Cryotherapy with liquid nitrogen to remove common warts may be more effective than salicylic acid or a wait-and-see approach, according to the results of a randomized controlled trial reported online September 13 in the Canadian Medical Association Journal.

“Cryotherapy is widely used for the treatment of cutaneous warts in primary care,” write Sjoerd C. Bruggink, MD, from Leiden University Medical Center in Leiden, the Netherlands, and colleagues. “However, evidence favours salicylic acid application. We compared the effectiveness of these treatments as well as a wait-and-see approach.”

Between May 1, 2006, and January 26, 2007, a total of 250 consecutive, eligible patients with new cutaneous warts were recruited from 30 primary care practices in the Netherlands and were randomly assigned to 1 of 3 groups: cryotherapy with liquid nitrogen every 2 weeks, daily self-application of salicylic acid, or a wait-and-see approach. Of the 250 participants, 122 (49%) were stratified into the common wart group and 128 (51%) into the plantar wart group.

The proportion of participants with cure of all warts at 13 weeks was the main study endpoint, and analysis was by intent-to-treat. Treatment adherence, adverse effects, and satisfaction with treatment were secondary endpoints. At 4, 13, and 26 weeks, research nurses evaluated outcomes during home visits.

Age range of the participants was 4 to 79 years. At 13 weeks, 10 patients (4%) were lost to follow-up, and 240 were included in the analysis. In the cryotherapy group, cure rate was 39% (95% confidence interval [CI], 29% – 51%) vs 24% (95% CI, 16% – 35%) in the salicylic acid group and 16% (95% CI, 9.5% – 25%) in the wait-and-see group.

Because the effectiveness of treatments differed between the common wart group and the plantar wart group (P for interaction = .007), the study authors reported outcomes for all patients as well as by location of warts.

For participants with common warts (n = 116), these differences in efficacy were most pronounced. Cure rates were 49% with cryotherapy (95% CI, 34% – 64%), 15% with salicylic acid (95% CI, 7% – 30%), and 8% with the wait-and-see approach. The different treatments were not associated with significant differences in cure rates among participants with plantar warts (n = 124).

“For common warts, cryotherapy was the most effective therapy in primary care,” the study authors write. “For plantar warts, we found no clinically relevant difference in effectiveness between cryotherapy, topical application of salicylic acid or a wait-and-see approach after 13 weeks.”

Limitations of this study include self-application of salicylic acid and lack of blinding of participants, family practices, and research nurses.

“Although earlier evidence favoured salicylic acid application above cryotherapy, the present randomized controlled trial is the first that provides evidence to support the use of cryotherapy above salicylic acid, however, for common warts only,” the study authors conclude.