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SYSTEMATIC REVIEW PROTOCOLS

Hernioplasty using low-cost mesh compared to surgical mesh in low- and middle-income countries: a systematic review protocol

Vaska, Ashish Immanuel1,2; Munn, Zachary1; Nagra, Sonal2; Barker, Timothy Hugh2

Author Information
doi: 10.11124/JBISRIR-D-19-00186
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Abstract

Introduction

Abdominal wall hernias are a protrusion of the abdominal contents, typically bowel or fat, through a muscular or fascial defect.1 The most common are groin hernias, that is, inguinal and femoral hernias, and inguinal hernia repair forms a significant part of global general surgical caseloads,2,3 with millions of repairs conducted worldwide annually.4 Hernias cause pain, reduce mobility and employability, and can result in mortality if strangulation (that is, entrapment and subsequent ischemic compromise of bowel with the hernia) occurs. The gold standard for hernia repair is the tension free Lichtenstein mesh hernioplasty,5 most commonly utilizing a polypropylene only, or a combination polypropylene and absorbable material mesh.6 This repair has robust evidence supporting its use and is associated with lower rates of recurrence, shorter operating times,7 quicker postoperative recovery and return to work, and less pain than suture-only repairs.8

In low- and middle-income countries (LMICs), the burden of untreated inguinal hernia is high,9 with estimates of prevalence ranging from 3% to 30%.7,10,11 The high prevalence of inguinal hernias is a consequence of structural and patient level factors.

Structural factors encompass the absence of infrastructure, such as roads and hospitals, limiting access to care, budgetary prioritization of traditional public health problems such as maternal and child health and communicable diseases, and a lack of qualified health professionals to facilitate safe, timely surgery. Complication rates in hernia repair in LMICs have been reported to be as high as 21%, although this does reflect significant task-shifting to non-surgeons in order to increase access.12

Myriad patient level factors also limit access to timely hernia repair, including lack of health literacy regarding the potentially life-threatening complications associated with hernias,11 geographical distance and the challenge of travelling to a hospital for care,4,13 and the financial costs of surgery (both income lost and purchasing required for supplies for surgery and aftercare).14-18

In light of these barriers, hernias in LMICs are more frequently treated in emergent settings, presenting with bowel obstruction or strangulation, than hernias in high-income countries (HICs). Historical data suggests over 10% of all hernias treated in LMICs occur in patients with strangulation, and mortality rates for these patients are 90%;13 more recent data has found that 65% of all hernia repairs in Ghana occur emergently.4 Hernia repairs in LMICs are also far less likely to be repaired using mesh, with less than 5% of all repairs in Africa utilizing mesh.4 The cost of surgical polypropylene mesh is a significant barrier to its use, accounting for 40–50% of the total cost of operations in some cases.3,8 This cost comprises both the purchase price, which reflects the cost of research and development that medical product manufacturers must recover, and import tariffs.

Despite these limitations and challenges, elective inguinal hernia repair in LMICs has been shown to be cost-effective, and in terms of its public health impact, comparable to immunization and malaria prevention measures.19 The effect on disability adjusted life years (DALYs) is immense – if all symptomatic hernias in Ghana were repaired, five million DALYs would be averted.2 This combination of significant prevalence and a simple, cost- effective solution that averts serious morbidity renders hernia repair as a surgical priority in LMICs.19

In response to this need, and in order to facilitate access to best practice care, surgeons in LMICs have utilized other low-cost, commercially available, non-surgical meshes in hernia repair.11,20,21 These include mosquito netting of varying materials such as polyester, polyethylene, polypropylene and nylon, resterilized surgical meshes and indigenous products. The findings of these studies, typically uncontrolled intervention studies, suggest comparable short- and long-term outcomes for hernioplasty utilizing low-cost mesh, when compared with the published data for surgical mesh.8 The most important and commonly reported outcomes are postoperative pain and hernia recurrence.5 Postoperative infection, cost-effectiveness, patient and surgeon satisfaction, and issues with sterilization and safety of use of low-cost mesh have also been reported.17

A preliminary search of PROSPERO, MEDLINE, Cochrane Database of Systematic Reviews and JBI Database of Systematic Reviews and Implementation Reports was conducted which identified three previous systematic reviews, two of which include a meta-analysis, which evaluated the use of non-surgical mesh in hernia repair. Ahmad et al.7 and Patterson et al.,22 both of which incorporated meta-analyses, included randomized controlled trials using only sterilized mosquito netting, with both focusing on postoperative outcomes. Sørensen and Rosenberg8 conducted a limited review of the literature across three databases in 2012. All of these provide a helpful assessment of the literature and are positive about the use of mosquito netting in place of surgical mesh.

However, there are limitations to the extent of the review and analysis process as conducted by these authors, with relatively few databases included, relevant RCTs excluded, and the analysis confined to postoperative outcomes. Inclusion of mosquito net mesh broadly does not account for the varied materials that comprise mosquito net at the structural level, and there is a need to consider these at a more granular level. There is also a growing body of evidence published regarding the use of low-cost meshes other than mosquito netting, such as resterilized surgical meshes and indigenous products, and the outcomes of these alternative low-cost meshes have not been assessed.

The objective of this proposed systematic review and (if feasible) meta-analysis, is to assess outcomes after hernia repair using low-cost mesh in low- and middle-income countries. This will build on the extant reviews by conducting an up-to-date review of the literature, across a wider set of databases and gray literature sources, include low-cost mesh alternatives other than and including mosquito netting, and consider outcomes such as patient and surgeon preference, sterility and recurrence, alongside a more granular assessment of complication rates. This would assist clinicians in LMICs in their decision-making regarding use of low-cost mesh, in particular, identifying potential areas for improvement of practice with regards to sterility and mesh choice. It may also facilitate downward pressure on the purchase price of surgical mesh in LMICs at the health systems level.

Review question

What are the differences in surgical outcomes between hernioplasty using low-cost mesh and that using surgical mesh in adults undergoing elective hernioplasty in low- and middle-income countries?

Inclusion criteria

Participants

The review will consider studies that include adult patients undergoing elective inguinal hernia repair in low- and middle-income countries. Low-, lower-middle- and upper-middle-income countries as defined by the World Bank country classification list will be considered for inclusion.23

Specific exclusion criteria include patients presenting for emergent hernia repair.

Intervention

This review will consider studies that will evaluate low-cost mesh used in hernia repair, including non-surgical mesh such as mosquito net, resterilized surgical mesh and indigenous prostheses. The surgery may be performed by any surgeon, regardless of their training or level. There will be no exclusions based on the clinical setting for the surgery (i.e. tertiary hospital, district hospital), other than it needing to be performed in a LMIC.

Comparator

This review will consider studies that compare the intervention to hernia repair using surgical mesh.

Outcomes

This review will consider studies that include any of the following primary outcomes: rates of postoperative pain, wound infection (both superficial and deep), wound collection, both seroma and hematoma, and hernia recurrence.

Secondary outcomes include any of the following: patient and surgeon satisfaction, durability and sterility of mesh, and cost.

Outcome measurement and definitions

Postoperative pain will be measured based on patient report on any identified scale used preoperatively and postoperatively, or postoperatively only. Superficial wound infection is any infection not involving the mesh, and treated with antibiotic therapy or wound dressings; deep infection is that involving mesh and requiring long-term suppressive antibiotic therapy or mesh explantation. Wound collection is defined by either clinically detected collection not requiring draining, or spontaneous drainage of serous fluid (seroma) or blood (hematoma), or collection requiring drainage, either percutaneous or formal surgical drainage. Hernia recurrence is any recurrence of a groin hernia after mesh repair. Secondary outcomes such as patient and surgeon satisfaction will be assessed on any scale utilized by authors, durability and sterility will be assessed based on mechanical or histological analysis, and cost will be compared against surgical mesh available in the same context.

Types of studies

This review will consider only experimental study designs, either randomized or quasi-randomized (i.e. systematic but not random allocation) controlled trials, for inclusion.

Studies published in any language will be included. Studies published from 2000 to the present will be included to ensure that data reflects current practice.

Methods

The proposed systematic review will be conducted in accordance with the JBI methodology for systematic reviews of effectiveness.24

Search strategy

The search strategy will aim to locate both published and unpublished studies. An initial limited search of PubMed and Embase was undertaken to identify articles on the topic. The text words contained in the titles and abstracts of relevant articles, and the index terms used to describe the articles were used to develop a full search strategy for PubMed (see Appendix I). The search strategy, including all identified keywords and index terms, will be adapted for each included information source. The reference lists of all studies selected for critical appraisal will be screened for additional studies.

Information sources

Information sources will include electronic bibliographic databases, trial registers, search engines and if required, direct contact with researchers. Sources of unpublished studies and gray literature will include trial registers, institutional repositories and websites of relevant organizations, such as Operation Hernia. Hand searching of existing systematic reviews and identified relevant studies will be conducted in order to identify any further relevant original studies.

Electronic bibliographic databases to be searched are: PubMed, Embase, Scopus, Web of Science, and the Cochrane Library.

Gray literature and trial registers to be searched are: Cochrane Controlled Register of Trials (CENTRAL), ProQuest, Web of Science Conference Proceedings, MedNar, ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform.

Study selection

Following the search, all identified citations will be collated and uploaded into EndNote V9.1.1 (Clarivate Analytics, PA, USA) and duplicates removed. Titles and abstracts will then be screened by two independent reviewers for assessment against the inclusion criteria for the review. Potentially relevant studies will be retrieved in full and their citation details imported into the JBI System for the Unified Management, Assessment and Review of Information. The full text of selected citations will be assessed in detail against the inclusion criteria by two independent reviewers. Reasons for exclusion of full text studies that do not meet the inclusion criteria will be recorded and reported in the systematic review. Any disagreements that arise between the reviewers at each stage of the study selection process will be resolved through discussion, or with a third reviewer. The results of the search will be reported in full in the final systematic review and presented in a Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) flow diagram.25

Assessment of methodological quality

Eligible studies will be critically appraised by two independent reviewers at the outcome level for methodological quality in the review using version 2 of the Cochrane risk-of-bias tool for randomized trials (RoB 2).26 Authors of papers will be contacted to request missing or additional data for clarification, where required. Any disagreements that arise will be resolved through discussion, or with a third reviewer. The results of critical appraisal will be reported in narrative form and in a table.

All studies, regardless of the results of their methodological quality, will undergo data extraction and synthesis (where possible). The results of the critical appraisal will be used to inform the analysis and interpretation of the results, including dictating how strongly the final conclusions of the review will be put forward.

Data extraction

Data will be extracted from studies included in the review by two independent reviewers using Microsoft Excel (Redmond, Washington, USA) (see Appendix II).

The data extracted will include specific details about the populations, study methods, interventions, and outcomes of significance to the review objectives.

Any disagreements that arise between the reviewers will be resolved through discussion, or with a third reviewer. Authors of papers will be contacted to request missing or additional data, where required.

Data synthesis

Studies will, where possible, be pooled in statistical meta-analysis using RevMan V5.3 (Copenhagen: The Nordic Cochrane Centre, Cochrane). Effect sizes will be expressed as either relative risks (for dichotomous data) and weighted (or standardized) final post-intervention mean differences (for continuous data), and their 95% confidence intervals will be calculated for analysis. Heterogeneity will be assessed statistically using the standard chi-squared and I2 tests. Statistical analyses will be performed using a random-effects model to facilitate generalization of findings beyond the included studies (an assumption of distribution of effects), if there are more than five studies included in the meta-analysis.27 If there are fewer than five studies, a fixed-effects model will be considered, where appropriate.27

Sensitivity analysis may be conducted to test assumptions about particular meta-analytic models to use. Where statistical pooling is not possible, the findings will be presented in narrative form, including tables and figures to aid in data presentation, where appropriate. A funnel plot will be generated using RevMan V5.3 to assess publication bias if there are 10 or more studies included in the meta-analysis. Statistical tests for funnel plot asymmetry (Egger test, Begg test, Harbord test) will be performed, where appropriate.

Assessing certainty in the findings

The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach for grading the certainty of evidence will be followed,28 and a Summary of Findings (SoF) will be created using GRADEPro (McMaster University, ON, Canada). The SoF will present the following information, where appropriate: absolute risks for the treatment and control, estimates of relative risk, and a ranking of the certainty of the evidence based on the risk of bias, indirectness, inconsistency, imprecision and risk of publication bias of the review results. The outcomes reported in the SoF will be:

  • superficial wound infection
  • deep wound infection including mesh explantation
  • wound collection including seroma and hematoma
  • postoperative pain
  • hernia recurrence
  • surgeon satisfaction
  • patient satisfaction
  • sterility
  • durability.

Acknowledgments

This review will contribute toward a degree award for AIV.

Appendix I: Search strategy for PubMed

((((((“Hernia”[Mesh]) OR “Herniorrhaphy”[Mesh]) OR “Hernia/surgery”[Mesh])) AND (((((((((((Hernia[Title/Abstract]) OR Hernia repair[Title/Abstract]) OR Inguinal hernia[Title/Abstract]) OR Inguinal hernia repair[Title/Abstract]) OR Hernioplasty[Title/Abstract]) OR Mesh repair[Title/Abstract]) OR Lichenstein repair[Text Word]) OR Groin hernia[Text Word]) OR Groin hernia repair[Text Word]) OR Tension free repair[Text Word]) OR Herniorraphy[Text Word]))) AND (((((“Surgical Mesh”[Mesh]) OR “Mosquito Nets”[Mesh]) OR “Culicidae”[Mesh])) AND (((((((((((((((((mesh[Title/Abstract]) OR Mosquito net[Title/Abstract]) OR Mosquito net mesh[Text Word]) OR Low cost[Text Word]) OR Low-cost mesh[Text Word]) OR Hernia implants[Text Word]) OR Resterilized mesh[Text Word]) OR Sterilized mesh[Text Word]) OR Surgical mesh[Text Word]) OR Commercial mesh[Text Word]) OR Polypropylene[Text Word]) OR Polyethylene[Text Word]) OR Nylon[Text Word]) OR Polyester[Text Word]) OR Non-commercial mesh[Text Word]) OR Prosthesis[Text Word]) OR Low density polyethylene[Text Word]))

Search conducted on 09/04/2019; 9946 records identified.

Appendix II: Data extraction instrument

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Keywords:

Hernia repair; inguinal hernia; low-cost mesh; low- and middle-income countries; surgical mesh

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