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Figure 1.
Systematic Literature Search Flowchart
Systematic Literature Search Flowchart

MeSH indicates medical subject heading.

Figure 2.
Associations Between Outcome and Repair Type
Associations Between Outcome and Repair Type

A, Hernia recurrence; B, seroma; C, surgical site infection. OR indicates odds ratio.

Table 1.  
Characteristics of the Studies Included in the Meta-analyses
Characteristics of the Studies Included in the Meta-analyses
Table 2.  
Characteristics of Suture and Mesh Use
Characteristics of Suture and Mesh Use
1.
Poulose  BK, Shelton  J, Phillips  S,  et al.  Epidemiology and cost of ventral hernia repair: making the case for hernia research. Hernia. 2012;16(2):179-183.
PubMedArticle
2.
Muysoms  FE, Miserez  M, Berrevoet  F,  et al.  Classification of primary and incisional abdominal wall hernias. Hernia. 2009;13(4):407-414.
PubMedArticle
3.
Stroup  DF, Berlin  JA, Morton  SC,  et al.  Meta-analysis of observational studies in epidemiology: a proposal for reporting: Meta-analysis Of Observational Studies in Epidemiology (MOOSE) group. JAMA. 2000;283(15):2008-2012.
PubMedArticle
4.
Liberati  A, Altman  DG, Tetzlaff  J,  et al.  The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate healthcare interventions: explanation and elaboration. BMJ. 2009;339:b2700. doi:10.1136/bmj.b2700.
PubMedArticle
5.
Downs  SH, Black  N.  The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. J Epidemiol Community Health. 1998;52(6):377-384.
PubMedArticle
6.
Gasparrini  A, Armstrong  B, Kenward  MG.  Multivariate meta-analysis for non-linear and other multi-parameter associations. Stat Med. 2012;31(29):3821-3839.
PubMedArticle
7.
Arroyo  A, García  P, Pérez  F, Andreu  J, Candela  F, Calpena  R.  Randomized clinical trial comparing suture and mesh repair of umbilical hernia in adults. Br J Surg. 2001;88(10):1321-1323.
PubMedArticle
8.
Asolati  M, Huerta  S, Sarosi  G, Harmon  R, Bell  C, Anthony  T.  Predictors of recurrence in veteran patients with umbilical hernia: single center experience. Am J Surg. 2006;192(5):627-630.
PubMedArticle
9.
Berger  RL. Clapp  ML, Chu  C, Hicks  SC, Awad  SS, Liang  MK. Suture repair vs prolene hernia system for elective primary ventral hernia repairs. In Submission.
10.
Bowley  DM, Boffard  KD.  Penetrating lung hernia with pulmonary evisceration: case report. J Trauma. 2001;50(3):560-561.
PubMedArticle
11.
Eryilmaz  R, Sahin  M, Tekelioglu  MH.  Which repair in umbilical hernia of adults: primary or mesh? Int Surg. 2006;91(5):258-261.
PubMed
12.
Halm  JA, Heisterkamp  J, Veen  HF, Weidema  WF.  Long-term follow-up after umbilical hernia repair: are there risk factors for recurrence after simple and mesh repair. Hernia. 2005;9(4):334-337.
PubMedArticle
13.
Polat  C, Dervisoglu  A, Senyurek  G, Bilgin  M, Erzurumlu  K, Ozkan  K.  Umbilical hernia repair with the Prolene hernia system. Am J Surg. 2005;190(1):61-64.
PubMedArticle
14.
Sanjay  P, Reid  TD, Davies  EL, Arumugam  PJ, Woodward  A.  Retrospective comparison of mesh and sutured repair for adult umbilical hernias. Hernia. 2005;9(3):248-251.
PubMedArticle
15.
Stabilini  C, Stella  M, Frascio  M,  et al.  Mesh versus direct suture for the repair of umbilical and epigastric hernias: ten-year experience. Ann Ital Chir. 2009;80(3):183-187.
PubMed
16.
Aslani  N, Brown  CJ.  Does mesh offer an advantage over tissue in the open repair of umbilical hernias? a systematic review and meta-analysis. Hernia. 2010;14(5):455-462.
PubMedArticle
17.
Scott  N, Go  PM, Graham  P, McCormack  K, Ross  SJ, Grant  AM.  Open mesh vs non-mesh for groin hernia repair .Cochrane Database Syst Rev. 2011;(10):CD002197. doi:10.1002/14651858.CD002197.
PubMed
18.
den Hartog  D, Dur  AH, Tuinebreijer  WE, Kreis  RW.  Open surgical procedures for incisional hernias .Cochrane Database Syst Rev. 2008;(1):CD006438. doi:10.1002/14651858.CD006438.pub2.
PubMed
19.
Lau  H, Patil  NG.  Umbilical hernia in adults. Surg Endosc. 2003;17(12):2016-2020.
PubMedArticle
20.
Stylopoulos  N, Gazelle  GS, Rattner  DW.  A cost-utility analysis of treatment options for inguinal hernia in 1,513,008 adult patients. Surg Endosc. 2003;17(2):180-189.
PubMedArticle
21.
Cohn  LD, Becker  BJ.  How meta-analysis increases statistical power. Psychol Methods. 2003;8(3):243-253.
PubMedArticle
22.
Shadish  WR, Cook  TD, Campbell  DT. Experimental and Quasi-Experimental Designs for Generalized Causal Inference. Boston, MA: Houghton Mifflin; 2002.
23.
Riley  RD.  Multivariate meta-analysis: the effect of ignoring within-study correlation. J R Stat Soc. 2009;172(4):1-23.Article
Original Investigation
Association of VA Surgeons
May 2014

Comparison of Outcomes of Synthetic Mesh vs Suture Repair of Elective Primary Ventral HerniorrhaphyA Systematic Review and Meta-analysis

Author Affiliations
  • 1Department of Surgery, The University of Texas Health Sciences Center, Houston, Texas
  • 2Department of Surgery, Baylor College of Medicine, Houston, Texas
  • 3Department of Statistics, Dana Farber Cancer Institute, Boston, Massachusetts
  • 4Houston Veterans Affairs Health Services Research and Development Center for Excellence, Baylor College of Medicine, Houston Texas
JAMA Surg. 2014;149(5):415-421. doi:10.1001/jamasurg.2013.5014
Abstract

Importance  More than 350 000 ventral hernias are repaired in the United States annually, of which 75% are primary ventral hernias (eg, umbilical or epigastric hernias). Despite the volume, there is insufficient evidence to support the use of sutures vs mesh for primary ventral hernia repairs.

Objective  To compare suture vs mesh repairs for 3 outcomes: hernia recurrence, surgical site infection (SSI), and seromas.

Data Sources  Randomized controlled trials, case-control, and cohort studies were identified from OVID, PubMed, and reference lists from January 1, 1980, through June 1, 2012.

Study Selection  English-language studies with adult patients were eligible for review if there was mention of both suture and mesh techniques used during elective repair of a primary ventral hernia. Two study authors independently reviewed the 1492 articles originally identified and selected 9 for analysis. The Downs and Black 26-item checklist was used to critically assess the risk of bias.

Data Extraction  Year of publication, study design, inclusion and exclusion criteria, number of patients, follow-up duration, use of preoperative antibiotics, size of hernias repaired, age, body mass index (calculated as weight in kilograms divided by height in meters squared), American Society of Anesthesiologists grade, repair techniques, incidence of hernia recurrence, seroma, and SSI.

Data Extraction and Synthesis  Three separate univariate meta-analyses for each end point followed by a multivariate meta-analysis were performed. Across all 9 studies, there were 637 mesh repairs and 1145 suture repairs. The pooled mesh repairs demonstrated a 2.7% recurrence rate, 7.7% seroma rate, and 7.3% SSI rate The pooled suture repairs demonstrated an 8.2% recurrence rate, 3.8% seroma rate, and 6.6% SSI rate. On the basis of results from the multivariate meta-analysis, recurrences (log odds ratio , −1.04; 95% CI, −1.58 to −0.52) were more common with suture repair, whereas seromas (0.84; 0.27-1.41) and SSIs (0.65; 0.12-1.18) were more common with mesh repair.

Conclusions and Relevance  Mesh repair has a small reduction in recurrence rates compared with suture repairs for primary ventral hernias, but an increased risk of seroma and SSI was observed. Further high-quality studies are necessary to determine whether suture or mesh repair leads to improved outcomes for primary ventral hernias.

Quiz Ref IDMore than 350 000 ventral hernias are repaired in the United States annually, of which 75% are primary ventral hernias (nonincisional).1,2 To mitigate the risk of hernia recurrence that is associated with the use of suture repair techniques, mesh repair has become a popular alternative. Despite the strong trend toward the use of mesh repairs, particularly with large primary ventral hernias, there is insufficient quality data supporting this practice. In addition, outcomes of seroma formation and surgical site infection (SSI) are less commonly reported but are important outcomes associated with significant morbidity and cost. Furthermore, wound complications and seromas may be associated with increased rates of hernia recurrence.

This study assesses hernia recurrence, seroma formation, and SSI after 2 treatment options for hernia repair—mesh and suture. To appropriately account for the correlation between the multiple end points, 2 statistical techniques—a univariate meta-analysis that examines each complication independently and a multivariate meta-analysis that examines all 3 complications concurrently—are used.

Methods
Search Methods for the Identification of Studies

A literature search following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines and the Meta-analysis of Observational Studies in Epidemiology checklist for observational studies was performed with the MEDLINE database, using PubMed and OvidSP, with the following medical subject heading (MeSH) terms: ventral hernia and suture or mesh.3,4 These searches were restricted according to the following MeSH limits: (1) January 1, 1980, through June 1, 2012, (2) human, (3) adults 19 to 44 years and 45 years or older, and (4) English-language articles. A search of the references of captured articles was also performed. Titles, abstracts, and entire articles were reviewed by 2 independent reviewers (R.L.B. and M.K.L.), and discrepancies were resolved by consensus among the authors.

Inclusion and Exclusion Criteria

Quiz Ref IDArticles were eligible for review if there was mention of both suture and mesh techniques used during elective repair of a primary ventral hernia. Exclusion criteria included the following: description of a surgical technique only, only evaluated patients with cirrhosis, assessed emergency cases only, consisted of fewer than 10 patients in either study group (mesh or suture), consisted of laparoscopic cases only, included incisional hernias (including recurrent primary ventral hernias), or did not report comparative outcomes of SSI, hernia recurrence, or seroma formation.

Data Extraction

The following information was extracted from each article: year of publication, study type, inclusion and exclusion criteria, number of patients, follow-up duration, use of preoperative antibiotics, size of hernias repaired, age, body mass index (calculated as weight in kilograms divided by height in meters squared), American Society of Anesthesiologists grade, repair techniques, and incidence of hernia recurrence, seroma, and SSI.

All studies were graded for risk of study bias using the Downs and Black 26-item checklist for the assessment of methodologic quality that included the following: 10 variables for assessing quality of reporting, 3 for external validity, 7 for bias, and 6 for confounding.5 Two independent reviewers (R.L.B. and M.K.L.) reviewed and scored each study on a scale of 0 (lowest) to 26 (highest) and then gave a global grade: low, moderate, or high risk of bias. Reviewers were not masked, and studies were evaluated in no particular order. Discrepancies between scores were discussed and resolved between the reviewers.

Statistical Analysis

The statistical software R was used for the analysis of data.6 A univariate meta-analysis for each end point was performed to calculate the odds ratios (OR) with 95% CIs. A multivariate meta-analysis was performed to jointly estimate the log OR of mesh vs suture for the 3 end points: hernia recurrence, seroma, and SSI. Heterogeneity was assessed using the Higgins I2 statistic. The fixed-effects model was used throughout.

Results
Systematic Review

The results of the systematic review are shown in Figure 1. A total of 1492 potential citations were initially identified using the MeSH terms and limits. An evaluation of titles resulted in omission of 1384 articles with titles not related to primary hernia repair. Review of the remaining 108 article abstracts resulted in the exclusion of an additional 84 articles because of study design issues, unsuitable comparator groups, irrelevant outcomes, or included hernias not of interest. Of the 24 articles remaining, 15 were excluded because they had sample size issues, only evaluated patients with cirrhosis, or included incisional hernias. Nine articles met the inclusion and exclusion criteria and were included in the final analysis.

The characteristics of the 9 included articles are summarized in Table 1. The studies included consisted of prospective randomized control trials (n = 2), retrospective medical record reviews (n = 4), and prospective observational studies (n = 3). The use of preoperative antibiotics varied among the studies, with 1 study reporting a difference in use between suture and mesh repairs. The global risk of bias for the articles varied. After consensus among the reviewers, 7 articles had a high risk of bias and 1 article each had a medium and low risk of bias. Although the risk of bias varied because each article met the minimum criteria for inclusion, the articles were included in the meta-analysis.

Table 2 presents the extracted information for each article with respect to suture and mesh use. Quiz Ref IDThere were 1782 total cases, with 637 mesh repairs and 1145 suture repairs.

Univariate Meta-analysis

The univariate meta-analysis for recurrence included all 9 articles. The pooled recurrence rate was 2.7% (n = 17) for mesh repair and 8.2% (n = 94) for suture repair. With respect to recurrence, there was no suggestion of heterogeneity among the studies. The I2 test was 0% (P = .49), suggesting little variation among the included studies. The analysis of pooled data revealed that mesh repair was associated with a lower recurrence rate compared with suture repair (OR, 0.31; 95% CI, 0.18-0.52; P < .001). Only 1 study noted the interval from operative repair to hernia recurrence in its cohort (median, 28 months; range, 16-62 months)12 (Figure 2A).

Six studies were included in the analysis for seroma complication. The pooled seroma rate was 7.7% (n = 32) for mesh repair and 3.8% (n = 21) for suture repair. The I2 test was insignificant for heterogeneity among the articles (I2 = 0%, P = .48). The pooled OR was 2.27 (95% CI, 1.30-3.97; P = .004) for risk of seroma formation with mesh compared with suture repair. Patients undergoing mesh repair had an increased risk of developing a seroma complication (Figure 2B).

Seven studies evaluated SSI as a complication after primary ventral hernia repair using mesh or suture. The pooled SSI rate was 7.3% (n = 31) for mesh repair and 6.6% (n = 43) for suture repair. The resultant pooled univariate OR showed that mesh repair did not differ in SSI occurrences when compared with suture repair (OR, 1.53; 95% CI, 0.94-2.49; P = .08). However, analysis of heterogeneity revealed an I2 of 47.1% (P = .08), indicating that the studies were dissimilar (Figure 2C).

Multivariate Meta-analysis

Quiz Ref IDA multivariate meta-analysis was performed to jointly estimate the effect sizes. This meta-analysis incorporated the correlation of the estimates, which can be increased by borrowing strength from external studies. All 9 articles were included in the analysis. Recurrence was associated with suture repair (log OR, −1.05; 95% CI, −1.58 to −0.52; P <.001), whereas risk of seroma formation and SSI occurrence was associated with mesh repair (0.84; 0.27-1.41; P <.004; and 0.65; 0.12-1.18; P = .02, respectively). When assessing heterogeneity, an I2 of 16.8% (P = .25) was found, indicating that the studies were not heterogeneous.

Discussion

Primary ventral hernias are distinguishable from incisional hernias and warrant independent research to guide best practice. Using a multivariate meta-analysis, this study found that the use of mesh in primary ventral hernia repairs resulted in fewer hernia recurrences but more seromas and SSIs.

Only 1 other meta-analysis has assessed the morbidity associated with mesh vs suture repair of primary ventral hernias. The meta-analysis by Aslani and Brown16 found that mesh offered a reduction in recurrence rates but no difference in wound complications in the repair of primary umbilical hernias. However, this meta-analysis failed to exclude studies with incisional hernias, including recurrent hernias. Incisional hernias result from failure of a previous incision, indicating a difference in cause when compared with primary ventral hernias. This meta-analysis also included studies that involved cases in patients requiring emergency surgery and incarcerated patients, which are vastly different from elective repair. In addition, wound infections, seroma formation, and hematoma formation were combined into 1 category: wound complications. The test for heterogeneity when assessing the association between wound complications and repair type in cohort studies was I2 = 47% for the meta-analysis by Aslani and Brown, indicating that the studies were heterogeneous.16 Two Cochrane reviews that assessed mesh vs suture repair found mesh to be associated with lower hernia recurrence in both inguinal and incisional hernia repairs. In the setting of inguinal hernia repairs, one of the reviews did not find a difference in the occurrences of seromas and wound infections, whereas the other review found that mesh use resulted in an increase in wound infections in incisional hernias.17,18 Aside from these studies, analysis of the effects of mesh and suture use in the setting of primary ventral hernia repairs has not been analyzed adequately.

The studies included in our analysis used several different techniques for repair, particularly a simple interrupted suture or the Mayo technique for suture repair and polypropylene mesh placed in different locations. Although there are many kinds of mesh, most studies included in this analysis used polypropylene. The reason for this use was not clearly stated in the studies, but polypropylene is relatively economical and easy to handle, making it a common choice for hernia repairs. In some studies, a mesh plug was also used. When comparing the different techniques for mesh placement, the onlay (prefascial) technique has resulted in fewer recurrences, but the results of the analysis were not significant.18 In a study by Lau and Patil,19 simple suture repair resulted in a higher recurrence rate when compared with the Mayo technique. In this meta-analysis, the different techniques for suture and mesh repair were too varied to allow for adequate analysis.

The results of this meta-analysis have important implications for clinical practice. The use of mesh may result in an increase in seroma formation and SSI risk, but use of mesh may be more beneficial, especially in recurrence. A cost-analysis of treatments for inguinal hernias found that mesh proved to be more cost-effective in the long run. In addition, this study found that the recurrence rate was highly correlated with the cost-effectiveness ratio of the differing techniques.20 With the increased risk of SSIs and seromas, the cost-effectiveness of mesh repair with marginal recurrence rates may be mitigated compared with other repair types.

The use of more advanced statistical techniques to combine information across several studies is being sought to establish consensus quantitative evidence that may contribute to hypothesis generation. Because of its ability to synthesize information to assist in decision making, the meta-analytic technique has been used in several different disciplines. A meta-analysis has the ability to detect associations that are typically not seen in individual studies because of low statistical power.21 In addition, the meta-analytic technique has the advantage of making results more generalizable, thereby improving the external validity of an association.22 Typically, studies use a univariate meta-analysis to assess the effect size across studies for a single outcome of interest. However, in clinical practice, there are numerous outcomes that may be the result of a technique, and these outcomes may correlate. As such, to more appropriately understand the relationship between an intervention and its outcomes, a multivariate meta-analysis is used. A multivariate meta-analysis allows for a pooled statistic for each end point to be calculated while accounting for any correlation between end points and discrepancies that may exist within a study and among different studies.23

This study uses 2 statistical approaches to analyze the morbidity of mesh and suture repairs of primary ventral hernias. In the first approach, we analyzed the results using a standard univariate meta-analysis for each morbidity independently. From this, we found mesh to be associated with less recurrence but more seroma formations. The univariate analysis did not find a difference in SSIs between mesh and suture repairs. In the second approach, the multivariate meta-analysis found that SSI was associated with mesh use. Using a multivariate meta-analysis allowed us to corroborate the findings from other studies by ruling out possible interaction among the 3 most common morbidities assessed in the literature after mesh and suture repair of primary ventral hernias.

Quiz Ref IDThis meta-analysis included only 1 study that rated low on the Downs and Black checklist. Most of the studies had a high degree of risk of bias, lending to the possibility that the meta-analysis may not appropriately capture valuable individual patient data. Although this may be the case, our results are aligned with the current literature.

Hernia size is likely to be a confounder for the choice of mesh or suture repair, but the studies included did not uniformly report on hernia size. Therefore, a subgroup analysis was not possible.

Conclusions

The results of our multivariate meta-analysis support previous reports that found that the use of mesh for primary ventral hernias is associated with a lower recurrence risk. In addition, mesh use resulted in an increased risk of seroma formation and SSIs compared with suture repair. Despite being one of the most common surgical procedures, the level of evidence available on repair of primary ventral hernias remains poor with largely level II to IV data. Additional prospective randomized control trials are warranted to corroborate the findings of this meta-analysis.

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Article Information

Accepted for Publication: July 2, 2013.

Corresponding Author: Mike K. Liang, MD, Department of Surgery, The University of Texas Health Sciences Center, Lyndon B. Johnson Hospital, 5656 Kelley Street, Houston, TX 77026 (mkliang@yahoo.com and mike.liang@uth.tmc.edu).

Published Online: February 19, 2014. doi:10.1001/jamasurg.2013.5014.

Author Contributions: Dr Liang had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Nguyen, Berger, Li, Liang.

Acquisition of data: Berger, Li, Liang.

Analysis of data: Nguyen, Berger, Hicks, Davila, Li, Kao, Liang.

Drafting of the manuscript: Nguyen, Berger, Hicks, Liang.

Critical revision of the manuscript for important intellectual content: Nguyen, Berger, Davila, Li, Kao, Liang.

Statistical Analysis: Nguyen, Berger, Hicks, Davila, Liang.

Administrative, technical, or material support: Nguyen, Li, Liang.

Study supervision: Liang.

Conflict of Interest Disclosures: Dr Liang is currently receiving a grant from Lifecell and Acell. No other disclosures were reported.

Previous Presentation: Presented at the Annual Meeting of the Association of Veterans Affairs Surgeons; April 22, 2013; Milwaukee, Wisconsin.

References
1.
Poulose  BK, Shelton  J, Phillips  S,  et al.  Epidemiology and cost of ventral hernia repair: making the case for hernia research. Hernia. 2012;16(2):179-183.
PubMedArticle
2.
Muysoms  FE, Miserez  M, Berrevoet  F,  et al.  Classification of primary and incisional abdominal wall hernias. Hernia. 2009;13(4):407-414.
PubMedArticle
3.
Stroup  DF, Berlin  JA, Morton  SC,  et al.  Meta-analysis of observational studies in epidemiology: a proposal for reporting: Meta-analysis Of Observational Studies in Epidemiology (MOOSE) group. JAMA. 2000;283(15):2008-2012.
PubMedArticle
4.
Liberati  A, Altman  DG, Tetzlaff  J,  et al.  The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate healthcare interventions: explanation and elaboration. BMJ. 2009;339:b2700. doi:10.1136/bmj.b2700.
PubMedArticle
5.
Downs  SH, Black  N.  The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. J Epidemiol Community Health. 1998;52(6):377-384.
PubMedArticle
6.
Gasparrini  A, Armstrong  B, Kenward  MG.  Multivariate meta-analysis for non-linear and other multi-parameter associations. Stat Med. 2012;31(29):3821-3839.
PubMedArticle
7.
Arroyo  A, García  P, Pérez  F, Andreu  J, Candela  F, Calpena  R.  Randomized clinical trial comparing suture and mesh repair of umbilical hernia in adults. Br J Surg. 2001;88(10):1321-1323.
PubMedArticle
8.
Asolati  M, Huerta  S, Sarosi  G, Harmon  R, Bell  C, Anthony  T.  Predictors of recurrence in veteran patients with umbilical hernia: single center experience. Am J Surg. 2006;192(5):627-630.
PubMedArticle
9.
Berger  RL. Clapp  ML, Chu  C, Hicks  SC, Awad  SS, Liang  MK. Suture repair vs prolene hernia system for elective primary ventral hernia repairs. In Submission.
10.
Bowley  DM, Boffard  KD.  Penetrating lung hernia with pulmonary evisceration: case report. J Trauma. 2001;50(3):560-561.
PubMedArticle
11.
Eryilmaz  R, Sahin  M, Tekelioglu  MH.  Which repair in umbilical hernia of adults: primary or mesh? Int Surg. 2006;91(5):258-261.
PubMed
12.
Halm  JA, Heisterkamp  J, Veen  HF, Weidema  WF.  Long-term follow-up after umbilical hernia repair: are there risk factors for recurrence after simple and mesh repair. Hernia. 2005;9(4):334-337.
PubMedArticle
13.
Polat  C, Dervisoglu  A, Senyurek  G, Bilgin  M, Erzurumlu  K, Ozkan  K.  Umbilical hernia repair with the Prolene hernia system. Am J Surg. 2005;190(1):61-64.
PubMedArticle
14.
Sanjay  P, Reid  TD, Davies  EL, Arumugam  PJ, Woodward  A.  Retrospective comparison of mesh and sutured repair for adult umbilical hernias. Hernia. 2005;9(3):248-251.
PubMedArticle
15.
Stabilini  C, Stella  M, Frascio  M,  et al.  Mesh versus direct suture for the repair of umbilical and epigastric hernias: ten-year experience. Ann Ital Chir. 2009;80(3):183-187.
PubMed
16.
Aslani  N, Brown  CJ.  Does mesh offer an advantage over tissue in the open repair of umbilical hernias? a systematic review and meta-analysis. Hernia. 2010;14(5):455-462.
PubMedArticle
17.
Scott  N, Go  PM, Graham  P, McCormack  K, Ross  SJ, Grant  AM.  Open mesh vs non-mesh for groin hernia repair .Cochrane Database Syst Rev. 2011;(10):CD002197. doi:10.1002/14651858.CD002197.
PubMed
18.
den Hartog  D, Dur  AH, Tuinebreijer  WE, Kreis  RW.  Open surgical procedures for incisional hernias .Cochrane Database Syst Rev. 2008;(1):CD006438. doi:10.1002/14651858.CD006438.pub2.
PubMed
19.
Lau  H, Patil  NG.  Umbilical hernia in adults. Surg Endosc. 2003;17(12):2016-2020.
PubMedArticle
20.
Stylopoulos  N, Gazelle  GS, Rattner  DW.  A cost-utility analysis of treatment options for inguinal hernia in 1,513,008 adult patients. Surg Endosc. 2003;17(2):180-189.
PubMedArticle
21.
Cohn  LD, Becker  BJ.  How meta-analysis increases statistical power. Psychol Methods. 2003;8(3):243-253.
PubMedArticle
22.
Shadish  WR, Cook  TD, Campbell  DT. Experimental and Quasi-Experimental Designs for Generalized Causal Inference. Boston, MA: Houghton Mifflin; 2002.
23.
Riley  RD.  Multivariate meta-analysis: the effect of ignoring within-study correlation. J R Stat Soc. 2009;172(4):1-23.Article
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