MAASTRICHT, The Netherlands -- Warts (verruca vulgaris), have proved too much for duct tape, the all-purpose fixer, researchers here reported.
MAASTRICHT, The Netherlands, Nov. 6 -- Warts (verruca vulgaris), have proved too much for duct tape, the all-purpose sticky fixer, researchers here reported.
After six weeks, the warts disappeared in only 16% of school children afflicted with warts, an effect no better than placebo, reported Marcus Spigt, Ph.D., of Maastricht University here, and colleagues, in the November issue of the Archives of Pediatric and Adolescent Medicine.
The results of their randomized controlled trial of 103 children differed sharply from an earlier study of cryotherapy versus duct tape occlusion therapy. In that study the tape resolved warts after two months in 85% of the participants. However, the results have been debated because the study was small and lacked a control group, said Dr. Spigt.
In a previous review of 50 wart- therapy trials, only salicylic acid was found effective, an awkward and uncomfortable therapy, they added.
In the current study of children ages four to 12, 51 were randomized to the duct-tape intervention and 52 to placebo. The tape and placebo (a corn pad protection ring) sticker were changed once a week and worn for seven days. The transparent tape was removed from the original roll and pasted on sticker paper. If the tape came off, parents were instructed to apply a new piece.
On the evening of the seventh day, the tape was removed, the wart was soaked in warm water and rubbed gently with a pumice stone, a treatment the children found unpleasant. Fresh tape was applied on the next day. The placebo children, told they would "receive some kind of tape," also soaked and pumiced the wart. Patients were blinded to the hypothesis of the study.
The baseline size of the treated wart was comparable between the two groups. In the duct-tape group, fewer warts were located on the finger or dorsum of the hand and more warts were located at the toe or foot. The warts had existed longer in the duct-tape group than in the placebo group (34.2 versus 38.5 weeks).
After six weeks, the wart had disappeared in only eight children (16%) in the tape group and three children (6%) given placebo treatment P=.12). The difference was not statistically significant, the researchers reported.
In the duct-tape group, after six weeks, there was a diameter reduction of the treated wart of 27% (from a mean of 4.6 mm to 3.4 mm). In the placebo group, this was 9% (from 4.4 mm to 4.0 mm). When adjusted for the baseline diameter, this resulted in a statistically significant difference of 1.0 mm between the two groups (P=.02, 95% CI -1.7 to -0.1).
Duct-tape treatment did not seem to have any effect on surrounding warts, the researchers said. After six weeks, a surrounding wart had disappeared in only seven children (21%) in the duct-tape group, compared with nine children (27%) in the placebo group (P=.79).
Seven duct-tape children (15%) reported adverse effects, mainly erythema, eczema and wounds compared with none in the placebo group (P=.14).
Finally, both groups reported pain and/or bleeding caused by the pumice stone, and none of the children used other wart therapies during the study.
As for the tape itself, only 19% of the tape group judged the stickiness of the tape as good. Both groups used additional fixation material (32% vs 33%). Significantly, only one of the eight children who had complete wart resolution judged the tape as sticking well, the researchers said.
"In our view this is crucial because it makes the treatment a bothersome rather than a feasible alternative for other wart therapies, Dr. Spigt's team said. In addition, 15% of the children in the duct tape group showed adverse effects.
Finally, the researchers wrote that given that the estimated effect of placebo is 30% in 10 weeks, the overall 6% placebo effect was surprising. One explanation, they suggested, could be that in both groups, some of the children had already used other wart therapies, resulting in more resistant warts. Forty-seven percent in the duct tape group vs 62% in the placebo group had received prior wart treatment. Regression toward the mean and other variables may also have been factors, they said.
Both duct tape and placebo might do better in other studies, but it is crucial, they said, that this was not the case in this study. Therefore, they said, "We do not think that when subjected to firm investigation, the duct tape would do much better than placebo or better than other effective interventions."
In discussing further research, the investigators had the following advice. Use a very sticky tape, use a longer follow-up period to observe any effect of the tape, and above all, don't use the pumice stone. Many children found it very unpleasant, and bleeding could spread the wart virus.
As part of an evidence-based journal club feature published in the same issue, the study was reviewed by Jeanne Van Cleave, M.D., Alex R. Kemper, M.D., M.P.H., and Matthew M. Davis, M.D., of the University of Michigan. They offered a number of critical comments, and pointed out that the assumptions "regarding the spontaneous wart resolution rate and a meaningful clinical difference were so substantively different from what they actually found that they were left underpowered to assess their study hypotheses."
However, they added, several methodological limitations in the new study "lead us to question the investigators' conclusions that the effects of duct tape were not significant. Further studies that address the limitations of these extant studies are needed before such definitive conclusions can be drawn."