World J Surg DOI 10.1007/s00268-014-2710-0
SCIENTIFIC REVIEW
Mesh Repair Versus Non-Mesh Repair for Strangulated Inguinal Hernia: Systematic Review with Meta-Analysis Hassen Hentati • Wajih Dougaz • Chadli Dziri
Ó Socie´te´ Internationale de Chirurgie 2014
Abstract Background The optimal technique to cure strangulated inguinal hernia remains controversial. The use of mesh in cases of strangulated hernia is still debated due to the potential risk of infection. Objective This systematic review aimed to determine whether or not the mesh repair technique is associated with a higher risk of surgical site infection than non-mesh techniques for strangulated inguinal hernias in adults. Methods An electronic search of the relevant literature was performed on 15 December 2012 using the following databases: MEDLINE, the Cochrane Library, Scopus, Embase, and the Web of Science. Articles reporting a comparison between the mesh repair technique and a non-mesh technique to treat strangulated inguinal hernias in adults, and published in the English or French language in a peer-reviewed journal, were considered for analysis. The quality of randomized controlled trials (RCTs) was assessed using the Jadad scoring system. To assess the quality of nonrandomized trials, we used the Methodological Index for Non-Randomized Studies (MINORS). Results A total of 232 papers was found in the initial search; nine were included in the meta-analysis. The wound infection rate in the mesh repair technique group was lower than in the control group, with a trend towards significance (odds ratio [OR] 0.46, 95 % confidence interval [CI] 0.20–1.07; p = 0.07). The hernia recurrence rate was lower in the mesh repair group (OR 0.2, 95 % CI 0.05–0.78; p = 0.02). Conclusion The mesh repair technique is a good option for the treatment of strangulated inguinal hernias in adults, giving an acceptable wound infection rate and fewer recurrences than non-mesh repair. Our study does not allow us to recommend the use of mesh in cases of bowel resection. We emphasize that, except the two RCTs, the results are predicated on patient selection bias by careful surgeons. Further RCTs are required to obtain more powerful evidence-based data.
Introduction Inguinal hernia repair is the most frequent operation in general surgery [1]. Approximately 10 % of inguinal hernias are diagnosed with incarceration [2, 3]. European
H. Hentati W. Dougaz (&) C. Dziri Department B of General Surgery, Charles Nicolle Hospital, Tunis, Tunisia e-mail:
[email protected]
Hernia Society guidelines state that the mesh repair according to the Lichtenstein technique is the standard treatment of elective inguinal hernia in adults [4]. The optimal technique to cure strangulated inguinal hernia remains controversial. The use of mesh in cases of strangulated hernia is still debated due to the potential risk of infection [3–7]. This systematic review aimed to determine whether or not mesh repair is associated with a higher risk of surgical site infection (SSI) than non-mesh techniques for strangulated inguinal hernias in adults.
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World J Surg Fig. 1 Study flow diagram. RCT randomized clinical trial
An extensive electronic search of the relevant literature was performed on 15 December 2012 using the following databases: MEDLINE, the Cochrane Library, Scopus, Embase, and the Web of Science. Keywords used for the final search in all databases were ‘strangulated hernia,’ ‘incarcerated hernia,’ ‘Lichtenstein,’ ‘mesh,’ and ‘prosthesis’.
strangulated inguinal hernias in adults, and published in English or French in a peer-reviewed journal, were considered for analysis. Studies comparing small bowel resection and no bowel resection in strangulated inguinal hernias treated with mesh repair technique were also considered. Data from editorials, letters to editors, review articles, and case series (fewer than ten cases) were excluded from analysis. Adults (age C18 years) of either sex operated on for strangulated inguinal hernia were included. We excluded patients referred for femoral or ventral hernias.
Inclusion and exclusion criteria
Interventions
All relevant studies reporting a comparison between mesh repair technique and a non-mesh technique to treat
The treatment group comprised patients who underwent inguinal hernia mesh repair according to the Lichtenstein
Methods Search strategy
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World J Surg Table 1 Characteristics of nine studies retained, in alphabetical order Jadad scale
MINORS score
provided that there no signs of generalized peritonitis or contamination of the surgical field.
Author
Type of study
Atila et al., 2010 [7]
Prospective cohort
15/24
Bessa et al., 2007 [17]
Prospective nonrandomized
19/24
Derici et al., 2010 [6] Elsebae et al., 2008 [16]
Retrospective Randomized controlled
9/24
Karatepe et al., 2008 [2]
Randomized controlled
Nieuwenhuizen et al., 2011 [5] Papaziogas et al., 2005 [3]
Retrospective
13/24
Retrospective
14/24
The primary outcome was the occurrence of SSI. SSI was defined as the presence of pus or proven bacterial contamination of the surgical site, whether or not further surgery for treatment was required [12]. This outcome was also evaluated when available in two subgroups: bowel resection and no bowel resection. The secondary outcome was hernia recurrence. Recurrence was defined as a palpable swelling or defect at the previous surgical site in the groin.
Topcu et al., 2013 [15]
Prospective nonrandomized
17/24
Validity assessment
Wysocki et al., 2006 [18]
Retrospective
12/24
The full publications of all possibly relevant abstracts were obtained and formally assessed for inclusion. All studies that met the selection criteria were assessed for methodological quality by two authors (HH, WD). The quality of randomized controlled trials (RCTs) was assessed using the Jadad scoring system [13]. To assess the quality of non-randomized trials, we used the Methodological Index for Non-Randomized Studies (MINORS) index [14]. This index contains 12 items that are scored 0 (not reported), 1 (reported but inadequate), or 2 (reported and adequate). The ideal global score is 24 for comparative studies and 16 for non-comparative studies. Non-randomized studies with a MINORS index higher than 12 for comparative studies and 8 for non-comparative studies were retained for analysis.
Outcome measures
2 3
MINORS Methodological Index for Non-Randomized Studies
technique [8]. Polypropylene mono filament mesh was used in all considered studies. The control group comprised patients treated with any non-mesh repair technique: the Bassini technique [9], the modified Bassini technique [10], and the Shouldice technique [11]. The surgeons chose the type of surgery, and no preference criterion was employed for the repair method to be used for all non-randomized studies. The presence of intestinal ischemia or necrosis was not considered a contraindication for mesh repair in all studies,
Statistical analysis 0
SE(log[OR])
Heterogeneity among studies was assessed by means of the I2 inconsistency test and Cochran’s Q test, a null hypothesis test in which p \ 0.05 is taken to indicate the presence of significant heterogeneity. Selection biases were detected by funnel plots. Overall estimates of treatment effect with their 95 % confidence intervals (CIs) were calculated using the Mantel-Hansel method for fixed models. Results are presented in forest plots. All calculations were carried out using the Review Manager 5.2 software.
0.5 Derici
1
1.5
Results 2 0.01
OR 0.1
1
10
Retrieved reports
100
Fig. 2 Funnel plot of comparison: 1 Mesh repair versus non-mesh repair, outcome: 1.1 wound infection. OR odds ratio, SE standard error
A total of 232 studies were identified from the search (Fig. 1); three were duplicates and were removed. According to the title or abstract, 213 studies were excluded because they did not meet the inclusion criteria: 146
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Lichtenstein
Odds Ratio
Non mesh repair Total Weight
Total
Events
Derici 2010
3
29
6
102
13.6%
1.85 [0.43, 7.89]
Elsebae 2008
1
27
3
27
16.5%
0.31 [0.03, 3.16]
Nieuwenhuizen 2011
1
51
3
25
22.5%
0.15 [0.01, 1.49]
Papaziogas 2005
2
33
4
42
18.9%
0.61 [0.11, 3.57]
Wysocki 2006
0
56
3
21
28.6%
0.05 [0.00, 0.95]
217 100.0%
0.46 [0.20, 1.07]
196
Total (95% CI)
19
7
Total events
Odds Ratio M-H, Fixed, 95% CI
M-H, Fixed, 95% CI
Events
Study or Subgroup
Heterogeneity: Chi² = 6.87, df = 4 (P = 0.14); I² = 42%
0.01
Test for overall effect: Z = 1.80 (P = 0.07)
0.1
Favours [Lichtenstein]
1
10
100
Favours [Non mesh repair]
Fig. 3 Forest plot of comparison: 1 Mesh repair versus non-mesh repair, outcome: 1.1 wound infection. CI confidence interval
0
characteristics of all studies included are listed in Table 1. The study flow diagram is presented in Fig. 1.
SE(log[OR])
Outcomes measures 0.5
Surgical site infection 1
1.5
2 0.01
OR 0.1
1
10
100
Fig. 4 Funnel plot of comparison: 1 Mesh repair versus non-mesh repair, outcome: 1.2 wound infection 2. OR odds ratio, SE standard error
were case reports or small case series, 37 were not related to inguinal hernia, 27 did not report mesh repair according to the Lichtenstein technique, and three were published in languages other than French or English (one in German, one in Italian, and one in Swedish). A total of 16 study reports were considered potentially relevant, and the full text was sought. Seven studies were excluded because they did not report data concerning strangulated inguinal hernias. We retained nine studies for final analysis [2, 3, 5–7, 15–18]: two RCTs, three nonrandomized prospective studies, and four retrospective studies. Except the two RCTs, the results are predicated on patient selection bias by careful surgeons. The
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Five studies comprising 413 patients reported SSI, comparing mesh repair technique with non-mesh techniques (Figs. 2, 3) [3, 5, 6, 16, 18]. A total of 26 wound infections were reported (seven in the mesh repair group and 19 in the control group). The wound infection rate was lower in the mesh repair group than in the control group, but the difference was not statistically significant (odds ratio [OR] 0.46, 95 % CI 0.20–1.07). Heterogeneity was high (I2 = 42 %). Four studies [3, 5, 16, 18] reported ORs (ranging from 0.05 to 0.31) in favor of the mesh repair group; only one [6] showed an OR in favor of the control group, but it was not significant. One study was located on the edge of the funnel plot and was suspected to be a cause of heterogeneity (Fig. 2) [6]. Therefore, after removing this study, we performed a new analysis on the four remaining studies (Figs. 4, 5). Heterogeneity was good (I2 = 0 %). The infection rate in the mesh repair group was statistically lower than in the control group (OR 0.25, 95 % CI 0.08–0.72). Recurrence Three studies [3, 6, 16], with a total of 260 patients (Figs. 6, 7), reported significantly lower recurrence rates in favor of the mesh repair group (OR 0.20, 95 % CI 0.05–0.78). Twenty-seven recurrences were reported (two in the mesh repair group, 25 in the control group). Heterogeneity was low (I2 = 0 %). The three studies [3, 6, 16]
World J Surg
Lichtenstein Non mesh repair
Odds Ratio
Total Weight
M-H, Fixed, 95% CI
Events
Total
Events
Elsebae 2008
1
27
3
27
19.1%
0.31 [0.03, 3.16]
Nieuwenhuizen 2011
1
51
3
25
26.1%
0.15 [0.01, 1.49]
Papaziogas 2005
2
33
4
42
21.8%
0.61 [0.11, 3.57]
Wysocki 2006
0
56
3
21
33.0%
0.05 [0.00, 0.95]
115 100.0%
0.25 [0.08, 0.72]
Study or Subgroup
167
Total (95% CI)
13
4
Total events
Odds Ratio M-H, Fixed, 95% CI
Heterogeneity: Chi² = 2.43, df = 3 (P = 0.49); I² = 0%
0.01 0.1 1 10 100 Favours [Lichtenstein] Favours [Non mesh repair]
Test for overall effect: Z = 2.56 (P = 0.01)
Fig. 5 Forest plot of comparison: 1 mesh repair versus non-mesh repair, outcome: 1.2 wound infection 2. CI confidence interval
0
were in favor of the mesh repair group, with ORs ranging from 0.13 to 0.63 (Fig. 6).
SE(log[OR])
Surgical site infection if bowel resection 0.5
1
1.5
2 0.01
OR 0.1
1
10
Five studies [2, 3, 7, 15, 17], with a total of 221 patients, reported the wound infection rates following mesh repair for strangulated inguinal hernia in two subgroups: bowel resection (experimental group) and no bowel resection (control group). Three studies [2, 15, 17] reported no events and were therefore excluded from the meta-analysis (Figs. 8, 9). Three wound infections occurred (all in the control group). Heterogeneity was low (I2 = 0 %). No statistically significant difference was found between wound infection rates in each group.
100
Discussion Fig. 6 Funnel plot of comparison: 1 Mesh repair versus non-mesh repair, outcome: 1.3 recurrence. OR odds ratio, SE standard error
Lichtenstein
Non mesh repair
Our study showed that the mesh repair technique is a good option for treating strangulated inguinal hernia in adults
Odds Ratio
Events
Total
Events
Derici 2010
1
29
20
102
62.4%
0.15 [0.02, 1.14]
Elsebae 2008
0
27
3
27
25.1%
0.13 [0.01, 2.59]
Papaziogas 2005
1
33
2
42
12.5%
0.63 [0.05, 7.21]
171 100.0%
0.20 [0.05, 0.78]
Study or Subgroup
89
Total (95% CI) Total events
2
M-H, Fixed, 95% CI
Odds Ratio M-H, Fixed, 95% CI
25
Heterogeneity: Chi² = 1.01, df = 2 (P = 0.60); I² = 0% Test for overall effect: Z = 2.32 (P = 0.02)
Total Weight
0.01 0.1 1 10 100 Favours [Lichtenstein] Favours [Non mesh repair]
Fig. 7 Forest plot of comparison: 1 Mesh repair versus non-mesh repair, outcome: 1.3 recurrence. CI confidence interval
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compared with non-mesh techniques, giving better results in terms of SSI and recurrence. Comparing bowel resection and no bowel resection, both mesh repair and non-mesh techniques result in similar SSI rates. Risks of recurrence and complications have to be considered when choosing hernia treatment. It is now established that operation techniques using mesh provide fewer recurrences than non-mesh repairs. The European Hernia Society recommends mesh repair according to the Lichtenstein technique as the ‘best evidence-based option’ for the elective repair of a primary unilateral hernia in adults [4]. However, there has been widespread concern that synthetic materials in emergency interventions for incarcerated and strangulated hernias are too susceptible to
0
SE(log[OR])
0.5
surgical field infection. While there is a common consensus in frankly contaminated fields, such as peritonitis, that prosthetic material should be avoided due to a high risk of infection, mesh repair is still debated in cases of possible infection, such as strangulation, with or without bowel resection. In 2009, a Swedish meta-analysis reported a low risk of wound infection after mesh repair for strangulated inguinal hernia [19]. However, on one hand, the results were not given by means of forest plot, and, on the other hand, the quality assessment and homogeneity of the included studies were not explained. This is the first meta-analysis to compare the mesh repair technique and non-mesh repairs for the treatment of strangulated inguinal hernias in adults. Even though our results seem encouraging in favor of the mesh repair technique, our systematic review is flawed by some problems: the quality of included studies, with only two RCTs; the outcome assessor was not blind in the majority of studies; the data on peri-operative treatment were missing or not comparable, particularly the type and duration of prophylactic antibiotics and the use of suction drainage; and the small number of participants in some studies.
1
Conclusion
1.5
2 0.01
OR 0.1
1
10
100
Fig. 8 Funnel plot of comparison: 2 Mesh repair technique: Bowel resection versus no bowel resection, outcome: 2.1 wound infection. OR odds ratio, SE standard error
Bowel resection
No bowel resection
Total
Events
Atila 2010
0
12
1
72
Bessa 2007
0
4
0
21
Karatepe 2008
0
5
0
16
Papaziogas 2005
0
4
2
29
Topcu 2012
0
8
0
50
Total events
0
Heterogeneity: Chi² = 0.04, df = 1 (P = 0.85); I² = 0% Test for overall effect: Z = 0.35 (P = 0.73)
40.4%
M-H, Fixed, 95% CI
Odds Ratio M-H, Fixed, 95% CI
1.91 [0.07, 49.50] Not estimable Not estimable
59.6%
188 100.0%
33
Total (95% CI)
Odds Ratio
Total Weight
Events
Study or Subgroup
The mesh repair technique is a good option for the treatment of strangulated inguinal hernias in adults, giving an acceptable wound infection rate and fewer recurrences than non-mesh repair. Our study does not allow us to recommend the use of mesh in cases of bowel resection. We emphasize that, except for the two RCTs, the results are predicated on patient selection bias by careful surgeons. Further RCTs are required to obtain more powerful evidence-based data.
1.22 [0.05, 29.86] Not estimable 1.50 [0.15, 14.61]
3 0.01 0.1 1 10 100 Favours [Bowel resection] Favours [No bowel resect]
Fig. 9 Forest plot of comparison: 2 Mesh repair technique: Bowel resection versus no bowel resection, outcome: 2.1 wound infection. CI confidence interval
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Conflict of interest
The authors declared no conflicts of interest.
References 1. Li J, Ji Z, Li Y (2014) Comparison of laparoscopic versus open procedure in the treatment of recurrent inguinal hernia: a metaanalysis of the results. Am J Surg 207(4):602–612 2. Karatepe O, Adas G, Battal M et al (2011) The comparison of preperitoneal and Lichtenstein repair for incarcerated groin hernias: a randomised controlled trial. Int J Surg 6:189–192 3. Papaziogas B, Lazaridis C, Makris J et al (2005) Tension-free repair versus modified Bassini technique (Andrews technique) for strangulated inguinal hernia: a comparative study. Hernia 9:156–159 4. Simons MP, Aufenacker T, Bay-Nilsen M et al (2009) European hernia society guidelines on the treatment of inguinal hernia in adult patients. Hernia 13:343–403 5. Nieuwenhuizen J, Van Ramshorst GH, Ten Brinke JG et al (2011) The use of mesh in acute hernia: frequency and outcome in 99 cases. Hernia 15:297–300 6. Derici H, Unalp H, Nazli O et al (2010) Prosthetic repair of incarcerated inguinal hernias: is it a reliable method? Langenbecks Arch Surg 395:575–579 7. Atila K, Guler S, Inal A (2010) Prosthetic repair of acutely incarcerated groin hernias: a prospective clinical observational cohort study. Langenbecks Arch Surg 395:563–568 8. Amid PK, Shulman AG, Lichtenstein IL (1996) Open ‘‘tension free’’ repair of inguinal hernias: the Lichtenstein technique. Eur J Surg 162(6):447–453 9. Pe´lissier E, Palot JP, Ngo P (2007) Traitement chirurgical des hernies inguinales par voie inguinale. In: Encycl Med Chir.
10.
11. 12. 13.
14.
15.
16.
17.
18.
19.
(Elsevier Masson, Paris), Techniques chirurgicales - Appareil digestif, 40–110, p.16 Beattle AD (1963) Inguinal hernia repair: analysis of personal series of 481 cases carried out by modified Bassini technic. Ann Surg 157:244–253 Glassow F (1996) The Shouldice hospital technique. Int Surg 71:148–153 Taylor SG, O’Dwier PG (1999) Chronic groin sepsis following tension-free inguinal hernioplasty. Br J Surg 86:562–565 Jadad AR, Moore RA, Caroll D et al (1996) Assessing the quality of reports of randomized clinical trials: is blinding necessary? Control Clin Trials 17:1–12 Slim K, Nini E, Forestier D et al (2003) Methodological Index for Non-Randomized Studies (minors): development and validation of new instrument. ANZ J Surg 73:712–716 Topcu O, Kurt A, Soylu S et al (2013) Polypropylene mesh repair of incarcerated and strangulated hernias: a prospective clinical study. Surg Today 43:1140–1144 Elsebae MMA, Nasr M, Said M (2008) Tension-free repair versus Bassini technique for strangulated inguinal hernia: a controlled randomized study. Int J Surg 6:302–305 Bessa SS, Katri KM, Abdel-Salam WN et al (2007) Early results from the use of the Lichtenstein repair in the management of strangulated groin hernia. Hernia 11:239–242 Wysocki A, Kulawik J, Poz´niczek M et al (2006) Is the Lichtenstein operation of strangulated groin hernia a safe procedure? World J Surg 30:2065–2070. doi:10.1007/s00268-005-0416-z Videhult P, Magnusson J, Thorell A (2009) Low wound infection risk when using surgical meshes in incarcerated inguinal hernia. Meta-analysis of seven prospective studies with 311 patients. Lakartidningen 106:2218–2220
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