Interim publication of randomized trial results could be confusing, misleading

Researchers might be jumping the gun when publishing interim results of randomized trials, according to new information out of Dartmouth University. In roughly 20 percent of cases, results differ significantly by the time final numbers are published.

“Changes between interim and final publication matter because clinicians and the public could have been misled about whether an intervention was beneficial, harmful or ineffective,” co-lead researcher Lisa M. Schwartz, MD, MS, said in a release from Dartmouth. Since interim results are new and oftentimes promising, Schwartz and co-authors wrote in the Journal of the American Medical Association, they generate interest and attention that could be misleading if a trial’s results change.

Schwartz et al. exhausted the PubMed database in an effort to discern how characteristics of interim publications compared to final results in consistency and prominence. The authors found that of 1,267 screened publications, 613 (48 percent) reported interim results.

Of those 613 studies, though, just 28 percent followed up with a final publication. The remaining 72 percent were stopped early, either for benefit or due to harm, futility or other issues, and the majority of reports failed to specify a reason for publishing interim results at all.

“Frequent nonpublication of final results means true treatment effects often remain unknown,” the authors wrote. “Interim publication should be limited to protocol-prespecified analyses performed when enough outcomes occurred for statistical stability and to scenarios least likely to undermine trial integrity.”

Still, Schwartz and colleagues said, the majority of study results didn’t differ greatly between interim and final publications. Seventy-nine percent of abstract conclusions didn’t change; 21 percent changed significantly.

Making a habit of including the word “interim” in publication titles and justifying the reason for publishing early results within the article could help alert readers to “inherent uncertainties,” the authors wrote.

“Journals, authors and funders should commit to making final results accessible by linking interim publications to final reports whenever available,” they said.