Key points from the evidence

Scottish Health Technologies Group (SHTG)
Healthcare Improvement Scotland
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Synthetic mesh versus non-mesh repair in all adults

  • Meta-analyses comparing mesh with non-mesh repair found a statistically significant reduction in hernia recurrence rate and an increased risk of seroma formation with mesh repair.
    • Ventral hernia: hernia recurrence relative risk (RR) 0.13, 95% confidence interval (CI) 0.04 to 0.39, p=0.0003.
    • Incisional hernia: hernia recurrence RR 0.44, 95% CI 0.31 to 0.62, p<0.00001; seroma RR 2.88, 95% CI 1.52 to 5.42, p<0.001.
    • Umbilical hernia: hernia recurrence RR 0.48, 95% CI 0.30 to 0.77, p=0.002; seroma RR 2.37, 95% CI 1.45 to 3.87, p<0.001.
    • Inguinal hernia: hernia recurrence RR 0.46, 95% CI 0.26 to 0.80, p=0.0055; seroma RR 1.63, 95% CI 1.03 to 2.59, p=0.038.
  • Chronic pain was reported as an outcome in comparisons of mesh and non-mesh repair in patients with an umbilical or inguinal hernia.
    • Umbilical hernia: no meta-analyses reported on chronic pain due to high heterogeneity. Of four primary studies reporting chronic pain at median follow-up of 5 years, two found less chronic pain with mesh repair, one found more chronic pain with mesh repair, and one study found no difference in chronic pain between mesh and non-mesh repair.
    • Inguinal hernia: one meta-analysis found a statistically significant reduction in the odds of persistent pain 1 year after surgery with mesh repair (odds ratio (OR) 0.60, 95% CI 0.42 to 0.84) while another found no statistically significant differences at median follow-up of 1 year.
  • A UK cost-effectiveness study comparing open mesh repair with non-mesh repair of inguinal hernias demonstrated that, over a 5 year time horizon, open mesh repair resulted in fewer people experiencing hernia recurrence or persistent pain, and more time spent performing usual activities, all based on a cumulatively lower cost (mean saving £134, 95% CI £81 to
    £192).
  • Gaps in the published literature on mesh compared with non-mesh hernia repair were:
    • No secondary literature on repair of femoral hernias.
    • No secondary literature on chronic pain outcomes in primary ventral or incisional hernia repair.
    • No cost-effectiveness evidence on primary ventral, incisional, or umbilical hernias.

Biological versus synthetic mesh repair in all adults

  • Ventral hernia: a meta-analysis with high heterogeneity (I2=82%) compared biological mesh with synthetic mesh and found no statistically significant differences in hernia recurrence rates: OR 0.76, 95% CI 0.21 to 2.76, p=0.67. Wound infection was statistically significantly less likely in patients treated with biological mesh: OR 0.18, 95% CI 0.09 to 0.37, p<0.00001.
  • Inguinal hernia: a meta-analysis comparing biological mesh with synthetic mesh in men found no statistically significant differences in hernia recurrence risk (OR 2.15, 95% CI 0.39 to 11.74, p=0.38) but an increased risk of seroma with biological mesh (OR 2.67, 95% CI 1.12 to 6.35, p=0.03).
  • A meta-analysis found no statistically significant differences in chronic pain lasting more than 3 months in comparisons of biological and synthetic mesh repair of groin hernias: OR 0.54, 95% CI 0.29 to 1.02, p=0.06.
    Economic studies were identified that compared biological and synthetic mesh for primary ventral and incisional hernias.
    • Ventral hernia: two cost-utility analyses, that both took a societal perspective (direct hospital costs and indirect costs to patients), estimated that synthetic mesh was more effective and less costly than biological mesh in clean-contaminated primary ventral hernia repairs over a time horizon of 5 and 30 years, respectively.
    • Incisional hernia: a cost comparison estimated direct medical costs associated with treatment using biological mesh to be statistically significantly more expensive (£14,247 versus £4,364) for incisional hernia repair at 1-year follow-up. These findings should be interpreted with caution since only complex cases were assigned to receive biological mesh.
  • Gaps in the published literature on biological mesh compared with synthetic mesh were:
    • No secondary evidence for umbilical or femoral hernia repairs.
    • No secondary evidence based on comparative studies in patients with incisional hernias.
    • No cost-effectiveness evidence on inguinal, femoral, or umbilical hernias.

Laparoscopic versus open mesh repair in all adults

  • In comparisons of laparoscopic and open mesh repair, a pairwise meta-analysis and a network meta-analysis found no significant differences in hernia recurrence rates and an increased risk of surgical site infection with open mesh repair.
    • Ventral hernia: hernia recurrence rate OR 0.95, 95% CI 0.46 to 1.98, p=0.89; surgical site infection OR 4.17, 95% CI 2.03 to 8.55, p<0.001.
    • Incisional hernia: hernia recurrence risk OR 1.14, 95% CI 0.81 to 1.60, p=0.47; surgical site infection OR 5.16, 95% CI 2.79 to 9.57, p<0.001.
    • Inguinal hernia (81.5% male patients): hernia recurrence risk (transabdominal preperitoneal (TAPP) versus open) RR 0.96, 95% credible interval (CrI) 0.57 to 1.51; hernia recurrence (totally extraperitoneal (TEP) versus open) RR 1.0, 95% CrI 0.65 to 1.61; wound infection risk (TEP versus open) OR 0.33, 95% CrI 0.09 to 0.81.
  • Chronic pain was reported as an outcome in comparisons of laparoscopic and open mesh repair in patients with a ventral or inguinal hernia.
    • Ventral hernia: in a meta-analysis of two studies, there was no statistically significant difference in chronic pain (undefined) following laparoscopic versus open repair.
    • Inguinal hernia (81.5% male patients): a network meta-analysis found no significant differences in chronic pain (undefined) for comparisons of open, TAPP and TEP inguinal hernia repair.
  • Evidence comparing the cost of laparoscopic versus open mesh repair reached varying conclusions.
    • Ventral hernia: a cost comparison estimated laparoscopic repair to be associated with a reduction in costs of £2,481 (p<0.001) 1 year after surgery.
    • : a cost-minimisation analysis estimated that TEP repair was associated with increased costs of up to £691 (p<0.01) compared with open repair, 5 years after surgery. A cost comparison estimated TEP and TAPP repair techniques to be £308 and £140 less costly relative to open mesh repair (p<0.001 and p<0.05, respectively).
  • Gaps in the published literature on laparoscopic compared with open hernia repair were:
    • No secondary evidence for umbilical or femoral hernias.
    • No cost-effectiveness evidence for primary umbilical, incisional, or primary femoral hernias.

Mesh fixation techniques in all adults

  • Secondary evidence compared mesh fixation techniques including permanent tacks, fibrin glue, suture fixation, permanent tacks plus suture fixation, staples, absorbable tacks, self- gripping mesh, and no fixation.
    • Ventral hernia (laparoscopic repair): a network meta-analysis reported no significant differences in hernia recurrence between permanent tack fixation, fibrin glue, suture fixation, or permanent tacks plus suture fixation. Lower recurrence rates were found for permanent tacks compared with absorbable tacks (RR 1.37, 95% CI 1.03 to 1.81).
    • Inguinal hernia (open repair): a network meta-analysis found no significant differences in hernia recurrence for comparisons of fibrin glue or suture fixation with self-gripping mesh.
    • Inguinal hernia (laparoscopic repair): a network meta-analysis found no differences in hernia recurrence between no fixation, absorbable tack fixation, suture fixation, and glue fixation, during TEP repair of inguinal hernias. Pairwise meta-analysis of fibrin glue versus staple fixation in TAPP inguinal hernia repair found no statistically significant differences in hernia recurrence.
  • Chronic pain was reported as an outcome in comparisons of mesh fixation for ventral and groin hernia repair.
    • Ventral hernia: no statistically significant differences in chronic pain at 3–6 months follow-up were reported in meta-analyses comparing tack and suture mesh fixation, or absorbable and non-absorbable tack fixation.
    • Groin hernia: two network meta-analyses found no significant differences in chronic pain at 1-year follow-up in comparisons of mesh fixation techniques.
  • Gaps in the published literature comparing mesh fixation techniques were:
    • No secondary evidence for umbilical or femoral hernia repair.
    • No cost-effectiveness evidence on any hernia type.

Synthetic mesh safety in all adults

  • In 2015–2020 Public Health Scotland recorded 161 cases of surgical mesh removal, 55 in women and 106 in men. The average annual rate of mesh removal was 32 procedures during this period. The reasons for mesh removal were not reported.
  • A meta-analysis of cohort studies found that mesh-related infections occurred in 7.2% of ventral hernia repairs (119/1,657) and 0.3% of groin hernia repairs (2/761). Statistically significant risk factors for mesh-related infections included smoking, needing an emergency repair, increased patient age, and higher American Society of Anaesthesiologists (ASA) score.

Patient and social aspects (all adults)

  • A qualitative study in patients who had a ventral hernia repair described hernias and hernia repairs as having an impact on activities of daily living including lifting heavy objects, working, engaging with children, and socialising.
  • A survey of patients presenting for hernia surgery in the USA found that patient perceptions of mesh were most strongly influenced by the media (37%) and personal experience of prior surgeries (35%).
  • The information needs of patients centred around the benefits and risks of mesh, and hernia management options. Patient views on the value of online information seeking varied, with some finding it informed decision making while others found it increased anxiety.
  • Two cohort studies found that women were statistically significantly less likely to receive laparoscopic groin hernia repair compared with men: 33% women versus 62.6% men (p=0.001); OR 0.70, 95% CI 0.67 to 0.73 (p<0.001). Neither study was conducted in the UK nor could either study offer an explanation for why women were less likely to receive laparoscopic hernia repairs.
  • SHTG conducted a 5-week engagement exercise in April 2021, using a survey to gather the experiences of patients in Scotland who had a hernia repair. The results of this exercise are reported in a supplement to this review.

Outcomes of hernia repair in women

  • A registry study (8,138 matched pairs) in patients who had an incisional hernia repair found that women were more likely than men to experience intra-operative complications and chronic pain at 1-year follow-up.
  • Two systematic reviews of mainly single-arm observational studies found that groin hernia recurrence was lower in women after laparoscopic hernia repair compared with open repair. Two comparative observational studies within these systematic reviews found no difference in groin hernia recurrence between mesh and non-mesh repair in women.
  • No studies reported on sex-specific effects or outcomes in women who had a primary ventral or primary umbilical hernia.

Editorial Information

Author email(s): his.shtg@nhs.scot.