M. Connolly et al., Cryotherapy of viral warts: a sustained 10-s freeze is more effective thanthe traditional method, BR J DERM, 145(4), 2001, pp. 554-557
Background Cryotherapy is a standard treatment for viral warts. Although te
xtbooks recommend treating until there is a halo of ice around the wart (tr
aditional freeze), many authors advocate more aggressive cryotherapy. There
are no previously published studies assessing the efficacy of longer freez
ing times.
Objectives To compare the efficacy of the traditional freeze and a sustaine
d 10-s freeze in the treatment of common viral warts with liquid nitrogen.
Methods Patients attending a dedicated wart clinic were randomized to recei
ve either a traditional freeze or a 10-s sustained freeze with liquid nitro
gen delivered by a spray gun. Two hundred patients were recruited, 100 in e
ach group.
Results After five treatments, 49 patients in the 10-s freeze group were cl
ear of warts (64% of non-defaulters) as compared with 31 (39%) of those in
the traditional freeze group (chi (2) = 6.7; P = 0.009). Seventy-four patie
nts in the 10-s freeze group as compared with 59 in the traditional freeze
group had either improved or cleared after five treatments (chi (2) = 5.0;
P = 0.02). Morbidity was significantly greater in the 10-s freeze group. Si
xty-four patients suffered pain or blistering as compared with 44 in the tr
aditional freeze group (chi (2) = 10.8; P = 0.0045). Five patients were wit
hdrawn from the 10-s freeze group because of pain as compared with one pati
ent 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.