Mary Madden: Should we assume medical devices work until proven otherwise?

Low standards of evidence for medical device regulation in Europe have led to clinical concerns about the potential dangers posed by the highest risk (class III) devices, especially implantable devices [1, 2]. In the wake of hip and breast implant scandals [3, 4] and in the midst of growing concerns about the widespread acceptance of the inferior vena cava filter without any evidence of efficacy [5], the MHRA (Medicines and Healthcare products Regulatory Agency) have just published an analysis of responses to their public consultation on draft new European legislation on medical devices [6]. Concerns about patient safety are in the balance against concerns about market access, because from the medical device technology industry point of view, existing quick-to-market European regulations encourage innovation through speedier regulatory approval and faster revenues [7, 8].  

A wound care research colleague and I sent a response to the MHRA’s consultation. Given time constraints we focused on improving clinical evaluation of medical devices. Where devices are being used to bring about a specific medical outcome it seems reasonable that in terms of “performance,” it is efficacy or effectiveness data that are important when making treatment decisions. In this case health professionals would ideally be guided by findings from robust RCTs and subsequent systematic review and evidence synthesis. Ideally, all devices with purported intended clinical effects should be appropriately evaluated for health and cost effectiveness. If such evaluation continues not to be a requirement for medical devices then we suggested that this should be transparent and patients and clinicians given clear information on the evidence that is (not) available. Especially, where claims for clinical effectiveness are being made in marketing literature.  Information presented could include an assessment of the evidence level as used in clinical guidelines.

We were no doubt among the “minority of respondents [who] called for more stringent requirements, similar to those placed on clinical trials for medicines.” MHRA noted, “on the other hand, a few respondents expressed concern that this approach would place disproportionate costs on manufacturers of low risk devices.” (Annex A lists the 116 organisations and individuals that responded: 40 industry, 38 individuals, 27 healthcare professionals and institutions, and 11 others.) This is an interesting presentation of an argument of evidence vs. cost without attention to health outcome. The MHRA say:

“We think that requiring pharmaceutical-style clinical trials for medical devices would be disproportionate. There is a limit to what extent devices can be assessed pre-market. Unlike medicines, it is not feasible to accurately predict the likelihood or time to failure for new medical devices via pre-market studies. In practice, such studies of sufficient size and diversity are either impractical or so onerous that they would block the product’s development process. However we strongly support requiring manufacturers to undertake rigorous clinical evaluations that are fully scrutinised by a notified body and subject to more transparency. For example, the proposed regulations place more requirements on notified bodies to have appropriate clinical expertise in place to be able to assess clinical evaluations. In principle we consider that the manufacturer’s clinical evaluation should be commensurate with the risk associated with the innovation or change.”

We are left no wiser about what is meant by “clinical evaluations,” but it sounds as if it is definitely not “pharma-style” clinical trials (by which I think they mean RCTs). We said that notified bodies need to have appropriate research expertise rather than only clinical expertise to assess clinical evaluations. There is no clear response to this. There seems to be an assumption that devices work until proven otherwise and that they are predominantly low risk. From a wound care point of view this assessment of risk in relation to classification requires more transparency. For example, a non-implantable/invasive, “benign” device like a support surface, such as a mattress to prevent pressure ulcers, may pose a significant risk to its user if it does not effectively perform the preventative medical function claimed for it.

Devices, including dressings and support surfaces for the prevention and treatment of pressure ulcers are widely used in wound care in the absence of robust clinical and cost effectiveness data.  Whilst mostly regarded as low risk in terms of causing unforeseen events, these devices are costly for health services due to volume of use as well as the increasing “technology” being incorporated into their design e.g. the introduction of silver into wound dressings now widely used in the UK with serious cost implications. The publicly funded VULCAN 2009 trial found no evidence of healing efficacy in silver dressings in venous leg ulcers [9]. “On the other hand” industry reports attribute this to a flawed trial design and claim a, “wealth of evidence and publications to support the use of … silver dressings for the treatment of chronic wounds” [10]. NHS money spent on ineffective treatments is money that cannot be spent on things that work. Wound care and management is a £1.4 billion part of the medical technology industry [11]; there is little incentive for manufacturers of devices to embark on trials that will challenge their products’ market share [5, 12].

Negative pressure wound therapy (NPWT), also known as Topical Negative Pressure (TNP) or vacuum assisted closure (VAC) is another relatively recent wound management innovation involving the application of suction to a wound using a vacuum pump. It is claimed that NPWT can speed wound closure by removing excess fluid, increasing tissue perfusion, removing bacteria and exerting a mechanical force [13], however there is lack of evidence to support it [14,15, 16]. Carlson has expressed concerns that using this Class IIb device for the management of an open abdominal wound may promote fistulae and that none of the promotional literature documents this as an adverse event [17].  A subsequent NICE audit finds that NPWT in patients with an open abdomen is not associated with an increase in mortality or intestinal fistulation, but may leave patients with abdominal wall defects that require further treatment [18]. It seems important to ask whether the benefits of immediate access to such technologies provided by an easier route to market exceed the value of the evidence which may be lost for future patients [19].

Wound care and management is an area riddled with doubt and uncertainty [20]. Lack of evidence of effectiveness is not the same as evidence of ineffectiveness, but uncertainty is exploitable. Much has been written about the ways that vested interests of industry can influence approaches to scientific uncertainty [21, 22, 23]. Evidencing effectiveness of medical devices that claim a health outcome is important in order for clinicians, patients, and the wider public to be able to decide for example, whether the “low risk” technologies used in the treatment of people with chronic wounds are worth buying.

Mary Madden has a background in community work and sociology and is a research fellow in the Department of Health Sciences at the University of York.

1. Cohen D, Billingsley M.  Europeans are left to their own devices. BMJ 2011; 342:d2748.
2. FDA Unsafe and Ineffective Devices Approved in the EU that were not approved in the US. US Department of Health & Human Services. May 2012.
3. Cohen D. Faulty hip implant shows up failings of EU regulation BMJ 2012;345:e7163.
4. Heneghan C. The saga of Poly Implant Prosthèse breast implants BMJ 2012;344:e306.
5.  Prasad V, Rho J, Cifu A. The Inferior Vena Cava Filter: How Could a Medical Device Be So Well Accepted Without Any Evidence of Efficacy? JAMA Intern Med 2013;173(7):493-495.
6.  MHRA. Response to public consultation 2013.
7. Bylander J. Eucomed Q&A: where do EU regs get it right? An emphasis on innovation. The Gray Sheet 2011;37(Mar 14):1.
8. PricewaterhouseCoopers. Medical technology innovation scorecard 2011.
9.  Michaels JA, Campbell B, King B, Palfreyman SJ, Shackley P, Stevenson M. Randomized controlled trial and cost-effectiveness analysis of silver-donating antimicrobial dressings for venous leg ulcers (VULCAN trial). British Journal of Surgery 2009: 96(10):1147-56.
10. Lindsay S. Silver White Paper: Everything you ever wanted to know about the use of silver in wound therapy. Systagenix 2011:22.
11. BIS (2012) Strength and Opportunity 2012: The landscape of the medical technology, medical biotechnology, industrial biotechnology and pharmaceutical sectors in the UK. p. 13.
12. Madden. M. Alienating evidence based medicine vs. innovative medical device marketing: A report on the evidence debate at a Wounds conference. Soc Sci Med Volume 74, Issue 12, June 2012, Pages 2046–2052.
13. Banwell PE, Musgrave M. Topical negative pressure therapy: mechanisms and indications. International Wound Journal, 1, 2004:95-106.
14. Fisher A, Brady B. 2003. Vacuum assisted closure therapy. Canadian Coordinating Centre for Health Technology Assessment: Issues in Emerging Health Technologies, 44.
15. Pham CT, Middleton PF, Maddern GJ. The safety and efficacy of topical negative pressure in non-healing wounds: a systematic review. Journal of Wound Care 15, 2006: 240-250.
16. Webster J, Scuffham P, Sherriff KL, Stankiewicz M, Chaboyer WP. Negative pressure wound therapy for skin grafts and surgical wounds healing by primary intention. Cochrane Database Syst Rev. 2012 Apr 18;4:CD009261. doi: 10.1002/14651858.CD009261.pub2.
17. Carlson GL. Management of the open abdominal wound – results of audit. Oral paper given at Wounds UK conference, Harrogate 17/11/2010.
18. Carlson GL, Patrick H, Amin AI, McPherson G, Maclennan G, Afolabi E, Mowatt G, Campbell B. Management of the Open Abdomen: A National Study of Clinical Outcome and Safety of Negative Pressure Wound Therapy. Ann Surg. 2013 Mar 8 [Epub ahead of print]
19. Griffin SC, Claxton KP, Palmer SJ, Sculpher MJ. Dangerous omissions: the consequences of ignoring decision uncertainty. Health Econ. 2011 Feb;20(2):212-24.
20. Madden M. My turn and my right. Lancet 2012 Dec 8;380(9858):1992-3; author reply 1993. doi: 10.1016/S0140-6736(12)62154-0. Comment on Not my turn. [Lancet. 2012]
21. Angell, M. The Truth About the Drug Companies: How they deceive us and what to do about it. New York: Random House. 2005.
22. Michaels D. Doubt Is Their Product: How Industry’s Assault on Science Threatens Your Health. New York: Oxford University Press 2008.
23. Goldacre B. Bad Pharma: How drug companies mislead doctors and harm patients. London: Fourth Estate 2012.