Efficacy of HPV vaccines against non-cancer lesions: systematic review and meta-analysis
METHODS: A systematic review of randomized trials was conducted. The search was performed in PubMed, Embase, Cochrane Library, Scopus, LILACS, SciELO and Web of Science from their inception until August 2013 without language restriction. References of selected articles, major international scientific sessions abstracts from 2007-2013 and clinical trial registries were also reviewed. We evaluated three outcomes: AGW, and respiratory and oral papillomatosis. Tools proposed by the Cochrane Collaboration for study quality assessment were used, and the I2 statistic was used to quantify the degree of heterogeneity between studies. Random effects models were used and effects reported as relative risks (RR) and their confidence intervals (95% CI) following both intention to treat (ITT) and per protocol (PP) analyses.
RESULTS: A total of 1598 references were found and five articles accounting for six studies were included (n=27 078). We did not find studies on vaccine efficacy in respiratory or oral papillomatosis, nor about bivalent vaccine. One study was rated “high risk of bias” due to differences in loss of follow-up. One study could not be included in the meta-analysis because it combined results on infection and disease. Quadrivalent vaccine decreased the risk of AGW by 71% (RR: 0.29; 95%CI: 0.18-0.46, I2: 55.1%) in the ITT and by 92% (RR: 0.08, 95%CI: 0.03-0.21, I2: 0%) in the PP. Subgroup analyses of studies in women or with "low-risk of bias" provided similar results.
CONCLUSIONS: HPV quadrivalent vaccine is efficacious in preventing AGW. There are no available data on respiratory or oral papillomatosis.