About 12 of the world's most prominent medical journals are issuing a joint editorial this week stating that they will reject any scientific studies that do not come with an assurance that the sponsor -- whether a drug company or other organization -- gave researchers complete access to the data and freedom to report the findings. The unprecedented stand by journals based in eight countries is a response to what editors say is excessive control by drug companies over how the results of studies they sponsor are analyzed, interpreted and reported. "This is a very widely prevalent problem which . . . has profound public health implications," said Richard Horton, editor of the British journal the Lancet, one of the participating journals. In some cases, patients have died because published studies overstated drugs' benefits or minimized their risks, Horton said.