Unreliable summary

Selective reporting

Look out for unpublished results of fair comparisons of nutrition interventions.

The results of many fair comparisons of interventions are never published, or they are published but do not contain the results of all outcomes that they planned to measure, or should have measured. This is called “selective reporting”.

Outcome results that are published are more likely to report favourable results. As a consequence, reliance on published studies alone sometimes results in the beneficial effects of nutrition interventions being overestimated and the harmful effects being underestimated.

Biased selective reporting of research is a major problem that is far from being solved. It is scientific and ethical malpractice, and wastes research resources. Selective reporting is an important reason why fair comparisons of interventions should have protocols that are registered and searchable in study registries, such as clinicaltrials.gov. This way studies can be tracked down even if they are not published.

REMEMBER: Think about whether or not the authors of systematic reviews have considered the risk of biased selective reporting of fair comparison of interventions.