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Contents lists available at ScienceDirect

International Journal of Surgery journal homepage: www.journal-surgery.net

Original research

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A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials

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Hasanin Al Chalabi*, John Larkin, Brian Mehigan, Paul McCormick GEMS Directorate, General & Colorectal Unit, St James Hospital, Dublin 8, Ireland

h i g h l i g h t s  Safe and reliable method of hernia repair.  The hospital stay between the two arms of the study is equal.  The infection rate post operatively is higher in the open hernia repair group.  The operation time is longer in the laparoscopic group but not statistically significant.  The recurrence of hernia is the same between the study cohorts.

a r t i c l e i n f o

a b s t r a c t

Article history: Received 21 December 2014 Received in revised form 19 April 2015 Accepted 31 May 2015 Available online xxx

Introduction: Development of an incisional hernia after abdominal surgery is a common complication following laparotomy. Following recent advancements in laparoscopic and open repair a literature review has demonstrated no difference in the short term outcomes between open and laparoscopic repair, concluding there was no favourable method of repair over the other and that both techniques are appropriate methods of surgical repair. However, long term outcomes in the available literature between these two approaches were not clearly analysed or described. The objective of this study is to assess the effectiveness and safety of laparoscopic versus open abdominal incisional hernia repair, and to evaluate the short and long term outcomes in regards to hernia recurrence using meta-analysis of all randomised controlled trials from 2008 to end of 2013. Study aims and objectives: Population: Patients who developed an abdominal hernia or abdominal incisional hernia following a laparotomy. Intervention: Two methods of surgical repair, laparoscopic and open abdominal wall hernia repair. Comparison: To compare between laparoscopic and open repair in abdominal wall incisional hernia. Outcome: length of hospital stay, operation time, wound infection and hernia recurrence rate. Methods: This study is a systematic review on all randomized controlled trials of laparoscopic versus open abdominal wall and incisional hernia repair. Medline, Pubmed, Cochrane library, Cinahl and Embase were the databases interrogated. Inclusion & exclusion criteria had been defined. The relevant studies identified from January 2008 to December 2013, are included in the analysis. The primary end point can be described as hernia recurrence, and secondary outcomes can be described as length of hospital stay post operatively, operation time and wound infection. Results: Five randomized controlled trials (RCTs) were identified and included in the final analysis with a total number of 611 patients randomized. Three hundreds and six patients were in the laparoscopic group and 305 patients in the open repair group. The range of follow up in the studies was two months to 35 months. The recurrence rate was similar (P ¼ 0.30), wound infection was higher in the open repair group (P < 0.001), length of hospital stay was not statistically different (P ¼ 0.92), and finally the operation time was longer in the laparoscopic group but did not reach statistical significance (P ¼ 0.05)

Keywords: Laparsocopic hernia repair Abdominal incisional hernia Open ventral hernia repair …etc

* Corresponding author. E-mail address: [email protected] (H. Al Chalabi). http://dx.doi.org/10.1016/j.ijsu.2015.05.050 1743-9191/© 2015 IJS Publishing Group Limited. Published by Elsevier Ltd. All rights reserved.

Please cite this article in press as: H. Al Chalabi, et al., A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials, International Journal of Surgery (2015), http://dx.doi.org/10.1016/j.ijsu.2015.05.050

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Conclusion: The short and long-term outcomes of laparoscopic and open abdominal wall hernia repairs are equivalent; both techniques are safe and credible and the outcomes are very comparable. © 2015 IJS Publishing Group Limited. Published by Elsevier Ltd. All rights reserved.

1. Introduction Ventral hernias can be defined as protrusion of a portion of organ or tissue through an abdominal wall defect [1,2]. The incidence of these hernias can be as high as 13% following abdominal wall surgery [3,4]. An incisional hernia is perceived as a morbidity following an abdominal wall operation. Risk factors that increase the chances of developing these hernias are wound infection, male sex, obesity, abdominal distension, underlying disease process and occasionally poor surgical closure [5,6]. Incisional hernia is associated with significant morbidity such as pain, intestinal obstruction, strangulation, and ischemia of the hernia contents. Despite the improvement in the methods of repair, there is still significant morbidity and even mortality associated with repairs [7]. Surgical intervention is the only method of repair [8], with two techniques available: open repair with or without mesh, and laparoscopic mesh repair. It is estimated that over 120,000 laparotomies are carried out in the United Kingdom every year, with more than 7000 incisional hernia repairs subsequently performed. This represents almost 6%, but the actual incidence of incisional hernia development may be higher, as this figure does not take into account patients who opt not to consider or attend for surgery for either personal or medical reasons [9]. Considering this incidence and the morbidity and mortality associated with the condition and the methods of repair [10], it is quite evident that selecting the ideal method of repair is crucial. Some early evidence showed that laparoscopic incisional hernia repair had a number of disadvantages: the longer operating times, the costs involved with equipment provision and the specialised tools and mesh used. However, several studies have demonstrated that in experienced hands laparoscopic repair takes a similar amount of time compared to open repair [11,12]. Cost benefit analysis has also demonstrated that laparoscopic incisional hernia repair is cost comparable to the open incisional hernia repair even without considering patients benefits such as early hospital discharge and early return to work [13]. Laparoscopic incisional hernia repair was first described by Le Blanc and Booth in 1993 [14]. They demonstrated the benefit of laparoscopic repair in hernia surgery, showing better results and lower complication rates compared to the open method [15]. In the current times, only massive tissue defect with complete loss of abdominal muscle structure is considered unsuitable for laparoscopic approach [16]. But despite the improvement in the hernia repair in the last two decades in terms of the overall technique, results in the eyes of many experts are still unsatisfactory. Incisional hernias repaired with primary suturing have a recurrence rate between 12% and 54% [17,18], whereas the mesh repair recurrence rate can be as high as 36% [19,20]. In addition, the introduction of a foreign body such as the Prolene mesh can lead to serious adverse results, such as pain, infection, fistula, bowel injury and bowel adhesions [21]. The newer models of the mesh products have evolved over time, with more attention in the manufacturing features to avoid the above mentioned complications. Laparoscopic repair had then been recognised as a credible alternative to open hernia repair and had been widely practised since.

The laparoscopic approach entails a minimal access technique with a few stab-like incisions for the use of laparoscopic instruments. The technique does not involve repairing the fascial defect; rather the defect is covered using mesh with or without reducing the hernia sac. A careful and meticulous dissection is fundamental to safe surgery with fewer complications like seroma, infection, bleeding and intestinal injury. Some reports suggest improved results with laparoscopic incisional hernia repair, where recurrence rate is very low at 4.3%, and less wound complication compared to the open technique [22,23]. 1.1. Literature review There is a lack of evidence to support one method of repair over the other. The efficiency and efficacy of laparoscopic repair compared to the open technique is lacking. It is still unclear if one method of repair is superior to the other [24], and it is unknown if one repair method is more appropriate to certain types of hernia in comparison to the other. The clinical guidelines of the Society for Surgery of The Alimentary Tract (SSAT 2005) showed that hernia of less than 3 cm can be repaired primarily without the use of the prosthetic mesh, and any hernia where extensive tissues dissection is required such as in component separation technique is then qualified for open repair, yet any other hernia types that do not fall in the above category can be considered where possible for laparoscopic repair [25]. Hence, the success of the repair need to address the guidelines with taking into consideration the individual circumstances of each hernia, and to plan in advance the best method of repair. Additionally, the current evidence available looks at the best method of repair with various outcomes like recurrence rate, the costs involved, post-operative complications and long term results [32e34]. Sajid 2009 had demonstrated that laparoscopic incisional hernia repair is an acceptable method of surgical approach. The recurrence rate was similar to the open technique, but shorter hospital stay and better pain tolerance. Although the short term results were promising for both techniques, the study could not comment on the long term outcomes similar to Cochrane review 2011 results [26]. Forbes 2009 on the other hand demonstrated that laparoscopic incisional hernia repair is not superior to the open technique in terms of hernia recurrence, but this study included patients with primary hernias also. This potentially could bias some of the results as primary ventral hernias are much easier to repair compared to incisional hernias; however results showed less wound infection rate, less haemorrhage and earlier return to work by almost 50%, but the laparoscopic repair carries higher rate of bowel injury with 2.9% compared to only 0.9% in the open group. Therefore, the study concluded laparoscopic repair is still as safe as the open conventional repair and rather open repair has significant advantages of less small bowel injury and seroma formation [27]. Furthermore, recent researchers have shown that laparoscopic incisional hernia repair is far better than open hernia repair in the short term outcomes, like blood loss and hospital stay, with earlier return to work [28,29], however the long term results remain the main challenge to identify in many of randomised controlled

Please cite this article in press as: H. Al Chalabi, et al., A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials, International Journal of Surgery (2015), http://dx.doi.org/10.1016/j.ijsu.2015.05.050

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trials. As no study had looked into longer follow up period post surgery, the follow up period varied between the studies and meta-analyses and mostly cover up to two years after repair [28,29]. Up to now, there is only limited number of studies that specifically addresses the risks and benefits of laparoscopy in incisional hernia repair. The first Cochrane review was published 2011 [24], and this review included 880 patients in the final analysis, with a total number of ten studies involved. The review included studies from 1999 to 2010, and did not conclude that laparoscopy was the preferred method of repair. The review had identified a lot of heterogeneity in the pooled studies, with challenges addressing the missing outcomes due to heterogeneous studies that came from various backgrounds. This aspect has been addressed in our metaanalysis as heterogeneity was minimised using very strict inclusion and exclusion criteria, and also to include randomised controlled studies only within short time period to avoid diversity and to ensure maximum homogeneity. The clinical heterogeneity was one of the identified weak components in the Cochrane review, and the authors had recognised this shortcoming, as the diverse methods of repair can be seen as a significant cofounder in the final analysis, as it is impossible to unify the surgical repair. The methodological heterogeneity was also mentioned due to various concealment and randomisation diversity, while some trials did not mention much about the blinding techniques, others did not reveal their allocations or randomisation tools. The reviewers of the Cochrane study had acknowledged the difficulties in addressing the results due to the significant and obvious studies diversity. That could explain why the summary in the Cochrane review was soft and not very affirmative, It is however fundamental to highlight that the Cochrane review concluded that laparoscopy is a promising approach but with some emphasis on short term outcomes, and not the long term results. In summary, despite the few randomised controlled trials and retrospective studies available, there is an obvious lack of data that supports one method of repair over the other, and also there is unclear data in most of these studies on long term outcomes. Long term outcome was defined by Cochrane review as the outcome measured after 3 years of follow up, but there is no study or trial looks at that time scale. Since the Cochrane review was published in 2011, where it included studies up to 2010, there are only limited number of randomized controlled trials published since. This systematic review, therefore, will be looking at the suitable studies from 2008 to end of 2013. The rationale behind the choice of this time period was to achieve a meta-analysis with maximum homogeneity in the surgical repair as it is within a very close time frame and surgical repair has become more standardised in recent years. As Cochrane review had looked into retrospective and prospective trials, our analysis looks only at randomised controlled studies within the last six years, and that is to narrow down the outcomes in order to find out if there is any new finding to be added to the Cochrane results. 1.2. Study aims and objectives This is a systematic review with meta-analysis of all the randomised controlled trials from January 2008 to the end of December 2013, through applying the PICO structure, the objectives in this study are: - Population: Patients who developed an abdominal hernia or abdominal incisional hernia following abdominal wall incision or laparotomy that required a surgical intervention to correct the abdominal wall defect are included in the systematic review and the meta-analysis.

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- Intervention: This study is looking at two methods of surgical repair, laparoscopic and open abdominal wall hernia repair. Each method of repair has its own technical approach. Although there are occasional minor differences in the way the repairs are performed, they are generally performed in standardised techniques notwithstanding minor deviations between centres. - Comparison: This is to compare and evaluate the two different methods of repair, i.e., the standardized laparoscopic and open abdominal wall incisional hernia repair. - Outcome: This study is identifying the different outcomes between the two arms of intervention, and to evaluate these as primary and secondary outcomes. Primary outcome includes recurrence rate, secondary outcome includes post operative infection rate, length of hospital stay and length of the operative time. 2. Methods 2.1. Data source A systematic review of all the literature that compares laparoscopic incisional abdominal wall hernia to the open repair was conducted. A systematic search of MEDLINE, EMBASE, CINAHL, PUBMED, Cochrane library, all relevant abstracts, meeting letters and electronic databases was carried out. The search was limited to all the randomised controlled trials with no language restriction between January 2008 and December 2013. Medical subject headings (MeSH) using the terms of laparoscopy, open abdominal incisional hernia repair in conjunction with mesh repair was used. The search was also conducted using further and more specific terms like “laparoscopic incisional hernia”, “abdominal wall hernia” or “ventral hernia”, “open abdominal wall hernia” and “open incisional hernia”. The relevant studies were reviewed, analysed and included in final analysis when considered suitable to the metaanalysis. 2.2. inclusion and exclusion criteria Only randomised controlled trials comparing the laparoscopic abdominal wall incisional hernias to the open repair are included in this review. All non randomised trials, retrospective analysis, reports and abstracts are excluded. Studies on primary hernias are excluded too. The studies compared the standard laparoscopic incisional hernia to the open conventional repair, any experimental studies or techniques that are not considered standard will be removed from the analysis. Studies with no explicit comparison between the two surgical techniques are excluded. The relevant studies are considered from January 2008 to end of December 2013. All the data was extracted and checked by the researcher using standardised methods, all the studies were examined and assessed for certain factors, like study quality, randomisation, blinding, robust methodology and outcomes (Table 3). The PRISMA checklist has been identified and incorporated as part of the standardised reporting system in this study, using systematic review with metaanalysis of all the relevant RCTs. 2.3. Data extraction and analysis Literature was searched from January 2008 to December 2013; the selection process has identified the eligible studies. The information sources were researched twice in order to maximise data extraction. Data extraction was performed by the principal researcher, when any further details were required regarding the original studies data, then original investigators and authors

Please cite this article in press as: H. Al Chalabi, et al., A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials, International Journal of Surgery (2015), http://dx.doi.org/10.1016/j.ijsu.2015.05.050

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Table 1 Show the five studies population characteristics. Trial name

Year

Laparoscopic repair

Open repair

Rogmark

2013

64

69

Eker Itani Asencio Pring

2013 2010 2009 2008

94 73 45 30

100 73 39 24

Follow up duration

Outcomes assessed

8 weeks

QoL, Pain score SF-36, recurrence rate, wound infection, operation time, length of hospital stay Blood loss, operation time, length of hospital stay, wound infection, recurrence rate Pain score, operation time, recurrence rate, wound infection, hospital stay Operation time, length of hospital stay, wound infection, recurrence rate, pain score EQ5D Hernia recurrence, analgesia use, wound infection, length of hospital stay, operation time

35 months 24 months 12 months 27.5 months

morbidity recorded in each study varies; some describe bowel injury and bleeding while other studies include seroma formation, chronic pain and quality of life assessment, these parameters were excluded from the final analysis and considered a factor of heterogeneity, since not all studies have included them all, and therefore they were considered invalid and were excluded.

Table 2 Causes of heterogeneity. Causes of heterogeneity Different randomisation techniques Different inclusion & exclusion criteria Sample size Reported outcomes Variable follow up time period Inconsistent results Different hernia sizes Potential use of various surgical repair techniques

2.6. Assessment of bias

were contacted to ensure obtaining the accurate information if needed. The methodological quality assessment was carried out using standardised criteria based on concealment and randomisation technique, like randomisation allocation, description and sample size. Adding to that, the criteria include patients' characteristics, blinding and outcome assessment, and also the achievement of over 80% follow up [30]. Data extracted from the studies included descriptive assessment of both surgical techniques; laparoscopic and open repair, operative time, post operative wound infection rate, length of hospital stay and duration of follow up. 2.4. Participants characteristics The included participants were patients who suffered from abdominal wall incisional hernias. Pooling of the data from across these studies was considered when homogeneity is sufficient. All other hernia types were excluded from the final analysis. 2.5. Primary and secondary outcomes The primary end point is the hernia recurrence rate. The number of hernia recurrence was identified in each study; the diagnosis of recurrence was established by clinical and/or radiological investigations. Due to different lengths of follow ups in the included studies, the recurrence was defined when mentioned in the studies taking into consideration the variability in follow up time periods. Secondary end points included the post operative wound infection rate, operative time, length of hospital stay in days. The

All the included trials were examined for blinding of outcomes, concealment, allocation, randomisation sequence, completeness of outcome assessment and outcome measurement. In addition, trials were assessed in relation to experience in the surgical repair, and studies were evaluated for any expertise bias. Therefore, risk of bias can be identified within the study when certain outcome measures change sharply suggesting variability in the surgeons' learning curve or difference in the experience of surgeon performing the hernia repair. 2.7. Measures of treatment effect Risk ratio was used with 95% confidence interval for binary measures. If the data was presented in the parametric form (i.e., means and standard deviation) they were used directly in the meta-analysis, and posed no problem. Data reported in the nonparametric form (i.e., Median and interquartile range) can not be used for the meta-analysis, therefore for these studies, the mean was assumed to be the same as the median value. A property of the normal distribution of the data from the 25%e75% percentile (i.e., the inter-quartile range) should span 1.35 standard deviations. Thus the width of the inter-quartile range was used to estimate the standard deviation where this was not reported. A further problem for one of the continuous outcomes was when no measure of spread at all was given. In this instance the standard deviation was assumed to be the average value obtained for each of the other studies in the analysis. 2.8. Assessment for heterogeneity and subgroup analysis There were four outcome variables, two of which were

Table 3 Showing the studies quality and the standardisation criteria. Quality variables

Pring 2008

Asencio 2009

Itani 2010

Rogmark 2013

Eker 2013

Inclusion Exclusion Randomisation Sample-size calculation Lost to follow up Allocation concealment

Yes Yes Yes Not stated No Yes

Yes Yes Yes Yes No No

Yes Yes Yes Yes Not stated Yes

Yes Yes Yes Yes No Yes

Yes Yes Yes Not stated Yes Not stated

Please cite this article in press as: H. Al Chalabi, et al., A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials, International Journal of Surgery (2015), http://dx.doi.org/10.1016/j.ijsu.2015.05.050

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continuous measures and two others were binary outcomes. The heterogeneity of the different studies was assessed. Where there was some evidence of heterogeneity (p < 0.1), random effect models were used for the analysis. Fixed effect models were used when no evidence of heterogeneity was demonstrated. Depending on the degree of heterogeneity, subgroup metaanalysis could be performed. However, in this study the variables in the outcomes were all included in the meta-analysis, but where maximum heterogeneity was found in the outcomes, no meta-analysis was performed, i.e. some outcomes were individual results to some studies where no comparison tool can be used as no similar variable to compare to in the other studies. 2.9. Statistical analysis Pooling of data was performed from all the randomised controlled trials included. Data was expressed as a mean and standard deviation for the continuous variables, and as Odds or risk ratio for non-continuous variables. Statistical analysis was carried out using the Stata software (Verison 13, USA). The student's t-test and ManneWhitney U-Test were also used as appropriate; with PValue less than 0.05 was considered statistically significant. 3. Results The search identified 35 potentially eligible studies since January 2008; thirty studies were excluded for reasons related to deviation from the aim of this analysis. Non-randomised controlled trials were excluded; any study that does not compare the two different techniques directly was not included in the analysis. Five randomised controlled trials were found to meet the inclusion criteria and were included in this meta-analysis. The five trials included the analysis of 611 patients. The characteristics of the trials were summarized in Table 1. All the included trials report on patients who had abdominal

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incisional hernias, and were eligible to either laparoscopic or open repair. Any emergency surgery was excluded from these trials, and only elective surgery was included. Flow chart of the researched studies are shown on Fig. 1. Where specified, randomisation methods were reported on all the five trials. Three trials were computer generated allocations, one trial was a sealed envelope and one trial used a random number sequence. Three trials reported on blinding being applied while two did not mention it. The trials ranged in size from 54 to 194 randomised patients and there was no difference in gender allocation across the entire studies population. The duration of follow up ranged from eight weeks up to 35 months. The reported outcomes in the studies varied widely, two studies reported on visual analogue score while one study looked at analgesia requirement post operatively as a measure of pain scale following each method of repair. Several studies reported on quality of life (QoL) and fatigue score and/or return to work as a measure of outcome. Post operative complications were described with a varied prevalence across the studies, however, the five studies shared four similar outcomes namely recurrence rate, length of hospital stay, operation time and wound infection, and theses were analysed and reported in this study. The quality of life (QoL) assessment is a tool that measures the patients feeling of well being using subjective assessment parameters; it purely relies on patient's own expressions using SF-36 form. Visual analogue score (VAS) is another psychometric assessment scale that uses different subjective characteristics that can be measured directly. Validity and reliability of these assessment tools were measured against research standard protocols to ensure accuracy and to minimize bias. 3.1. Heterogeneity There was clearly some heterogeneity among the five studies.

Fig. 1. PRISMA: flow chart for the researched studies Total number of studies identified was 425, but only five studies were included in final analysis where the rest were excluded due to ineligibility, and do not serve the purpose of this research.

Please cite this article in press as: H. Al Chalabi, et al., A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials, International Journal of Surgery (2015), http://dx.doi.org/10.1016/j.ijsu.2015.05.050

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Population size varied largely across the trials. Complications and outcomes also varied. Types of meshes used and surgical technique did vary slightly between the surgical units and was impossible to unify this, therefore bias in the analysis can not be avoided and caution in data interpretation is advisable. Table 2 lists the various causes of heterogeneity. 3.2. Outcomes There were four outcome variables, two of which were continuous measures (length of hospital stay and operation time), and two others were binary outcomes (recurrence and wound infection). For a meta-analysis of continuous outcomes, it is necessary to have data on the mean and standard deviation for the outcome for each study. Some of the five studies presented this information, and thus posed no problems [31,35]. While Asencio (2009) presented mean and confidence interval, so the latter measure can easily be converted to a standard deviation if the number of subjects is known. There were also some problems with the analysis of the out-

comes. For binary outcomes, differences between methods are usually expressed as risk ratios or odds ratios. Neither of these quantities can be calculated for instances when the outcome did not occur for one or both methods. In this data, there were no wound infections in one trial, and no recurrences in another trial. Thus to include these studies in the analysis it was necessary to adjust the data slightly to allow the risk/odds ratios to be calculated. The heterogeneity of results between the different studies was assessed. Where there was some evidence of heterogeneity (p < 0.1), random effect models were used for the analysis, this was evidently expressed in the operation time among the studies, but

when little or no evidence of heterogeneity was found, then fixed effect models were used. 3.2.1. Operation time The first outcome was the duration of surgery. The analysis of results suggested a high degree of heterogeneity between the studies (p < 0.001). Thus a random-effects analysis was performed. This method suggested that the mean difference in time between the methods (calculated as laparoscopy minus open surgery) was 15 min, with a 95% CI of 0e31 min. This result was of borderline statistical significance (p ¼ 0.05). However, three studies appear to demonstrate longer operating time for laparoscopic repair, while Rogmark (2013) found that laparoscopic repair is quicker than the open with median difference of 10 min, while on the other hand, Pring (2008) expressed no difference. So clearly there is a suggestion that laparoscopic approach took longer than open surgery. A Forest plot illustrating the results for this outcome is shown below:

Forest plot showing operation time. 3.2.2. Length of hospital stay The second outcome examined was the patient length of hospital stay. The results of the five different studies were fairly homogenous with little evidence of any heterogeneity (p ¼ 0.99). As a result a fixed effects analysis was performed. There was a mean difference between groups of less than one day (calculated as laparoscopy minus open surgery), with a 95% CI from 0.22e0.24 days. This difference was not statistically significant (p ¼ 0.92). Therefore there was no difference in the length of hospital stay between the two surgical methods.

Please cite this article in press as: H. Al Chalabi, et al., A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials, International Journal of Surgery (2015), http://dx.doi.org/10.1016/j.ijsu.2015.05.050

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A graphical illustration of the results is shown in the next Forest plot.

Forest plot showing length of hospital stay. 3.2.3. Wound infection rate The occurrence of wound infection was then examined. There was some variation in results between studies, but the degree of heterogeneity was not statistically significant (p ¼ 0.12). As a result a fixed-effects meta-analysis was performed. The results suggested

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a highly significant difference in outcome between the two methods (p < 0.001). The risk ratio (calculated as laparoscopy/open

surgery) was 0.22 with a 95% CI from 0.11 to 0.44. This suggests a lower risk of infection for laparoscopy compared to open surgery. The risk of infection was almost five times lower for laparoscopy than for open surgery. It is clearly demonstrated that open incisional hernia repair carries a higher risk in wound infection compared to the laparoscopic technique. A graphical illustration of the results is shown in the next Forest plot.

Please cite this article in press as: H. Al Chalabi, et al., A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials, International Journal of Surgery (2015), http://dx.doi.org/10.1016/j.ijsu.2015.05.050

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Forest plot showing infection rate. 3.2.4. Recurrence rate The final outcome examined was hernia recurrence. Here there was no evidence of any heterogeneity between studies (p ¼ 0.99), and so a fixed effects model was used. The risk ratio (calculated as laparoscopy/open) was found to be 1.29 with a 95% confidence interval from 0.79 to 2.11, and associated p-value of 0.30. It is quite fundamental to highlight that the Eker (2013) study has over 50% weight on this analysis which potentially could impact significantly on the results; however the final analysis suggested no significant difference in recurrence between the two different methods. It is also crucial to point out that the follow up time period is the key to identify recurrence. The duration of follow up varied between the studies as it ranged from two up to 35 months, and this could affect the analysis, as longer follow up could yield further recurrences, therefore cautious interpretation of these findings is important. The results are shown graphically below.

Forest plot showing recurrence rate. 4. Discussion Laparoscopic incisional abdominal wall hernia repair is a relatively new and evolving technique with the potential to replace open repair. The efficacy and safety of the laparoscopic incisional hernia repair is still unclear, as the available evidence comparing the two surgical methods of repair is limited. Despite the Cochrane review (2011) which analysed retrospective and prospective studies, the comparison undertaken here was quite challenging due to different and variable trials included with very heterogeneous backgrounds, meaning that study cohesion and consistency might have been a barrier to the formation of a strong conclusion. However the available data from our meta-analysis suggest that laparoscopic repair is as efficient as open repair if not superior. While this meta-analysis has shown that the recurrence rate

between the two methods of repair is very similar with a P value of 0.30, some other trials have reported lower hernia recurrence with a laparoscopic approach [22,23]. It is not clear yet whether laparoscopic repair can result in less recurrence, as no clear conclusion can be reached because of the limited data available, the fact that studies are relatively of short follow up, and that the published studies are so heterogenous. Nevertheless; with the laparoscopic approach, unlike the open technique it is technically possible to identify all hernia defects, not just the main one. This allows for the use of larger meshes covering all defects including those that are not clinically or radiologically evident likely leading to a reduction in recurrence or indeed new hernia development. It is also crucial to mention that the follow up period in the five randomised controlled trials included varied between two and 35 months, this could to some extent determine the outcome measures, where longer follow up time period could have demonstrated more hernia recurrence. The outcome from this meta-analysis demonstrated a borderline statistical difference in the operating time among the trials,

with the P value is at 0.05. The mean difference in this metaanalysis was 15 min with confidence interval of 0e31 min. This statistical finding is not conclusive and considering the heterogeneity observed, this meta-analysis can not strongly support the idea that laparoscopic repair is necessarily longer than open surgery. Three RCTs [30e32] in this study demonstrated a considerably longer operating time with the laparoscopic approach, while one trial [33] reported a shorter operating time with the laparoscopic repair. On the other hand, Pring 2008 showed no difference in the length of operation in both laparoscopic and open repair [35]. Several other studies have reported no significant difference in operation duration between the two methods of repair, supporting our findings [11,36]. Some of the outcome data from these studies was so heterogeneous so that analysis was not possible as comparison could not be performed in this study. Three trials reported on pain control. While Rogmark (2013) used the visual analogue score, others used

Please cite this article in press as: H. Al Chalabi, et al., A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials, International Journal of Surgery (2015), http://dx.doi.org/10.1016/j.ijsu.2015.05.050

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the QoL assessment with SF-36 as a tool to measure the pain intensity post operatively. Asencio (2009) used a different pain measurement tool to evaluate the pain after surgery, namely EQ5D while not all studies included the pain scale as an outcome. This heterogeneity was perceived as a limiting factor in performing the analysis regarding pain outcomes, and hence it was not included in the final analysis. Similarly only one trial described the amount of blood loss as an outcome measure and so this also excluded [31]. This study examined the length of hospital stay; the outcome in this meta-analysis is quite clear where fairly homogenous studies were compared. There was no difference in the hospital stay between the two methods of repair in all the included RCTs. Several observational studies have compared the length of hospital stay and found that laparoscopic repair had a reduced length of stay compared to open repair [37e39]. One meta-analysis demonstrated a significant reduction in length of hospital stay in the laparoscopic group by two days (open repair 4 days versus laparoscopic repair 2 days), but the authors had highlighted that most of their studies were retrospective and only one randomised controlled trial was included [40]. Finally, this study examined the wound infection rate post operatively; with the findings significantly in favour of laparoscopic repair. The lower risk of wound infection after laparoscopic surgery was demonstrated with a significant statistical outcome (p < 0.001), with RR ¼ 0.11 to 0.44 (95% CI), so five times lower chance of wound infection when laparoscopic option was used instead of open repair. Our finding is very much in line with the findings of other studies, where many authors found fewer complications post laparoscopic repair leading to less infection rate, our results are consistent with these studies [41e43]. It is well understood that open incisional hernia repair requires extensive soft tissue dissection, raising skin flaps and undermining the various abdominal wall layers, this contributes to increased morbidity and local complications post operatively. Some authors have reported on other complications after surgery, such as seroma formation, mesh infection and small bowel injury. The nature of complications differ widely between the two repair techniques: with open surgery it is mainly wound and infection related complications that are generally considered low risk, while complications in laparoscopic repair can be quite serious and life threatening [44,45], including unrecognised small bowel injury. Additionally, studies use several definitions to what constitutes a complication, making the studies' findings very heterogeneous, and rendering comparisons across studies difficult. Reported complications are therefore largely subjective, and objective assessment of complications in future randomised studies should be encouraged. When our results were compared to the Cochrane review findings from 2011, it is clearly the rationale was to achieve more stratified measures to evaluate certain outcomes compared to the Cochrane review, and since Cochrane results were very broad and widely spread across all the spectrum of the studies findings, this would not serve the purpose of this analysis as the comparison in our outcomes was very focused and narrowed to allow identifying specific objectives and then to be able to perform the statistical tests with little heterogeneity. This meta-analysis has several limitations. First, post operative pain, which is considered an important outcome in hernia repair, was not possible to assess and analyse, as discussed above. The included trials in this analysis had under reported pain control post surgery. Pain measurement tool was used in three studies only and were very different, by which direct comparison is not feasible. The clinical observations reported better pain control post operatively in laparoscopic surgery [38], however; rigorous assessment with more dedicated studies are required.

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Second, this meta-analysis did not consider detailed examination of the complications from the two surgical techniques. This study looked only at wound infection rate, however; it was highlighted in the study that other complications can arise like injury to small intestine, mesh infection and Seroma formation. This study had narrowed the outcomes to include the wound factor only to avoid data attrition and hence poor results, and instead to produce more effective and meaningful outcomes. The third limitation was the challenge to obtain homogenous data across the five RCTs, as some of the data used mean and standard deviations; others had used median and interquartile range. Some of these data had to be converted in order to perform the statistical tests. There were also some difficulties with outcome analysis as some outcomes were not assessed in certain trials, e.g. no wound infections in one trial and no recurrence rate in another. Therefore to include these studies in the analysis it was necessary to adjust the data somewhat to allow the risk/odds ratios to be calculated. Fourth, this study acknowledged the duration of follow up in the trials included is in general of relatively short duration excepting one trial of 35 months follow up [31]. Observational studies have found that longer follow up time periods will demonstrate more hernia recurrence, hence while Rogmark 2013 reported on recurrence at only eight weeks post operatively and none were seen, this undoubtedly effects the final outcome in the meta-analysis but does not reflect the actual long term outcome. Given the uncertainty about the long term recurrence in incisional hernia repair and lack of data, it is essential to perform long term follow up studies to compare the durability of laparoscopic incisional hernia repair. And finally, the considerably strict inclusion criteria in this meta-analysis is planned in order to have highly selected studies that can be as comparable as possible, with less bias, less deviation from the aims, and to achieve conclusions that are credible and evidence based as possible. Furthermore, this analysis looked only at studies from 2008 to 2013 inclusive where the surgical techniques are within same time frame, experience had been well established and the surgical approach is well beyond experimental stage. 5. Conclusion There is no conclusive evidence to support one method of repair over the other. Laparoscopic repair has been proven to be as effective and safe as open repair. The findings from the metaanalysis shows no difference in length of hospital stay, no difference in hernia recurrence and no difference in duration of operating time between the two methods of surgical repair. It has however shown that the laparoscopic technique is associated with five times less wound infections than the open repair. The implications from these findings are: 1. Laparoscopic incisional abdominal wall hernia repair can be used when patient deemed to be suitable for it, and when experience with the necessary technical skills is available. 2. Laparoscopic repair appears to have a significantly reduced rate of wound infection. 3. Future studies are required to be well planned in advance with certain outcome measures to be as homogeneous as possible, e.g. pain and complications. 4. Multi-centre randomized controlled trials should be performed to achieve a credible level of evidence to be used in future metaanalyses. 5. Long follow up periods to observe for hernia recurrence are required in future studies.

Please cite this article in press as: H. Al Chalabi, et al., A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials, International Journal of Surgery (2015), http://dx.doi.org/10.1016/j.ijsu.2015.05.050

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Ethical approval N/A. Funding A complete personal work, no financial support. Author contribution Hasan Al Chalabi e idea and structure, statistical analysis and writing. John Larkin e introduction. Brian Mehigan e literature review. Paul McCormick e Supervisor. Conflict of interest No conflicts of interest. Guarantor Hasan Al Chalabi. References [1] C. Fink, P. Baumann, M.N. Wente, P. Knebel, T. Bruckner, A. Ulrich, J. Werner, M.W. Büchler, M.K. Diener, Incisional hernia rate 3 years after midline laparotomy, Br. J. Surg. 101 (2) (2014) 51e54. [2] W.B. Saunders, Dorland's Pocket Medical Dictionary, Pennsylvania, USA, 1995. [3] S. Lomanto, G. Iyer, A. Shabbir, Laparoscopic versus open ventral hernia mesh repair: a prospective study, Surg. Endosc. 20 (2006) 1030e1035. [4] M. Mudge, L.E. Hughes, Incisional hernia: a 10-year prospective study of incidence and attitudes, Br. J. Surg. 72 (1985) 70e71. [5] K.W. Millikan, Incisional hernia repair, Surg. Clin. N. Am. 83 (2003) 1223e1234. [6] R.W. Luijendijk, W.C.J. Hop, P. van den Tol, D.C.D. de Lange, M.M.J. Braaksma, J.N.M. IJzermans, R.U. Boelhouwer, B.C. de Vries, M.K.M. Salu, J.C.J. Wereldsma, C.M.A. Bruijninckx, J. Jeekel, A comparison of suture repair with mesh repair for incisional hernia, N. Engl. J. Med. 343 (2000) 392e398. [7] D. Flum, K. Horvath, T. Koepsell, Have outcomes of incisional hernia repair improved with time? A population-based analysis, Ann. Surg. 237 (1) (2003) 129e135. [8] K. Cassar, A. Munro, Surgical treatment of incisional hernia, Br. J. Surg. 89 (2002) 534e545. [9] National Health Service, NHS, National Statistics of Operations, 2007. Available online at: http://www.hesonline.nhs.uk (accessed 15.02.14.). [10] R.C. Read, G. Yoder, Recent trends in the management of incisional hernia, Arch. Surg. 124 (1989) 326e329. [11] G. Navarra, C. Musolino, M.L. De Marco, M. Bartolotta, A. Barbera, T. Centorrino, Retromuscular sutured incisional hernia repair: a randomized controlled trial to compare open and laparoscopic approach, Surg. Laparosc. Endosc. Percutan. Tech. 17 (2007) 86e90. [12] S. Olmi, A. Scaini, G.C. Cesana, L. Erba, E. Croce, Laparoscopic versus open incisional hernia repair: an open randomized controlled study, Surg. Endosc. 21 (2007) 555e559. [13] D. Earle, N. Seymour, E. Fellinger, A. Perez, Laparoscopic versus open incisional hernia repair: a single-institution analysis of hospital resource utilization for 884 consecutive cases, Surg. Endosc. 20 (2006) 71e75. [14] K.A. LeBlanc, W.V. Booth, Laparoscopic repair of incisional abdominal hernias using expanded polytetrafluoroethylene: preliminary findings, Surg. Laparosc. Endosc. 3 (1993) 39e41. [15] K.A. LeBlanc, W.V. Booth, J.M. Whitaker, Laparoscopic incisional and ventral herniorrhaphy: our initial 100 patients, Am. J. Surg. 180 (2000) 193e197. [16] LeBlanc K, Allain B, History of Laparoscopic Repair of Ventral Wall Abdominal Hernia, Society of Laparoendoscopic Surgeons. Available online: http:// laparoscopy.blogs.com/prevention_management_3/2010/10/laparoscopicrepair-of-ventral-wall-abdominal-hernia.html. (accessed 20.04.14.). [17] T. Anthony, P.C. Bergen, L.T. Kim, Factors affecting recurrence following incisional herniorrhaphy, World J. Surg. 24 (2000) 95e100. [18] R.W. Luijendijk, W.C. Hop, M.P. van den Tol, A comparison of suture repair with mesh repair for incisional hernia, N. Engl. J. Med. 343 (2000) 392e398. [19] T. Liakakos, I. Karanikas, H. Panagiotidis, Use of marlex mesh in the repair of

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A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials.

Development of an incisional hernia after abdominal surgery is a common complication following laparotomy. Following recent advancements in laparoscop...
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