This review had clear inclusion criteria for participants, interventions and study designs. Inclusion criteria for outcomes were broad, but this appeared unlikely to have affected study selection or the findings of the review. The authors searched a wide range of sources without restrictions by language or publication status. Validity was assessed using appropriate criteria. Study selection was performed by one reviewer, increasing the risk of errors or bias at this stage, but checking was used to reduce these risks during validity assessment and data extraction. Relevant details of included studies were presented in tables. Studies were pooled by meta-analysis and possible sources of bias in the analyses were investigated extensively. The authors' conclusions were in line with the evidence presented and with previous reviews in the field, and were likely to be reliable.
The authors reported that they have been involved in a review of PDE-5 inhibitors funded by Pfizer Ltd.