Interferon for the treatment of genital warts: a systematic review

BACKGROUND Interferon has been widely used in the treatment of genital warts for its immunomodulatory, antiproliferative and antiviral properties. Currently, no evidence that interferon improves the complete response rate or reduces the recurrence rate of genital warts has been generally provided. The aim of this review is to assess, from randomized control trials (RCTs), the efficacy and safety of interferon in curing genital warts. METHODS We searched Cochrane Sexually Transmitted Diseases Group's Trials Register (January, 2009), Cochrane Central Register of Controlled Trials (2009, issue 1), PubMed (1950-2009), EMBASE (1974-2009), Chinese Biomedical Literature Database (CBM) (1975-2009), China National Knowledge Infrastructure (CNKI) (1979-2009), VIP database (1989-2009), as well as reference lists of relevant studies. Two reviewers independently screened searched studies, extracted data and evaluated their methodological qualities. RevMan 4.2.8 software was used for meta-analysis RESULTS 12 RCTs involving 1445 people were included. Among them, 7 studies demonstrated the complete response rate of locally-used interferon as compared to placebo for treating genital warts. Based on meta-analysis, the rate of Complete response of the two interventions differed significantly (locally-used interferon:44.4%; placebo:16.1%). The difference between the two groups had statistical significance (RR 2.68, 95% CI 1.79 to 4.02, P < 0.00001). 5 studies demonstrated the complete response rate of systemically-used interferon as compared to placebo for treating genital warts. Based on meta-analysis, the rate of Complete response of the two interventions had no perceivable discrepancy (systemically-used interferon:27.4%; placebo:26.4%). The difference between the two groups had no statistical significance (RR1.25, 95% CI 0.80 to 1.95, P > 0.05). 7 studies demonstrated the recurrence rate of interferon as compared to placebo for treating genital warts. Based on meta-analysis, the recurrence rate of the two interventions had no perceivable discrepancy(interferon 21.1%; placebo: 34.2%). The difference between the two groups had no statistical significance (RR0.56, 95% CI 0.27 to 1.18, P > 0.05). However, subgroup analysis showed that HPV-infected patients with locally administered interferon were less likely than those given placebo to relapse, but that no significant difference in relapse rates was observed between systemic and placebo. The reported adverse events of interferon were mostly mild and transient, which could be well tolerated. CONCLUSION Interferon tends to be a fairly well-tolerated form of therapy. According to different routes of administration, locally-used interferon appears to be much more effective than both systemically-used interferon and placebo in either improving the complete response rate or reducing the recurrence rate for the treatment of genital warts.