domingo, 6 de noviembre de 2016

Revisando el concepto de análisis por intención de tratamiento

Referencia


Author's comment: we address these issues with an emphasis on binary outcomes, and discuss how authors of randomized trials should address issues of both noncompliance and missing data.

¿Ensayo clínico con bajo tamaño de muestra?...

...enorme papel del chance: falso positivo o falso negativo. Ni práctico ni útil.

Referencia
Nagendran M, Pereira TV, Kiew G, Altman DG, Maruthappu M, Ioannidis JP, McCulloch P.  Very large treatment effects in randomised trials as an empirical marker to indicate whether subsequent trials are necessary: meta-epidemiological assessment. BMJ. 2016 Oct 27;355:i5432. doi: 10.1136/bmj.i5432.

CONCLUSIONS:
 The frequency of VLEs followed by a large trial is vanishingly small, and where they occur they do not appear to be a reliable marker for a benefit that is reproducible and directly actionable. An empirical rule using a VLE in a randomised controlled trial as a marker that further trials are unnecessary would be neither practical nor useful. Caution should be taken when interpreting small studies with very large treatment effects.

*VLE denotes "very large effect (VLE; defined as a relative risk of ≤0.2 or ≥5)".