Background: Cryotherapy is a standard treatment for viral warts. Although textbooks recommend treating until there is a halo of ice around the wart (traditional freeze), many authors advocate more aggressive cryotherapy. There are no previously published studies assessing the efficacy of longer freezing times.
Objectives: To compare the efficacy of the traditional freeze and a sustained 10-s freeze in the treatment of common viral warts with liquid nitrogen.
Methods: Patients attending a dedicated wart clinic were randomized to receive either a traditional freeze or a 10-s sustained freeze with liquid nitrogen delivered by a spray gun. Two hundred patients were recruited, 100 in each group.
Results: After five treatments, 49 patients in the 10-s freeze group were clear of warts (64% of non-defaulters) as compared with 31 (39%) of those in the traditional freeze group (chi2 = 6.7; P = 0.009). Seventy-four patients in the 10-s freeze group as compared with 59 in the traditional freeze group had either improved or cleared after five treatments (chi2 = 5.0; P = 0.02). Morbidity was significantly greater in the 10-s freeze group. Sixty-four patients suffered pain or blistering as compared with 44 in the traditional freeze group (chi2 = 10.8; P = 0.0045). Five patients were withdrawn from the 10-s freeze group because of pain as compared with one patient in the traditional freeze group.
Conclusions: A 10-s sustained freeze is more effective in the cryotherapy of viral warts but carries a significantly greater morbidity in terms of pain and blistering.