The potential side-effects of health interventions — either a drug reaction or an effect of a procedure, such as surgery — were not fully reported in more than a third of published reviews, a University of York study of 187 sytematic reviews has shown.
Researchers argue, however, that it is still essential that harmful side-effects are included in reviews of healthcare interventions to fully inform medical practice, health policies, and patients.
The study looked at the reporting of adverse events in 187 systematic reviews published between 2017 and 2018. Systematic reviews in health research aim to summarise the results of controlled healthcare interventions and provide evidence of the effectiveness of a healthcare intervention.
Research showed that 35% of reviewers did not fully report the side-effects of the medical intervention under review. Dr Su Golder, from the University of York’s department of health sciences, said: “Despite reviewers stating in their own protocols that adverse events should be included in the review, 65% fully reported the event as intended by the protocol, 8% entirely excluded them, and the remaining 27% either partially reported or changed the adverse event outcomes.”
“Just over 60%, however, didn’t even include adverse events in their protocols, which suggests that a more proactive approach is needed to prompt reviewers to report on potential harmful side-effects in their reporting of healthcare interventions.”
Review authors write their own protocols to describe the steps they will follow when preparing their review of healthcare data. These protocols must meet a particular standard to be accepted for publication in a public database that allows researchers, patients, professionals, and policy specialists to access trusted evidence-based information.
The reasons why review authors might be missing or only partially reporting adverse events was not clear, but the researchers found that these reasons could be wide-ranging, from how the original studies had defined or recorded adverse events, to simply not having the available space to include details in a word-count sensitive review.
Golder said: “To prevent bias in reporting of these important features of clinical trials, more work is needed to understand why so many reviewers are not fully including them and perhaps more strict guidance is needed on representing them in review protocols in the first instance.”
Objectives: The aim of the study was to assess the risk for adverse events reporting bias in systematic reviews of health care interventions registered to PROSPERO.
Study Design and Setting: This study was a retrospective cohort study. Systematic review protocols in PROSPERO were screened and included if they focused on a health care intervention and listed an adverse event as either a primary or secondary outcome. The included systematic reviews were assessed to determine the completeness of reporting for the adverse event outcomes. Any discrepancies in reporting between protocol and review were recorded.
Results: Of 1,376 protocols for systematic reviews sifted, only 524 (38%) listed adverse events outcomes. One hundred eighty-six protocols were published in 2017 and 2018, of which 146 were included in our analysis. Among the included systematic reviews, 65% (95/146) fully reported the adverse event outcomes as intended by the protocol, 8% (12/146) entirely excluded the adverse event outcome, and the remaining 27% (39/146) either partially reported or changed the adverse event outcomes.
Conclusion: Sixty-two percent of reviews did not mention adverse events in their protocol, and 35% of PROSPERO-registered systematic reviews had discrepant outcome reporting between the protocol and publication. The findings suggest a need for the encouraged use of harms reporting guidelines and further research into adverse events reporting bias.
Rachael Parsons, Su Golder, Ian Watt