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

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 Patients wart-free at 8 weeks were asked to re-attend at 12 weeks; those with persistent warts at 8 weeks were withdrawn from the study.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 less than 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 less than 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.