35% of Healthcare Reviews Fail to Report Side Effects

In more than a third of published health study reviews, the potential side effects of health interventions were not fully reported, according to investigators at the University of York.

A health intervention that includes negative outcomes refers to either a drug reaction or an effect of a procedure, like surgery. Since they are rare and long-term, harmful side effects can be challenging to analyze as an outcome of a health intervention.

However, investigators argued that reviews of healthcare interventions should include harmful side effects since they are essential to fully educate medical practice, health policies, and patients. Consequently, a team of investigators from the University of York sought to assess the risk for adverse events reporting bias in systematic reviews of health care interventions registered to PROSPERO.

In 187 systematic reviews published between 2017 and 2018, investigators analyzed the reporting of adverse events in their study. In health research, systematic reviews strive to summarize the results of controlled healthcare interventions and provide evidence of the effectiveness of a healthcare intervention. Overall, the study served as a retrospective cohort study.

Following a screening, systematic review protocols in PROSPERO were only included if they focused on a health care intervention and documented an adverse event as either a primary or secondary outcome.

In order to determine the completeness of reporting for the adverse event outcomes, the included systematic reviews were analyzed. Between both protocol and review, any discrepancies were recorded.

Among the results, the study showed that side effects of the medical intervention under review were not fully reported by 35% of reviewers.

Only 524 (38%) of 1376 protocols for systematic reviews sifted recorded adverse event outcomes. In 2017 and 2018, 186 protocols were published. Of those 186, 146 were included in the analysis.

Of all 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.

“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,” Su Golder, PhD, from the University of York's Department of Health Sciences said in a statement.

From their results, investigators concluded that 35% of PROSPERO-registered systematic reviews had discrepant outcome reporting between the protocol and publication while 62% of reviews did not mention adverse events in their protocol. A need for the encouraged use of harms reporting guidelines and further research into adverse events reporting bias are suggested by the study’s findings.

"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,” Golder added.

Although it was not clear why review authors might be missing or only partially reporting adverse events, the reasons may vary. In addition to finding the reasons may be wide-ranging, investigators found noted that the wide range could be due to issues like differences how the original studies had defined or recorded adverse events or simply not having the available space to include details in a word-count sensitive review.

"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,” Golder concluded.

The study, titled, “More than one-third of systematic reviews did not fully report the adverse events outcome,” was published online in Journal of Clinical Epidemiology.