The Food and Drug Administration's warning last summer of the risks associated with transvaginal placement of mesh for repair of pelvic organ prolapse and stress urinary incontinence – and its overall, ongoing review of how mesh products are cleared for use–have changed the climate for ob.gyns. and patients. It has upped the ante for comprehensive patient counseling and brought to the fore the fact that pelvic floor repair is a combination of art, science, judgment, skill, training, and experience.
In July 2011, the FDA issued a “safety communication” to physicians and patients, which was based on an analysis of adverse event reports and a systematic literature review, warning that the transvaginal placement of mesh to treat pelvic organ prolapse (POP) appears to be riskier than traditional repairs without any evidence of greater effectiveness. While an earlier FDA notice issued in 2008 had said in essence that there may be a problem with transvaginal mesh, the most recent warning said there is a problem – that serious complications associated with surgical mesh used for transvaginal repair of POP are not rare.
The agency made a distinction between apical and posterior repair, and anterior repair, concluding that there is no evidence that either apical or posterior repair done with mesh provides any added benefit compared with traditional surgery without mesh.
With regard to anterior repair, the FDA concluded that mesh augmentation may provide an anatomic benefit compared with traditional nonmesh repair, although this anatomic benefit may not necessarily lead to better symptomatic results.
The FDA also reviewed all types of midurethral sling (MUS) devices used to treat stress urinary incontinence (SUI), grouping retropubic and transobturator slings as first-generation and mini-slings as second-generation devices.
Whereas these devices were deemed to be as effective as or better than traditional repairs, the FDA stated its concerns about the potential for long-term problems including mesh erosion and pelvic pain. Moreover, the agency stated the need for more data to better evaluate mini-slings for comparative efficacy and complications.
More broadly, the FDA is reevaluating how transvaginal mesh products should be regulated and brought to market. Unlike other devices that are widely used by ob.gyns., not one of the pelvic floor mesh kits for POP or midurethral slings for SUI has been evaluated by way of an independent, FDA-mandated randomized clinical trial. This is because transvaginal meshes are currently classified as class II devices and, as such, have been cleared for market by the less rigorous 510(k) notification process rather than a more rigorous premarket approval (PMA) process.
While the FDA considers the 510(k) pathway still suitable for MUS devices used to treat SUI, the agency is taking a harder look at transvaginal mesh used to repair POP and has recommended reclassification of these devices into class III. This switch would require the more onerous PMA process and allow the FDA to require clinical trials comparing procedures that involve mesh with those in which mesh is not used.
How the FDA Regulates Devices
That transvaginal mesh devices are embroiled in a broader and ongoing controversy over how best to regulate or approve medical devices is important to understand. Innovation and potential market share continue to drive a steady stream of new medical devices for gynecologic surgery.
Until 36 years ago there was no federal regulation of medical devices. The Medical Device Amendments of 1976 established three device classes, based on risk levels and the ability of postmarketing controls to manage those risks. The law then identified pathways, based largely on this classification system, for bringing devices to the market.
Class I devices are generally those for which general postmarketing controls such as good manufacturing processes and record keeping are deemed sufficient to provide reasonable assurance of safety and effectiveness. Devices in class II, which are “moderate risk,” need special controls such as performance standards and postmarketing surveillance to provide reasonable assurance of safety and effectiveness. In class III are life-sustaining or life-supporting “high-risk” devices that cannot be placed in class I or II because there is insufficient information to establish requisite assurance with postmarketing controls.
While FDA-approved randomized and controlled clinical trials are required for class III devices as part of the standard PMA process, class II devices are cleared for the market based on the substantially less rigorous 510(k) Premarket Notification Program process, which requires manufacturers to demonstrate safety and effectiveness by proving “substantial equivalence” to another device that is already cleared by the FDA based on intended use and product design.
Whereas clinical data are not required, this review of substantial equivalence requires labeling and performance data, including material safety, mechanical performance, and animal testing. Approval of the first surgical mesh for repair of POP was judged to be substantially equivalent to surgical mesh used for hernia repair.