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.