Why his framework matters
Evidence-based medicine (EBM) is the formal discipline of evaluating clinical evidence on its methodological quality: study design, sample size, blinding, confounding, reproducibility, peer-review. It is the framework the NHS uses to decide whether a treatment works, whether a diagnostic test is reliable, and whether a clinical claim is supportable. It is also the framework that should apply to expert evidence in criminal trials where medical claims are the basis of conviction.
Prof. Heneghan’s public commentary on the Letby case applies the EBM framework to the trial evidence directly. His conclusion is that the Crown’s expert evidence does not meet EBM standards — the methodology, the sample size, the blinding, the confounding-control are each inadequate on current EBM criteria.
Professional background
- Professor of Evidence-Based Medicine, University of Oxford.
- Director of the Oxford Centre for Evidence-Based Medicine (CEBM).
- Practising GP.
- Sustained public-engagement work on evidence-based policy across Covid-19 response, NHS screening, diagnostic-test reliability, and contested medical claims.
- BMJ, Spectator and broadsheet contributor on evidence-based policy.
The EBM framework applied to Letby
- Study design. The Crown’s expert evidence was retrospective, hypothesis-first, unblinded case review. Under EBM, this is observational and carries specific bias risks.
- Confounding control. The cluster’s confounding factors — outbreak, staffing, infrastructure, acuity mismatch — were not formally controlled in the Crown’s expert analysis.
- Reproducibility. A different expert panel applying modern EBM methodology (the Shoo Lee Panel) reaches the opposite conclusion on the same casebook. This is the form reproducibility takes in clinical-evidence evaluation: when independent methodologically-sound replication produces opposite results, the original result is not reproducible.
- Peer-review. The Crown’s expert opinions were not published in peer-reviewed form. The Panel’s framework and the Joint Insulin Report have peer-review-layer support. The peer-reviewed literature layer is against the Crown’s framing.
Why this is load-bearing
EBM is not a fringe framework. It is the canonical UK methodology for evaluating clinical evidence. The Oxford CEBM is its flagship institution. When the director of that institution publicly states that the Crown’s evidence does not meet EBM standards, that is a specific institutional judgment about the reliability of the evidence base the conviction rests on.