Squaric acid dibutyl ester (
SADBE) is a commonly used treatment for
verruca vulgaris of childhood. Few studies, however, have examined the role of
SADBE in combination with other topical
therapies for
warts. We sought to determine if
trichloroacetic acid 50% (TCA) and/or
cantharidin 0.7% improve therapeutic response to
SADBE. A retrospective chart review of 74 patients who were treated for
warts at a pediatric dermatology practice in 2010 was performed. Cox regression analysis was used to identify determinants of 100% response to
SADBE and found that number of
warts was most important (P=0.002).
Trichloroacetic acid +
SADBE resulted in 100% clearance of
warts in all subjects with the shortest time-to-clearance (hazard ratio [HR]: 2.45, 95% confidence interval [CI]: 1.14-5.25, P=0.02). In contrast, addition of
cantharidin did not improve response to
SADBE (HR: 1.13, 95% CI: 0.60-2.13, P=0.59) or TCA +
SADBE (HR: 1.16, 95% CI: 0.65-2.07, P=0.61). These results suggest that combination treatment with TCA 50% and
SADBE significantly improves the consistency and speed of
SADBE-induced clearance of
warts.