Researchers from the Nordic Cochrane Centre in Denmark said that the profits of drug companies were being prioritised over patient welfare by holding back the information.
The team has called for full access to published and unpublished full trial reports in a bid to allow the scientific community to make an independent assessment of what treatments have to offer.
Peter Gotzsche and Dr Anders Jorgensen said: “Doctors are unable to choose the best treatments because research results are being reported selectively.”
The researchers said: “There is something fundamentally wrong with our priorities in healthcare if commercial success depends on withholding data that are important for rational decision making by doctors and patients.”
The research, published by the BMJ, suggested that selective reporting can have “disastrous consequences”.
The report said: “Anti-arrhythmic drugs have probably caused the premature death of about 50,000 Americans each year in the 1980s.”
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