The thin line between non-inferiority clinical trials H and type II errors^*

La delgada línea de ensayos clínicos de no inferioridad y el error tipo II

Luis Enrique Chaparro^a,**, Laura Girón-Arango^b

^a MD, Department of Anesthesia, University of Toronto, Toronto, Canada
^b MD, Anesthesiolog y Resident, Universidad CES, Medellín, Colombia

^* Please cite this article as: Chaparro LE, Giron-Arango L. La delgada línea de ensayos clínicos de no inferioridad y el error tipo II. Rev Colomb Anestesiol. 2016;44:73.
^** Corresponding author at: 12th Floor, 123 Edward Street, Toronto, Ontario M5G 1E2, Canada.
E-mail address: lechaparro@gmail.com (L.E. Chaparro).

We welcome a randomized clinical trial (RCT) evaluating the sedation¹ strategies for low-risk patients requiring spinal anesthesia.² The authors conclude that there is no difference between groups except for higher withdrawal reflex and/or pain from puncture in the group that only received midazolam. In a purely academic spirit, we would like to underscore a few ideas.

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Ideally, an RCT requires one person to administer the medication and a second one to assess the outcomes. If this is not possible, the effect of the intervention may be overestimated (around 40%).³ However, we empathize with those authors that sacrifice their own resources for the sake of science.⁴

1. The primary outcome variable - sample size calculation -should be explicit. This is a usual issue with RCT.⁵

2. When designing the essay: were the authors looking for the advantages of combination therapy versus the use of midazolam or on the contrary, were they looking for equivalence among interventions? - equivalence trials require hundreds and some times thousands of participants to avoid type II errors (assuming no difference when in fact there was a difference).⁶

3. We don't want to look heartless, but would it be unreasonable to consider a placebo group (no sedation) or background music⁷ for patients who just need a spinal injection?... sedation enhances the tolerance to the procedure but may deteriorate patient's cooperation for positioning.

Funding

Conflicts of interest

The authors have no conflicts of interest to declare.

References

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