Current evidence on powered versus manual circular staplers in ...

Colorectal anastomotic leakage remains one of the most significant complications in colorectal surgery, affecting up to 30% of cases and leading to severe physiological and psychological consequences for patients [1,2,3]. This complication frequently requires additional interventions such as interventional radiology, reoperations, and stoma creation, all of which profoundly impact patient outcomes and increase morbidity. The management of anastomotic dehiscence also places a substantial burden on healthcare systems, leading to an increase in healthcare resource utilization and associated costs [4,5,6,7,8,9,10].

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Anastomotic leakage results from a multifactorial process involving patient-related factors, surgical technique, and postoperative care. Patient comorbidities, such as poor nutritional status, diabetes, and immunosuppression, are often not modifiable [11], yet prehabilitation programs can have an impact on potentially modifiable risk factors. Therefore, current strategies focus on optimizing the patient’s physiological condition before surgery through prehabilitation protocols [12] and enhancing recovery through multimodal rehabilitation programs like ERAS [13]. Despite these advancements, technical factors during surgery still play a critical role in determining anastomotic outcomes.

In recent years, several technological innovations have been introduced to reduce incidence of anastomotic leakage. Among the most notable are the use of indocyanine green fluorescence imaging for real-time assessment of anastomotic vascularization [14], and the development of new circular staplers designed to improve stapling accuracy and potentially reduce the risk of anastomotic complications. The first of these new circular staplers to appear on the market was the Echelon Powered Circular Stapler (EPCS), which in addition to the powered firing process combines two stapling innovations (3D Stapler design and Gripping Surface Technology) created to improve healing conditions along the anastomotic line [15,16,17]. Subsequently, a three-row circular stapler was developed based on three circular rows of conventional B-shaped staples varying in height [18, 19].

More recently, outcomes have been published of a second new powered circular stapling device, the Intocare Powered Circular Stapler (ICS) [20]. However, this powered circular stapler shares only the automated firing mechanism and staple design in common with the first powered circular stapler (EPCS) [21].

Since the publication of first meta-analysis about EPCS [22], five new studies have emerged [20, 23,24,25]. Given the influx of new data, there is a clear need for a more comprehensive and methodologically rigorous meta-analysis to provide a definitive answer regarding the efficacy of powered circular staplers.

Therefore, the objective of this study was to evaluate the outcomes of powered circular staplers (PCS) compared to two-row manual circular staplers (MCS) in colorectal surgery, focusing on their impact on the incidence of anastomotic leaks and postoperative bleeding. By conducting a comprehensive meta-analysis, this study aims to provide a clear and unbiased assessment of the effectiveness of these stapling devices.

This meta-analysis was registered in PROSPERO (CRD). The study was conducted following the updated PRISMA guidelines [26] for systematic reviews and meta-analyses (Supplementary material. PRISMA).

Search strategy

A comprehensive search in the electronic bibliographic databases PubMed, Embase, and SCOPUS was carried out using the following terms to identify articles for meta-analysis: “powered circular stapler,” “circular powered stapler,” “circular” and “powered” and “stapler,” “Echelon” and “circular” and “stapler,” “Echelon” and “powered” and “circular” and “stapler,” “IntoCare OR ICS” and “circular” “stapler.”. No language restrictions or time limits were applied.

Eligibility criteria

The selection criteria included: comparative studies of the outcomes of PCS versus MCS published in any language in indexed journals, conference abstracts published in index-supported journals, and papers that clearly identified and reported the primary outcome of anastomotic leakage and/or the secondary outcome of anastomotic bleeding.

Anastomotic leakage after anterior resection of colorectal cancer (CRC) was defined as communication between intra- and extraluminal compartments due to a defect in bowel wall integrity at colonic/rectal or colonic/anal anastomoses [27].

Anastomotic bleeding was defined as two or more episodes of rectal bleeding with a concomitant decrease in hemoglobin level requiring endoscopic evaluation [28].

Exclusion criteria included studies that did not meet the inclusion criteria, studies in which the actual number of anastomotic leaks was not specified and animal experimental studies.

Selection of studies and data extraction

Two authors (VPM and JMA) independently searched the three bibliographic databases used. Each author then carried out a selection of relevant studies based on the PICO’s eligibility criteria [29]. The study population comprised patients aged > 18 years who underwent circular stapler colorectal anastomosis, the intervention included the use of PCS, a comparison between PCS and MCS was performed, and the main outcome was anastomotic leak while the secondary outcome evaluated was anastomotic bleeding.

Studies meeting the selection criteria were then evaluated via title, abstract, and full-text review. Key details from each study were documented in a custom-designed meta-analysis form using Excel . Variables recorded included: authors, year of publication, number of PCS leaks, number of cases without PCS leaks, total number of PCS cases, number of MCS leaks, number of cases without MCS leaks, total number of MCS cases, and pathologies included in the study (mixed or malignant exclusively).

After the selection of studies, the two authors compared their results for the final selection of publications. In cases of uncertainty or disagreement, a third author (DMV) was consulted to resolve the identified discrepancies.

Risk of bias and quality assessment

All studies were independently evaluated by two authors (JMA and VPM) using the ROBINS I tool [30]. A third author (DMV) confirmed the final determination after discussion.

GRADE methodology was used to assess the overall quality of evidence [31,32,33,34]. GRADE classifies evidence or results into one of four levels: high, moderate, low and very low. Risk of bias, inconsistency, inaccuracy, indirect evidence, or a strong likelihood of publication bias are criteria that can decrease confidence in the results by one or two levels depending on the severity of the issue. We also created a GRADE table to summarize the study.

Assessment of risk of publication bias

In this study, funnel plots were constructed to visualize publication bias, and Egger’s test was employed for further assessment. Additionally, we investigated the potential for p-hacking, which involves the manipulation or selective reporting of data to achieve statistical significance. In the context of meta-analysis, the presence of p-hacking introduces potential bias, compromising the statistical integrity and reliability of the findings. To evaluate the risk of publication bias and p-hacking, we conducted specific analyses, including right-skewness and flatness tests, which allow a rigorous evaluation of potential biases in the reported results.

Statistical analysis

The association between stapler type and the occurrence of anastomotic complications, such as leakage or bleeding, was evaluated by calculating the odds ratio (OR) and its corresponding 95% confidence interval (95% CI). The OR represents the likelihood of an event occurring in the PCS group compared to the MCS group. To further illustrate the differences between these staplers, the risk difference for anastomotic leakage and bleeding was also calculated across the included studies.

Subgroup analyses based on pathology type and year of publication were conducted to determine whether the results were homogeneous across these variables. Additionally, the Mantel–Haenszel method was used to pool the odds ratios (ORs) for the relevant outcomes, employing a random-effects model. Statistical heterogeneity between studies was assessed using the chi-square test, with p-value < 0.1 or I2 > 50% considered indicative of significant heterogeneity. Both Cochrane’s Q test and Higgins’ I2 statistic were utilized to evaluate inter-study heterogeneity. The choice between the random-effects and common-effects models was based on the level of heterogeneity observed in the included studies.

The patient populations exhibited variability in surgical techniques, demographic characteristics, and clinical conditions, reflecting a diverse, global representation. The random-effects model was selected to account for both within-study and between-study variability, providing a more conservative and generalizable estimation of the overall treatment effect. This approach acknowledges the inherent heterogeneity due to differences in surgeon expertise, geographic locations, and patient characteristics, thereby offering a more robust synthesis of evidence.

To explore potential sources of heterogeneity, subgroup analyses and sensitivity analyses were performed. Additionally, outlier detection tests were used to identify studies with extreme results, and influence analyses were conducted to assess the impact of individual studies on the overall meta-analysis.

Statistical analyses were performed using RStudio statistical software with R (version 4.3.0) with dmetar, meta, and metafor libraries. The significance level was set at p ≤ 0.05, and all p-values were two-tailed.

Study selection and description

The search in the electronic bibliographic databases yielded studies that met the research criteria (Fig. 1). Finally, 12 articles were selected for meta-analysis. One abstract publication was excluded due to duplicity as the study has been subsequently published [6, 35].

The inclusion of the two studies by Pla V et al. [6, 36] was critically evaluated by the two primary investigators. This assessment was further validated by an independent third reviewer, confirming the appropriateness of including both studies in the meta-analysis.

The characteristics of the studies included in the meta-analysis (Table 1) revealed that most were retrospective observational studies, utilizing propensity score matching for case selection in both the PCS and MCS groups (6,23,25,36–41). Six studies encompassed both benign and malignant pathologies [6, 24, 36,37,38], while five focused exclusively on colorectal cancer [20, 23, 25, 39, 40]. The surgical approaches varied between laparoscopic, open, and robotic techniques.

The risk of bias was high in two studies (Fig. 2). In the remaining six studies, the risk of bias was moderate, primarily due to potential confounding factors. All other assessed domains showed a low likelihood of bias.

Risk estimation of anastomotic leakage

All included studies

A total of patients were included in the meta-analysis, with MCS being the most frequently used device (MCS: cases vs. PCS: cases). Among all studies, 251 cases of anastomotic leakage were reported (3.84%), affecting 56 patients in the PCS group (3.51%) and 195 patients in the MCS group (6.92%). Due to moderate heterogeneity (I2 52.5%, 95% CI 5.7–76%; Q 21.04, p = 0.021), the random-effects model was applied. The pooled odds ratio (OR) was 0.523 (95% CI 0.306–0.898, p = 0.019), indicating a protective effect of PCS in reducing anastomotic leakage (Fig. 3). The risk difference (RD) between PCS and MCS was − 0.033 (95% CI − 0.06 to − 0.006), suggesting that 31 patients would need to be treated with PCS to prevent one case of leakage.

Subgroup analysis revealed substantial heterogeneity in studies involving mixed pathologies (I2 76%, τ2 0.952, p < 0.01), with an OR of 0.56 (95% CI 0.23–1.35) (Fig. 4). In contrast, studies focusing exclusively on neoplasms demonstrated no heterogeneity (I2 0%, τ2 0, p = 0.88).

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An analysis by year of publication indicated a worsening of clinical outcomes and increased heterogeneity, particularly in studies from (Fig. 5). Regarding the type of stapler, the EPCS group demonstrated an OR of 0.52 (95% CI 0.32–0.97), while the combined EPCS + ICS group and ICS group showed higher heterogeneity and less robust results (I2 63%, p < 0.01) (Fig. 6).

The Labbe plot suggested moderate heterogeneity, with the findings of Lie JJ et al. being identified as an outlier (Fig. 7). Sensitivity analysis confirmed that this study contributed significantly to the observed heterogeneity (Fig. 8). Excluding Lie JJ et al. resulted in a marked reduction in heterogeneity (I2 0%, τ2 0%, Q 6.98, p = 0.64), allowing for the use of a common-effects model. After exclusion, the OR for leakage risk with PCS was 0.41 (95% CI 0.29–0.58), with a relative risk reduction (RR) of − 0.04 (95% CI − 0.06 to − 0.03). Twenty-five patients would need to be treated with PCS to prevent one leakage event (Supplementary Material 1, Figs. 1-2).

Outlier and new powered circular stapler excluded

When both Lie JJ et al. and studies involving ICS devices were excluded, heterogeneity remained low (I2 0%, Q 5.48, p = 0.601). The common-effects model yielded an OR of 0.38 (95% CI 0.26 − 0.55), with a relative risk of −0.05 (95% CI − 0.07 to − 0.03). The number needed to treat (NNT) to prevent one leakage event was 20 (Supplementary Material 2, Figs. 1–2). Subgroup analyses by pathology type and year of publication demonstrated low heterogeneity, and no outliers were identified in the Labbe plot or influence analysis (Supplementary Material 2, Figs. 3–5).

Estimation of the risk of anastomotic bleeding

All included studies

Five studies reported on anastomotic bleeding, with one study reporting no cases. Among the patients included, 143 (4.99%) cases of postoperative anastomotic bleeding were observed, with 8 cases (0.923%) in the PCS group and 135 cases (6.293%) in the MCS group. The common-effects model was used due to low heterogeneity (I2 20.8%, 95% CI 0–66.4%; τ2 0., Q 5.05, p = 0.282) (Fig. 9).

The pooled risk difference for bleeding was − 0.02 (95% CI − 0.04 to 0.01), indicating that 50 patients needed to be treated with PCS to prevent one case of bleeding.

Subgroup analysis by diagnostic category (mixed vs. CRC) showed no significant differences between groups (Q 2.56, p = 0.11; I2 0%) (Fig. 10). The OR was 0.35 (95% CI 0.20–0.59) in the mixed pathology subgroup and 1.25 (95% CI 0.28–5.55) in the CRC subgroup.

When stratified by year, outcomes for were worse than in previous years (Fig. 11). Subgroup analysis by type of stapler showed poorer outcomes in ICS and EPCS + ICS groups (Fig. 12).

Sensitivity analysis showed minimal variation when individual studies were excluded, with two studies (Sylla P et al. and Vignaly A et al.) contributing significantly to model stability. Exclusion of these studies increased heterogeneity to 31–33% and widened confidence intervals. Conversely, exclusion of Lee H et al. had minimal impact, reducing heterogeneity to 12% (Fig. 13). Influence analysis revealed moderate variability in study contributions, with no single study entirely eliminating heterogeneity.

New powered circular stapler excluded

Exclusion of studies involving ICS devices (Chen Y et al. and Lee H et al.) resulted in four studies with low heterogeneity (I2 0%, Q 1.29, p = 0.526). The OR for anastomotic bleeding was 0.20 (95% CI 0.08–0.52), and the relative risk was − 0.03 (95% CI − 0.07 to − 0.01). The NNT to prevent one bleeding event was 34 (Supplementary Material 3, Figs. 1–2).

Subgroup analysis by pathology revealed an OR of 0.35 (95% CI 0.20–0.59) for the mixed pathology group and 0.36 (95% CI 0.21–0.60) for the CRC group, with no outliers observed in Labbe plots or sensitivity analyses. Influence analysis confirmed minimal heterogeneity and consistency across studies.

Assessment of publication bias

Anastomotic leakage

With all studies included in the meta-analysis, the funnel plot for the random-effects model demonstrated a symmetrical distribution of studies. Egger’s test confirmed the absence of significant asymmetry in this plot (intercept: − 7.737, 95% CI − 4.27 to 2.79, p = 0.692) (Fig. 14).

The results of the right-skewness test (p = 0.666) and flatness test (p = 0.049) provide no evidence of significant skewness or flatness in the p-values of the included studies. These findings indicate a low likelihood of p-hacking practices, supporting the overall validity of the meta-analysis.

When the study by Lie JJ et al. was excluded, the funnel plot maintained symmetrical distribution of the remaining studies (Egger’s test: intercept: − 1.49, 95% CI − 3.51 to 0.33, t = 1.623, p = 0.143), and no evidence of p-hacking was observed (Right-skewness test: p = 0.634; flatness test: p = 0.833).

Anastomotic bleeding

For anastomotic bleeding, the funnel plot for the random-effects model and Egger’s test showed no evidence of significant asymmetry in distribution (intercept: 0.988, 95% CI − 2.06 to 2.04, p = 0.640) (Fig. 15). Due to the limited number of cases, however, the right-skewness and flatness tests could not be performed in the anastomotic bleeding analysis. Considering only studies with EPCS, no evidence of significant asymmetry was found (intercept: 0.988, 95% CI − 2.06 to 4.04), p-value: 0.64).

The growing interest in powered circular staplers is evident from the publication timeline of studies included in this meta-analysis, with almost half (45.45%) published in the first three quarters of .

Conducting this meta-analysis presented several challenges, particularly due to the presence of an outlier study [24] and the introduction of a new powered stapling device [20]. The two powered circular staplers have significant differences in their design and operation.

The initial meta-analysis, which included all published studies to date, revealed significant heterogeneity (I2 = 52%), driven primarily by the Lie JJ et al. study [24] which was identified as an outlier. Excluding this study made the overall results more consistent with prior literature, and heterogeneity was significantly reduced (I2 = 0%). The outlying behaviour observed in this study may stem from methodological differences in case selection or unreported confounders.

The initial hypothesis that the results might differ between powered circular staplers was confirmed by subgroup analysis according to the type of stapler used. These differences were evident when all available studies were included, and remained with outlier study exclusion. A protective effect of EPCS against the occurrence of postoperative anastomotic leaks was observed in both cases. Due to the small number of trials using ICS, these results should be treated with caution.

A critical issue identified in the Lie JJ et al. study [24] was the significant selection bias in patient assignment to the experimental and control groups, the former consisting of patients operated on in , while the latter was composed of patients from . Concerns about the validity of this comparison stem from the notably worse outcomes reported for than the control group, which exhibited unexpectedly positive outcomes. Moreover, the decision to use patients from for the control group is puzzling, as more recent data (from – to –) were available and would have provided a more appropriate and contemporaneous comparison. In addition, the surgical techniques used in this study, such as transanal excision of the mesorectum and total proctocolectomies with an ileoanal pouch, were different from those used in previous studies. This raises the question of whether the results of this study are truly comparable to those of previously published studies. Notably, propensity score matching to ensure comparable groups was not performed, further exacerbating the potential for bias.

The use of powered circular staplers may not be justified in experienced hands, according to Lie JJ et al. [24]. The results of this study, expected to be similar to those obtained with conventional devices rather than significantly worse, were obviously surprising [6, 15, 17, 25, 36, 37, 41,42,43,44,45]. The two hypotheses proposed in this study to explain these results should, however, be viewed with caution in the absence of objective evidence.

In the case of anastomotic bleeding, outcomes were superimposable to those reported in previously conducted meta-analyses [22, 46].

The variability in methodological rigor among the included studies is evident in the overall assessment of quality of evidence. While the initial analysis including all trials showed low quality evidence for both anastomotic leakage and bleeding, the level was significantly increased to moderate when excluding outliers and trials using mixed staplers or ICS. This suggests that when only the most methodologically sound studies are considered, there is moderate confidence that EPCS will result in a significant reduction in both anastomotic leakage and bleeding.

Given the potential cost differences between stapling devices, these findings may also have economic implications [6, 7], particularly in institutions where resource allocation is critical. Further cost-effectiveness analyses could help determine whether the benefits of powered staplers justify the higher costs compared to manual devices. Economic studies previously conducted on the PCS device [6, 7], in particular a cost-effectiveness study that was conducted using real-world costs [6], seem to indicate the opposite. These cost-savings are primarily due to the reduction in anastomotic leaks and associated postoperative complications, which typically increase length of hospital stay and healthcare resource utilization. Therefore, adopting advanced stapling technologies offers not only potential clinical benefits but also a clear economic advantage in high-volume centers.

The introduction of a new powered stapling device with a different design in recent studies may have influenced outcomes. Although the powered firing mechanism is popularly believed to be the primary advantage of powered stapling devices, the 3D staple design and gripping surface technology included in EPCS may play a more important role in reducing anastomotic complications. Results from studies using the newer stapler (20,23), which lacks these key features, could support this hypothesis. Despite having a similar staple design and powered firing mechanism, these studies have reported inferior outcomes, particularly in terms of anastomotic leakage. This suggests that while powered firing may contribute to the stability of the anastomotic line during the firing process, thereby decreasing the risk of small tears, the optimal tissue compression and distribution in the anastomosis achieved by 3D stapling formation and gripping surface technology could help improve perfusion and anastomotic healing conditions. These findings are consistent with our group’s hypothesis that the combination of 3D stapling and gripping surface technology are critical factors in improved anastomotic integrity [6, 22].

In this regard, future research should focus on direct comparisons between the different types of powered staplers, paying particular attention to the impact of specific design features (such as staple formation and gripping mechanisms) on anastomotic integrity and complication rates. Prospective randomized trials may help clarify these differences and guide surgeons in making evidence-based decisions in the operating room.

This study integrates all published data comparing powered circular stapling devices with manual staplers in colorectal surgery. The rigorous methodology applied highlighted qualitative differences across studies based on publication date, and the presence of studies with extreme values suggests potential performance differences between the two available powered stapling devices. By excluding studies with probable biases, this analysis provides a clearer, more accurate view of the true outcomes associated with powered circular staplers.

Due to the retrospective nature of the included studies, which may contain biases not accounted for in the analyses, the results of this study should be viewed with caution. The primary limitation of this study is the reliance mainly on retrospective studies, and that only one randomized trial was available, which may reduce the strength of the conclusions. Additionally, two studies included a newer powered stapler that differs in design from the EPCS devices, potentially introducing selection bias and affecting the comparability of outcomes within the powered stapler group.

The group is currently in the recruitment phase of an international, multicenter, randomized clinical trial with eight participating European centres (reference NCT), aimed at rigorous evaluation of EPCS efficacy in reducing the incidence of anastomotic leakage and postoperative bleeding in colorectal surgery. Secondary endpoints include the impact of the device on overall complication rates, surgical efficiency and postoperative recovery time.

In conclusion, this meta-analysis demonstrates that powered circular staplers (PCS), in particular the EPCS, significantly reduce the risk of anastomotic leakage and postoperative bleeding compared with manual circular staplers (MCS). Sensitivity analyses confirmed the robustness of these findings and underscored the importance of careful study selection and standardization to minimize heterogeneity and improve reliability. These results support the use of PCS, in particular EPCS, as the preferred method in colorectal surgery. To validate these findings and address remaining uncertainties, further standardized trials are warranted.

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