Local treatments for cutaneous warts.

BACKGROUND

Viral warts caused by the human papilloma virus represent one of the most common diseases of the skin. Any area of skin can be affected although the hands and feet are by far the commonest sites. A very wide range of local treatments are available.

OBJECTIVES

To assess the effects of different local treatments for cutaneous, non-genital warts in healthy people.

SEARCH STRATEGY

We searched the Cochrane Controlled Trials Register (March 1999), the Skin Group trials register (March 1999), MEDLINE (1966 to August 2000), EMBASE (1980 to August 2000) and a number of other key biomedical and health economics databases. In addition the cited references of all trials identified and key review articles were searched. Pharmaceutical companies involved in local treatments for warts and experts in the field were contacted.

SELECTION CRITERIA

Randomized controlled trials of local treatments for cutaneous non-genital viral warts in immunocompetent human hosts were included.

DATA COLLECTION AND ANALYSIS

Study selection and assessment of methodological quality were carried out by two independent reviewers.

MAIN RESULTS

Forty-nine trials were identified which fulfilled the criteria for inclusion in the review. The evidence provided by these studies was generally weak because of poor methodology and reporting. In 17 trials with placebo groups that used participants as the unit of analysis the average cure rate of placebo preparations was 30% (range 0 to 73%) after an average period of 10 weeks (range 4 to 24 weeks). The best available evidence was for simple topical treatments containing salicylic acid, which are clearly better than placebo. Data pooled from six placebo-controlled trials show a cure rate of 144/191 (75%) compared with 89/185 (48%) in controls, odds ratio 3.91 (95% confidence interval 2.40 to 6.36), random effects model. Most of the bigger trials of cryotherapy studied different regimens rather than comparing cryotherapy with other treatments or placebo. Pooled data from two small trials that included cryotherapy and placebo or no treatment, showed no significant difference in cure rates. In two other trials comparing cryotherapy with salicylic acid no significant difference in efficacy was demonstrated. There was no consistent evidence for the effectiveness of intralesional bleomycin. Four studies, using warts rather than individuals as the unit of analysis, had widely varying results which could not be meaningfully pooled. There was some evidence for the efficacy of dinitrochlorobenzene, a potent contact sensitizer. Pooled data from two small studies comparing dinitrochlorobenzene with placebo showed cure rates of 32/40 (80%) and 17/40 (43%) respectively, odds ratio 5.42 (95% confidence interval 1.99 to 14.75), random effects model. Only limited evidence was found for the efficacy of topical 5-fluorouracil, intralesional interferons and photodynamic therapy. Bleomycin, dinitrochlorobenzene, 5-fluorouracil, interferons and photodynamic therapy are potentially hazardous or toxic treatments.

REVIEWER'S CONCLUSIONS: There is a considerable lack of evidence on which to base the rational use of the local treatments for common warts. The reviewed trials are highly variable in method and quality. Cure rates with placebo preparations are variable but nevertheless considerable. There is certainly evidence that simple topical treatments containing salicylic acid have a therapeutic effect. There is less evidence for the efficacy of cryotherapy and no convincing evidence that it is any more effective than simple topical treatments. Dinitrochlorobenzene appears to be effective but no more so than the safer, simpler and cheaper topical treatments containing salicylic acid. The benefits and risks of 5-fluorouracil, bleomycin, interferons and photodynamic therapy remain to be determined.