Validity of observational evidence on putative risk and protective factors: appraisal of 3744 meta-analyses on 57 topics.
Perrine JaniaudArnav AgarwalIoanna TzoulakiEvropi TheodoratouKonstantinos K TsilidisEvangelos EvangelouJohn P A IoannidisPublished in: BMC medicine (2021)
Acknowledging that no gold-standard exists to judge whether an observational association is genuine, statistically significant results are common in observational studies, but they are rarely convincing or corroborated by randomized evidence.