Elsevier

The Lancet

Volume 390, Issue 10094, 5–11 August 2017, Pages 567-576
The Lancet

Articles
Prevention of incisional hernia with prophylactic onlay and sublay mesh reinforcement versus primary suture only in midline laparotomies (PRIMA): 2-year follow-up of a multicentre, double-blind, randomised controlled trial

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Summary

Background

Incisional hernia is a frequent long-term complication after abdominal surgery, with a prevalence greater than 30% in high-risk groups. The aim of the PRIMA trial was to evaluate the effectiveness of mesh reinforcement in high-risk patients, to prevent incisional hernia.

Methods

We did a multicentre, double-blind, randomised controlled trial at 11 hospitals in Austria, Germany, and the Netherlands. We included patients aged 18 years or older who were undergoing elective midline laparotomy and had either an abdominal aortic aneurysm or a body-mass index (BMI) of 27 kg/m2 or higher. We randomly assigned participants using a computer-generated randomisation sequence to one of three treatment groups: primary suture; onlay mesh reinforcement; or sublay mesh reinforcement. The primary endpoint was incidence of incisional hernia during 2 years of follow-up, analysed by intention to treat. Adjusted odds ratios (ORs) were estimated by logistic regression. This trial is registered at ClinicalTrials.gov, number NCT00761475.

Findings

Between March, 2009, and December, 2012, 498 patients were enrolled to the study, of whom 18 were excluded before randomisation. Therefore, we included 480 patients in the primary analysis: 107 were assigned primary suture only, 188 were allocated onlay mesh reinforcement, and 185 were assigned sublay mesh reinforcement. 92 patients were identified with an incisional hernia, 33 (30%) who were allocated primary suture only, 25 (13%) who were assigned onlay mesh reinforcement, and 34 (18%) who were assigned sublay mesh reinforcement (onlay mesh reinforcement vs primary suture, OR 0·37, 95% CI 0·20–0·69; p=0·0016; sublay mesh reinforcement vs primary suture, 0·55, 0·30–1·00; p=0·05). Seromas were more frequent in patients allocated onlay mesh reinforcement (34 of 188) than in those assigned primary suture (five of 107; p=0·002) or sublay mesh reinforcement (13 of 185; p=0·002). The incidence of wound infection did not differ between treatment groups (14 of 107 primary suture; 25 of 188 onlay mesh reinforcement; and 19 of 185 sublay mesh reinforcement).

Interpretation

A significant reduction in incidence of incisional hernia was achieved with onlay mesh reinforcement compared with sublay mesh reinforcement and primary suture only. Onlay mesh reinforcement has the potential to become the standard treatment for high-risk patients undergoing midline laparotomy.

Funding

Baxter; B Braun Surgical SA.

Introduction

Incisional hernia is one of the most frequent long-term complications after abdominal surgery, with an incidence of 5–20% in the general patient population. However, in high-risk patients, the incidence of incisional hernia can increase to more than 30%.1, 2, 3 Obese individuals (ie, those with a body-mass index [BMI] ≥30 kg/m2) and people with abdominal aortic aneurysm are especially high-risk groups. Patients with abdominal aortic aneurysm are at risk because of an underlying connective tissue disorder, caused partly by dysregulation of collagen type 1 and 3; this impairment probably has an important role in the pathogenesis of distension of the aorta and in formation of incisional hernia in patients after median laparotomy.4 Individuals with obesity or a BMI equal to or higher than 27 kg/m2 have a more than 30% chance of developing incisional hernia after median laparotomy.5 This group of patients are believed to have a higher intra-abdominal pressure, which can cause higher tension on abdominal wall sutures. However, this pressure might not be the only contributing factor: obesity is also associated with wound-healing complications due to decreased vascularity of adipose tissue, leading to local hypoxia. In hypoxic wounds, the synthesis of mature collagen is impaired, resulting in weaker tissue and a deficiency in the overall healing process. In wound healing, other known risk factors play an important part—eg, malignant disease, parastomal hernia, wound infection, and smoking.6, 7, 8, 9, 10

Incisional hernia can cause morbidity (eg, pain) and can have a negative effect on patients' quality of life and body image.11, 12, 13 Furthermore, there is a risk of obstruction and strangulation of the bowel with perforation and possible mortality as a result. For these reasons, repair of incisional hernia is a surgical procedure that is done frequently. However, even though repair with mesh reinforcement has lower risk of recurrence compared with primary suture, the cumulative 10-year incidence is 32%, which is still too high.14, 15 Use of laparoscopic techniques has not yielded better results with respect to recurrence of incisional hernia.16, 17, 18 Incisional hernia not only has a large effect in medicine but also has a great socioeconomic effect. Therefore, prevention of incisional hernia is of paramount importance: it will lead to reduction of disease and is, thus, cost-effective.

Research in context

Evidence before this study

The European Hernia Society has developed guidelines on closure of abdominal wall incisions. Although prophylactic mesh reinforcement is suggested for an elective midline laparotomy in high-risk patients (ie, those with an aneurysm of the abdominal aorta or who are obese [body-mass index ≥30 kg/m2), to reduce incisional hernias, evidence for this approach is weak. The Guidelines Development Group has suggested larger trials are needed to make a strong recommendation for this strategy. However, it is unclear which mesh position (onlay or sublay) leads to a lower occurrence of incisional hernias. We did a systematic literature search up to July, 2016, with the keywords “incisional hernia”, “prophylactic”, “prevention”, “onlay”, “sublay”, and “mesh”. We did not restrict our search by language. Three researchers reviewed all records independently. We included prospective randomised controlled trials that enrolled patients aged 18 years or older undergoing midline laparotomy for all indications, with any type of mesh and mesh position. We evaluated 12 randomised controlled trials, with high heterogeneity among studies. Incisional hernia arose less frequently when a prophylactic mesh was placed during midline laparotomy. Occurrence of seromas was highest in patients who underwent mesh reinforcement. Individuals in whom a mesh was placed during laparotomy seemed to have a higher risk of developing a surgical-site infection compared with those without a mesh.

Added value of this study

Compared with previous studies, the PRIMA randomised controlled trial had three arms to compare onlay mesh reinforcement, sublay mesh reinforcement, and primary suture. Onlay mesh reinforcement had a stronger and more significant effect on prevention of incisional hernia than did sublay mesh reinforcement. Moreover, the frequency of surgical-site infections was not increased with onlay mesh reinforcement.

Implications of all the available evidence

The PRIMA trial provides strong evidence in favour of onlay mesh reinforcement for prevention of incisional hernia in high-risk patients undergoing midline laparotomy. This finding is important because onlay placement of a mesh is an easier surgical technique than is sublay mesh reinforcement. Therefore, this approach could be adapted readily, not only by surgeons but also by urologists and gynaecologists, who also perform midline laparotomies. Closure of laparotomy with onlay mesh reinforcement has the potential to become the standard treatment in high-risk groups.

Many studies have evaluated different types of incision, suture materials, and closure techniques to reduce the incidence of incisional hernia.19, 20, 21 Horizontal incisions and laparoscopy, or endovascular aneurysm repair (EVAR), in patients with abdominal aortic aneurysm are well-known surgical techniques that minimise the risk of incisional hernia. In each patient undergoing surgery, the best available technique should be considered. However, for several individuals, conventional laparotomy is unavoidable. Until now, no adequate method or gold standard to prevent incisional hernia has been reported for people undergoing midline laparotomy. Patients at particular high risk of incisional hernia, including those with abdominal aortic aneurysm and high BMI, might benefit most from prevention.22, 23, 24, 25 In 1995, Pans and colleagues26 did a prospective study to compare patients undergoing surgery for morbid obesity with or without intraperitoneal polyglactin mesh. No difference in incidence of incisional hernia was noted between the two groups.26 Several randomised and non-randomised prospective studies have been done to investigate how incisional hernia can be prevented. Currently, no level 1 evidence is available. The quality of published randomised studies is low and there is no consensus about the mesh position in the abdominal wall that should be used.27, 28

We initiated the PRIMA trial (PRImary Mesh closure of Abdominal midline wounds) in 2009 with the aim to investigate prophylactic mesh reinforcement in high-risk groups (ie, patients with abdominal aortic aneurysm or a BMI ≥27 kg/m2).29, 30 We also aimed to assess which mesh position in the abdominal wall should be used to prevent incisional hernia. The primary aim of the PRIMA trial was to study the effectiveness of prophylactic mesh reinforcement to prevent incisional hernia.

Section snippets

Study design and patients

The PRIMA trial is an international, multicentre, double-blind, randomised controlled trial. The study methods and initial (short-term) results of the PRIMA trial have been described previously,29 and the trial protocol has been published elsewhere.30 The medical ethics committee of the Erasmus University Medical Centre in Rotterdam approved the trial; we also obtained approval from the local ethics committees of the participating hospitals.

We selected patients from 11 hospitals in Austria,

Results

Between March, 2009, and December, 2012, 498 patients were enrolled to the study (figure). 18 individuals were excluded because they either withdrew informed consent (n=3), did not have midline incision (n=8), had already presented with incisional hernia (n=3), or for other reasons (n=4). Of the 480 included patients, 150 (31%) patients had an abdominal aortic aneurysm and 330 (69%) individuals had a BMI of 27 kg/m2 or greater. At randomisation, 107 patients were assigned closure by primary

Discussion

The findings of the PRIMA trial show that onlay mesh reinforcement significantly reduced the incidence of incisional hernia after midline laparotomy in patients at high risk for incisional hernia (ie, those with abdominal aortic aneurysm or a BMI ≥27 kg/m2). Sublay mesh reinforcement did not have a significant effect on the incidence of incisional hernia compared with primary suture. Although the absolute difference in incidence of incisional hernia between onlay and sublay mesh reinforcement

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