In this blog, Kath Sansom, founder of the Sling the Mesh campaign, unpacks the findings of a medical device performance study into polypropylene mesh published by the Emergency Care Research Institute (ECRI) in the US. The document highlights significant gaps in evidence about the risk of complications associated with polypropylene (PP) surgical mesh.
PP mesh has been widely used in surgery for stress urinary incontinence (SUI) and transvaginal or transabdominal prolapse since the 1990s, and hernia repair since the 1950s. In spite of this long history, there is a surprising lack of research into the link between surgical mesh and autoimmune conditions.
Among the many complications reported by women who have had vaginal mesh surgery, autoimmune symptoms feature high on the list. One member of the Sling the Mesh Facebook group was recently looking for answers about her own autoimmune symptoms when she came across a Medical device material performance study polypropylene safety profile put together by the ECRI. This blog will look at the key issues that it highlights concerning surgical mesh research.
What did the ECRI report aim to find out?
Produced by US non-profit organisation the ECRI, on behalf of the FDA Center for Devices and Radiological Health (CDRH), the report looks at existing research literature about PP mesh degradation and physiological responses to PP mesh. The authors of the report conducted a systematic review of 158 articles that were selected for inclusion, to answer five questions posed by the FDA:
- What is the typical/expected local host response to polypropylene?
- Does the material elicit a persistent or exaggerated response that may lead to systemic signs or symptoms, beyond known direct toxicity problems?
- Are there any patient-related factors that may predict, increase, or decrease the likelihood and/or severity of an exaggerated, sustained immunological/systemic response?
- Are there any material-related factors that may predict, increase, or decrease the likelihood and/or severity of an exaggerated, sustained immunological/systemic response?
- What critical information gaps exist and what research is needed to better understand this issue?
Surgical mesh results in high infection and hospitalisation rates
The report states that “data pointed to infection in 40% of event reports associated with PP mesh. There were five deaths, and when patient harm was reported, 44% required intervention or hospitalisation.” This is a very high incidence of infection that warrants further research.
There is low quality of evidence around pain, mesh migration and hernia mesh
The report found moderate to low quality of evidence about inflammation, mesh migration and pain related to general surgical mesh and transvaginal prolapse mesh. They found no evidence at all relating local responses for diaphragmatic hernia meshes and male SUI mesh. The report calls for higher quality of evidence on local responses to PP mesh.
There are big research gaps around systemic responses
Worryingly, questions 3 and 4 posed by the FDA—which consider factors that contribute to a immunological or systemic response—could not be answered. The ECRI concluded that “none of the studies provided useful information regarding material-related factors that may affect a sustained immunological/systemic response.” This is because there were few studies that reported any data related to systemic reactions, and where they did, the quality of evidence was low. The report calls for “higher quality of evidence around systemic responses to PP mesh as there is currently very low to low quality of evidence.” This applies to both PP as a material and specific PP mesh devices.
Some mesh causes more complications than others
The report states that “evidence suggested that lightweight PP mesh was less likely than heavier weight PP mesh to cause pain or foreign body sensation.” Mesh-specific research is needed to identify which patients are most at risk of complications from individual mesh products. Although mesh is no longer being used in the UK to treat female SUI and prolapse, it is still being used in a wide range of other surgical procedures in the UK, and there are no restrictions on its use in many countries. The report highlights that, “there were no studies on diaphragmatic hernia mesh and male SUI mesh that met the inclusion criteria, either in terms of local or systemic responses,” and calls for specific studies on these procedures and devices.
What’s next for surgical mesh research?
The huge gaps in research evidence about PP mesh that the report highlights have serious implications. As there is little ‘evidence’ of harm, it allows the healthcare system to ignore the concerns of patients suffering with debilitating complications.
This is particularly the case with systemic reactions to mesh—until we have some clear, peer-reviewed evidence around the link between autoimmune conditions, the pattern of patients having their symptoms dismissed will continue. We need health services and funders to take this knowledge gap seriously and invest in understanding the true extent of harm caused by surgical mesh.
Mesh News Desk - Strattice hernia mesh trial preparation underway (17 October 2022)
1 Kent C. Transvaginal mesh timeline: the gynaecological scandal that rocked the world. Medical Device Network, 9 January 2020
2 Baylón K, Rodríguez-Camarillo P, Elías-Zúñiga A et al. Past, Present and Future of Surgical Meshes: A Review. Membranes. 7 September 2017
3 Lucas S. Medical Device Material Performance Study: Polypropylene Safety Profile. Emergency Care Research Institute, 2020