Warts epitomize the dilemmas of modern medicine. They are pervasive - Verruca Vulgaris is called "the common wart" for a reason. They're not life threatening, but they diminish life quality. They can be treated with the latest high tech laser weaponry - or left to their own devices, as warts not infrequently go away without treatment.
Conditions such as warts - and depression, irritable bowel syndrome, obesity, and the common cold - are tests for our health care system. Effective treatment improves people's quality of life, while ineffective treatment is a waste of scarce resources.
There are a plethora of purported wart cures: salicylic acid, or salicylate; "cryotherapy", or freezing with liquid nitrogen; incision (cutting the wart out); lasers. Alternatively, warts can be killed by covering them with duct tape for a few days.
There is relatively little evidence on the effectiveness of alternative treatments. A 2002 study found that "duct tape occlusion therapy was significantly more effective than cryotherapy [liquid nitrogen] for treatment of the common wart." A 2006 survey of the literature concluded "Cryotherapy has similar cure rates to topical salicylate.... Duct tape may be equivalent to cryotherapy.... laser therapies may also be effective for recalcitrant warts ...." A 2011 study concluded "Evidence for the absolute efficacy of cryotherapy was surprisingly lacking....one [trial] comparing duct tape with cryotherapy showed no significant difference in efficacy."*
The type of duct tape used appears to matter: silver seems to work better than clear tape. According to this useful survey, silver duct tape uses a rubber-based adhesive, while clear uses an acrylic-based one. There may be something in the rubber adhesive that triggers an immune system response, and causes the body to fight off the human papilloma virus. The type of cryotherapy matters too. Repeated aggressive cryotherapy - long cold blasts of liquid nitrogen, applied every 2 weeks - appear to work, and cryotherapy in combination with salicyclic acid is more effective than cryotherapy alone. Half-hearted cryotherapy treatments, applied at irregular intervals, are far less effective.
Given what is known how well different methods of wart control work, it is easy to measure the cost-effectiveness of different treatments, as in this study. Since duct tape costs almost nothing, it trumps all therapies in cost-effectiveness terms. Cryotherapy carried out by a doctor is one of the least cost-effective treatments - though, in my experience, one of the most widely used ones.
Why don't doctor refuse to treat patients with freezing and burning until the patients have tried duct tape therapy? Why aren't insurance companies and governments publicizing the duct tape approach?
First, no one wants to risk being wrong. The safety of duct tape has not, as far as I can tell, been proven. Imagine what might happen if Consumer Reports was to recommend treating warts at home with duct tape. What if it was then discovered that duct tape adhesive has deadly side effects? What if some readers mistook malignant growths for warts, treated those with duct tape, and then died from untreated skin cancer? The safest advice is always "go see your doctor, and follow her recommendations."
Second, no one has an interest in advocating duct tape therapy. Blasting warts with lasers is more profitable than telling people to go home and apply some duct tape. Insurance companies and governments are generally the ones who promote cost-saving public health measures, for example, seat belt legislation. However insurance companies have found out an even better way of saving money on wart treatment: don't cover it. (Ontario's health insurance plan covers plantar warts, that is, warts on the feet, but not warts other places. Presumably this is because plantar warts are harder to treat, more debilitating, and more easily transmitted). If insurance companies and governments do not pay for wart treatment, they have no reason to be concerned about its cost.
Now, if there was a way to commercialize duct tape treatment, and charge people $30 or $50 for a few small pieces of duct tape, someone would be out there advocating for it. Odds are that researchers at some pharmaceutical company somewhere are working on this right now.
Third, people seek magic in medicine. A white suited person with a steaming vial of liquid nitrogen looks like a trusted medical professional. Anything as painful as a blast of liquid nitrogen on sensitive skin must be effective, musn't it? A person who goes to the doctor and is told "go home and stick some duct tape on your feet" may feel disappointed, disillusioned, that their visit to the physician was a waste of time.
Sometimes, when others fail to act, private charities step in. Think, for example, of the Bill and Melinda Gates Foundation's work on malaria. Unfortunately verucca vulgaris has failed to attract charitable donations, research dollars and high profile advocates. It's harder to raise funds for ugly animals than for beautiful ones; chronic problems like poverty attract relatively fewer donations than dramatic events like tsunamis. Donors get excited about saving lives, or making dramatic improvements in people's existence. Consequently, private funds for wart research are lacking.
Are warts a significant problem? For the person who is avoids shaking hands, or is ashamed to go out, because of their warts, yes. Warts can be a barrier to social interaction. Moreover, because so many people experience warts, the costs of treating them can rapidly mount up. $10, $20 or more on various over-the-counter products containing too little salicylate to take on a serious wart. Multiple visits to the doctor's office for freezing and re-freezing with liquid nitrogen. As a last resort, lasers. A $100, $200 or $300 treatment applied to some fraction of the millions of warts in this country could easily add up to a total health care bill in the hundreds of millions, or even the billion dollar range. Even if those costs are paid for by people out of their own pocket, they are still costs. Spending money on useless half-hearted cryotherapy is a waste of resources, regardless of whose resources are being wasted.
In the cosmic scheme of things, warts are a small problem. But if we can't persuade medical practitioners to adopt the most cost-effective medical protocols when it comes to little things like warts, what hope do we have of promoting cost-effective treatment in big things like cancer?