Liquid nitrogen cryotherapy for common warts - comparing single vs double freeze techniques

Background: Nongenital viral warts caused by the human papilloma virus represent one of the most common diseases of the skin and cytodestructive methods, such as cryotherapy, remain the primary treatment modality. However, knowledge about its efficacy and side effects is

lacking.

Aims: 1.  To compare the efficacy of liquid nitrogen cryotherapy for common warts using single vs double freeze techniques.

2. To find the value of a second freeze-thaw cycle to warts at different anatomical sites.
3. To compare the common adverse effects of cryotherapy between the two regimes.

Method: 300 patients were randomly divided into 2 groups and liquid nitrogen was advocated using the spray gun. Both groups received one freeze-thaw cycle and the second group a second cycle at each visit. The treatment was continued every 2 weeks for a maximum of 6 visits. The overall cure rate, the cure rate of warts at different sites and the side effects of treatment modalities were compared. Significancy was calculated employing the Z test.

Results: A total of 242 (80%) patients (first group - 119, second group - 123) completed the study. Thereof, 68 (57%) patients in the single freeze group as compared to 77 (63%) in the double freeze group showed overall clearance, a difference of 6% (p>0.05). The cure rate of periungual warts in the first group was 39% and it was 66% in the second group, a difference of 27% (p<0.05). Hypopigmentation was the most common side effect noted in both groups (single - 49%, double - 41 %, p>0.05) and infection was the least common (single - 2%, double - 3%, p>0.05).

Conclusion: The use of a second freeze-thaw cycle is ineffective on the overall cure rates, but separate analysis of subjects with periungual warts revealed considerable improvement. There was no significant difference in the rates of side effects between the two groups.