Abstracts presented at the American Society of Clinical Oncology conference: how completely are trials reported?

Purpose To assess how completely trials published in conference proceedings are reported and whether this has changed over time. Methods Conference abstracts published at the American Society of Clinical Oncology (ASCO) conference (1992 and 2002) were read to identify reports of randomized trials. A checklist was devised (based on CONSORT) to assess the completeness of reporting. Results Four-hundred and ninety-four abstracts reporting randomized trials were identified; 209 in 1992 and 285 in 2002. More trials included "randomized" in the title in 2002 compared to 1992 (54% versus 36%). Almost no trials stated the method of allocation concealment, 12% stated the method of blinding, 95% described eligible participants and 98% described the interventions. Ninety-five per cent reported the number of participants in each trial. The median number of participants per trial increased over time; 120 in 1992 and 209 in 2002 (P < 0.01). In 1992, 67% of trials reported the number of participants analysed, compared to only 49% in 2002 (P < 0.01), 28% reported or suggested intention to treat analysis dropping to 15% in 2002. Twenty-nine abstracts in 2002 and five in 1992 reported no results, with a promise of presentation at the meeting. Conclusions The reporting of conference abstracts for trials should be improved to further facilitate understanding of their conduct and validity.