Published trials of TACE for HCC are often not registered and subject to outcome reporting bias.

BACKGROUND & AIMS: In 2005, the registration of all randomised controlled trials (RCTs) before enrolment of participants became a condition for publication by the International Committee of Medical Journal Editors to increase transparency in trial reporting. Among RCTs on transarterial chemoembolisation (TACE) for the treatment of hepatocellular carcinoma (HCC) published after 2007, we assess the proportion that were registered and compare registered primary outcomes (PO) with those reported in publications to determine whether primary outcome reporting bias favoured significant outcomes.

METHODS

We searched MEDLINE and EMBASE for reports of RCTs evaluating TACE for HCC treatment between 1 September 2007 and 31 March 2018. Registration and publication information for each included RCT was compared using a standardised data extraction form.

RESULTS

Thirteen out of 53 (25%) included RCTs were correctly registered ( before the starting date of the RCT), 14 (26%) were registered after the RCT starting date, and 26 (49%) were not registered. Six out of 14 of the retrospectively registered RCTs (43%) were registered after their completion date. The PO was clearly reported in the published article of all registered RCTs, whereas the report was not clear in 8/26 (31%) of the non-registered RCTs ( = 0.01). Among registered RCTs, 8/27 (30%) had major discrepancies between registered and published PO. The influence of these discrepancies could be assessed in 6 of them and was shown to statistically favour significant results in 2.

CONCLUSIONS

Registration and outcome reporting in RCTs on TACE for HCC are often inadequate. Registration should be reinforced because it is a key to transparency.

LAY SUMMARY

Trial registration is fundamental to our understanding and interpretation of results, as it provides information on all relevant clinical trials (to place the results in a broader context), and on the details of their associated protocols (to ensure that the scientific plan is followed). Once a randomised controlled trial (RCT) is completed, the trial results are usually publicly shared via scientific articles that are expected to thoroughly and objectively report them. This study shows that half of the RCTs evaluating transarterial chemoembolisation for hepatocellular carcinoma were not registered, and identified major discrepancies between registered and published primary outcome favouring significant results.