Harms were rarely specified or reported in public health randomized trials: a meta-epidemiological study

To characterize harms specification, harms reporting, concordance between specified and reported harms, transparency about harms reporting criteria, and equity-related harms considerations in randomized controlled trials (RCTs) of public health interventions.

We conducted a meta-epidemiological study of 100 RCTs of public health interventions whose primary full-text reports were published in 2023 and indexed in PubMed. Using the publication and publicly linked documents (registrations, protocols, and supplements), we assessed harms specification, harms reporting, concordance, transparency of reporting criteria, and whether reported harms were grouped by PROGRESS-Plus equity-related factors.

Only 25% (25/100) of trials specified at least one harm, and 23% (23/100) reported any harms, whereas 72% (72/100) neither specified nor reported harms. Among 28 trials that either specified or reported harms, 12 (43%) reported all specified harms, 8 (29%) reported only a subset, and 8 (29%) showed other discordance. No trial specified harms reporting criteria, and none reported harms using identifiable criteria. Trials with a registry listing and those with an identified protocol had higher odds of harms specification compared with trials without a registry or protocol (odds ratio [OR] = 4.7 [95% CI: 1.5, 14.3] and OR = 3.9 [1.5, 10.1], respectively); trials testing pharmacological interventions also showed higher odds of specification compared with other intervention types (OR = 9.8 [1.9, 49.9]). Similarly, harms reporting was higher in trials with a registry or protocol (OR = 4.0 [1.3, 12.4] and OR = 3.8 [1.4, 10.0], respectively). Although 89% of trial reports considered at least one equity-related factor among participant characteristics, none reported harms stratified by these factors. Compared with a parallel biomedical sample, public health RCTs specified and reported harms far less often.

Most public health RCTs in this sample did not publicly specify or report harms. Prespecifying how harms will be assessed and fully reporting the findings would better support decisions about adopting, modifying, or expanding public health programs. Because the sample included 100 public health RCTs and harms-related outcomes were sparse, subgroup findings should be interpreted as exploratory.

Randomized trials of public health interventions are often used to guide decisions about programs, policies, and preventive strategies. These trials should also help identify possible harms, including unintended or inequitable consequences. We included 100 randomized trials published in 2023 that evaluated public health interventions. Most neither clearly stated which harms they planned to measure nor reported harms results. Trials with a registry listing or study protocol were more likely to specify and report harms, but no trial explained the criteria used to decide which harms were reported and no trial reported harms by equity-related participant characteristics. Clearer planning and reporting would make public health trials more useful when interventions are reviewed, adapted, implemented, or scaled.