Comparison of reporting phase I trial results in ClinicalTrials.gov and matched publications

Background Data on completeness of reporting of phase I cancer clinical trials in publications are lacking. Methods The ClinicalTrials.gov database was searched for completed adult phase I cancer trials with reported results. PubMed was searched for matching primary publications published prior to November 1, 2016. Reporting in primary publications was compared with the ClinicalTrials.gov database using a 28-point score (2=complete; 1=partial; 0=no reporting) for 14 items related to study design, outcome measures and safety profile. Inconsistencies between primary publications and ClinicalTrials.gov were recorded. Linear regression was used to identify factors associated with incomplete reporting. Results After a review of 583 trials in ClinicalTrials.gov , 163 matching primary publications were identified. Publications reported outcomes that did not appear in ClinicalTrials.gov in 25% of trials. Outcomes were upgraded, downgraded or omitted in publications in 47% of trials. The overall median reporting score was 23/28 (interquartile range 21-25). Incompletely reported items in >25% publications were: inclusion criteria (29%), primary outcome definition (26%), secondary outcome definitions (53%), adverse events (71%), serious adverse events (80%) and dates of study start and database lock (91%). Higher reporting scores were associated with phase I (vs phase I/II) trials (p<0.001), multicenter trials (p<0.001) and publication in journals with lower impact factor (p=0.004). Conclusions Reported results in primary publications for early phase cancer trials are frequently inconsistent or incomplete compared with ClinicalTrials.gov entries. ClinicalTrials.gov may provide more comprehensive data from new cancer drug trials.