Open access policies of leading medical journals: a cross-sectional study.

Most leading medical journals do not offer to authors reporting commercially funded research an open access licence that allows unrestricted sharing and adaptation of the published material. The journals' policies are therefore not aligned with open access declarations and guidelines. Commercial research funders lag behind academical funders in the development of mandatory open access policies, and it is time for them to work with publishers to advance the dissemination of the research they fund.