Subcutaneous interferon alpha 2a combined with cryotherapy vs cryotherapy alone in the treatment of primary anogenital warts: A randomised observer blind placebo controlled study

Abstract

Objective - To compare patient tolerance and treatment efficacy of subcutaneous interferon (IFN) alpha 2a plus cryotherapy versus cryotherapy alone in treatment of primary anogenital (AG) warts. Design - Randomised placebo controlled observer blind study. Statistical analysis was by chi square and Mann Whitney U tests. Patients - 60 patients with newly diagnosed AG warts. Intervention - 29 and 31 patients were treated with subcutaneous IFN alpha 2a plus cryotherapy or placebo injections plus cryotherapy, respectively. Main outcome measures - Clinical presence or absence of AG warts. Patients wart-free at 8 weeks were asked to re-attend at 12 weeks; those with persistent warts at 8 weeks were withdrawn from the study. Results - At 8 weeks 60.7% (17/28 patients) of the IFN group and 67.9% (19/28 patients) of the placebo group were clinically wart-free (not significant); corresponding figures at 12 week review were 29.6% (8/27 patients) and 40% (10/25 patients) respectively (not significant). There was no difference in treatment response between males and females. Recurrence of warts at three month review, in patients cleared of warts at 8 weeks, was seen in 50% (8/16) and 37.5% (6/16) of patients in the IFN and placebo groups respectively (not significant). Multiple warts and the presence of perianal/anal canal warts, either alone or concurrent with warts on the genitalia, at first clinic attendance, were adverse prognostic indicators (p < 0.001, and p = 0.05 respectively). Cervical human papilloma virus (HPV) infection, exophytic or subclinical, was present in 58.3% and 77.2% of females in the IFN and placebo groups respectively, at trial entry. Although these lesions were not directly treated, colposcopic resolution was seen in 12.5% of affected women, in both treatment groups, by the end of the 7 week treatment period. Systemic side effects were significantly more common in the IFN than in the placebo group, 50% versus 10.7% of patients (p < 0.01). Severe influenza-like symptoms occurred, after the first three injections only, in one patient treated with IFN; all other reported side effects were mild. Conclusions - Subcutaneous IFN alpha 2a combined with cryotherapy is no more effective than cryotherapy alone in the treatment of primary AG warts. The presence of multiple warts and perianal/anal canal warts are adverse prognostic indicators.