Evidence of improved reporting of swine vaccination trials in the post-REFLECT statement publication period.

The objective of this study was to describe the proportion of reporting the method used to assign study units to treatment groups; the proportion of reporting a random allocation approach; the proportion of reporting 18 REFLECT items; and the proportion of having a low risk-of-bias assessment in swine vaccination trial studies published after the REFLECT statement, compared to studies published before. The study population was 61 studies which evaluated vaccines targeted at pathogens affecting swine health or pork safety. Two reviewers assessed the reporting of 18/22 REFLECT items and five risk-of-bias domains. Authors reported the method used to allocate experimental units in 33/42 (79%) and 14/19 (74%) studies published prior and following REFLECT, respectively. There has been a substantial shift in the reporting of allocation approaches. Before 2011, only 2 of 25 (8%) studies that reported using random allocation, provided supporting evidence, and this increased in studies published between 2011-2017 to 4 of 6 (66%). Before 2011, 8 of 33 (24%) studies reported using systematic allocation, and between 2011 and 2017 6 of 14 (43%) studies reported using systematic allocation. There has also been an increase in the prevalence of reporting for 14 of the 18 REFLECT items. There is an increase in the number of studies reporting evidence to support true randomization to group, and data that suggests few baseline imbalances. Data from this study suggests reporting of swine vaccination trials is improving, which may be due to researchers having more access to better quality information.