There are certain things that go under the rubric “complementary medicine” that also boast they represent the Wisdom of the Ages — old therapies for currently difficult conditions that turn out to be just as good as our current therapies. Or just as bad. This week the British Medical Journal has a case in point: the use of maggots for wound healing (Dumville et al., “Larval therapy for leg ulcers (VenUS II): randomised controlled trial,” BMJ 2009;338:b773 [doi:10.1136/bmj.b773]).
The wounds in this case were the notoriously difficult to treat leg ulcers that develop as a result of impaired circulation in the elderly. There were 267 patients from various health care settings in the UK with at least 25% of the ulcer covered with slough or necrotic tissue. Nasty wounds. Maggots were either applied loose or bagged or a standard treatment with a hydrogel was used. Treatments were assigned randomly. The time to healing of the largest ulcer was the primary outcome measure, but other things were also considered such as time to debridement (removal of dead tissue), measures of health related quality of life, bacterial load, presence of MRSA and ulcer related pain (as estimated along a linear scale by the patient). There were some significant differences. Maggots got rid of the dead material faster (time to debridement) but for either maggot group patients reported more ulcer pain. Wound healing, MRSA and other measures were not sufficiently different for the numbers to allow a sound judgment that chance was not involved, although the hydrogel had eradicated 75% of MRSA by the end of the debridement phase versus only 50% for the maggots (this is of only 6.&5 of patients who had MRSA at the start).
One thing that observations over the years indicated about maggots seems to be true. They work faster at removing dead an devitalized tissue than the usual treatments. This plausibly suggested that their use would speed healing, remove bacterial load and perhaps even eliminate methicillin resistant Staph aureus (MRSA). While plausible, it turned out not to be the case. Moreover there was more pain associated with the ulcers than with conventional treatment. Prior to this study the only randomized trial of larval therapy (the nice term for maggots) used only speed of debridement as outcome. When further outcome measures are used, particularly time to actual healing of the wound and pain, there is no demonstrable advantage to the method.
What about cost? In an accompanying paper the authors try to estimate the difference:
The time horizon was 12 months and costs were estimated from the UK National Health Service perspective. Cost effectiveness outcomes are expressed in terms of incremental costs per ulcer-free day (cost effectiveness analysis) and incremental costs per quality adjusted life years (cost utility analysis).
Results The larvae arms were pooled for the main analysis. Treatment with larval therapy cost, on average, £96.70 (109.61; $140.57) more per participant per year (95% confidence interval -£491.9 to £685.8) than treatment with hydrogel. Participants treated with larval therapy healed, on average, 2.42 days before those in the hydrogel arm (95% confidence interval -0.95 to 31.91 days) and had a slightly better health related quality of life, as the annual difference in QALYs was 0.011 (95% confidence interval -0.067 to 0.071). However, none of these differences was statistically significant. The incremental cost effectiveness ratio for the base case analysis was estimated at £8826 per QALY gained and £40 per ulcer-free day. Considerable uncertainty surrounds the outcome estimates.
One of the things you can see — and the authors are straightforward about it — is that the estimates they make for cost and outcome aren’t especially precise despite the fairly large patient population. This is probably a reflection of the wide variability in the condition itself. All ulcers are not the same. So on the basis of these data you might or might not want to make a policy decision about what you will pay for. What this tells you about this particular kind of ancient form of therapy probably depends upon your predisposition about “complementary medicine.” The evidence here doesn’t establish a clear superiority for larval therapy, although it certainly shows it at least the equal of conventional therapy. But it costs more and the patient may not be as comfortable during the course of therapy.
Trade-offs. As much as we try to be precise and quantitative in medicine, it is like everything else in life — a balancing act.