Reviews of Screening Interventions Often Fail to Include Relevant Harms

With any given intervention comes a set of both potential desirable as well as undesirable effects, and proper consideration should be given to both in the context of clinical decision-making. However, our knowledge about potential undesirable effects (or "harms") of an intervention depends on the availability of the evidence, just as it does with the potential benefits. A recent systematic review of reviews for screening interventions suggests that the way evidence for harms is synthesized may not follow the same rigor and depth as for an intervention's potential desirable effects, limiting our ability to throughly weigh the two against one another when making clinical decisions to inform screening behaviors.

In the January 2021 issue of Journal of Clinical Epidemiology, Johanssen and colleagues systematically searched and screened 47 Cochrane reviews, making note of those that reported including potential harms as outcomes within the search strategy, even if no available evidence was ultimately found. Overdiagnosis was only included in 15% of the 39 reviews in which the Johanssen and colleagues deemed it a potentially relevant outcome; overtreatment was mentioned in 16% of eligible reviews. The inclusion of secondary harm outcomes in potentially eligible reviews ranged from 7% (incidental findings) to 91% (all-cause mortality). While psychosocial consequences was discussed as a potential outcome in a majority (64%) of eligible reviews, the data for this outcome were often not synthesized. 

Overall, reviews were less likely to meta-analyze or assess the risk of bias for evidence around harms than for benefits. Two-thirds (67%) of summary of findings tables, however, did not include any harms as outcomes; further, 42% of abstracts and 58% of plain language summaries did not mention any harms. 

The authors conclude that these findings demonstrate a need for a "broad collaboration" to develop reporting guidelines and core outcome sets that will ensure the more thorough and rigorous reporting of harms outcomes in screening studies. Through a consensus process involving a diverse set of stakeholders including clinicians, methodologists, policymakers, and medical ethicists, improved standards can be set for the reporting of all outcomes of screening interventions that are of potential relevance to patients.

Johansson M, Borys F, Peterson H, et al. 2021. Addressing the harms of screening - A review of outcomes in Cochrane reviews and suggestions for next steps. J Clin Epidemiol 129:68-73.

Manuscript available from the publisher's website here.