Drug and device trial studies that are sponsored by the pharmaceutical industry are more likely to reveal statistical results and conclusions that favour a sponsor's product, a new Cochrane Library review has found.

From the design of a study, to the framing of questions and selective reporting of favourable results, the review outlined some of the most common ways industry sponsors can influence the outcome of a study.

"We found that drug industry-sponsored studies were about 30 per cent more likely to have results and conclusions that favoured the sponsor," said senior author Lisa Bero of the Charles Perkins Centre, University of Sydney.

"Currently, we have no validated way to detect or evaluate these subtle but systematic biases."