Only Six Participants Had Severe Baseline Anxiety in the CBD Scan Trial
The scan-anxiety trial stratified randomization by baseline anxiety severity, but only six participants were in its severe category. Stratification did not supply enough data for a reliable severe-anxiety subgroup analysis.
The strata helped organize allocation
Participants were assigned within GAD-7 categories covering mild-to-moderate and severe anxiety. Of the fifty women enrolled, forty-four were in the former category and six in the latter. The authors reported that within-stratum analyses were not feasible.
Balanced assignment is not subgroup power
Stratification can support comparability when allocating treatment. It does not guarantee enough severe cases to estimate a precise treatment effect within that category. The full trial’s planned size and its overall findings should not be attributed to a subgroup containing only a few participants.
Absence of an analysis is not a severe-group null result
The study did not establish that CBD was ineffective for severe anxiety, nor that the favorable secondary comparison was driven by that subgroup. Both claims would require evidence not supplied by the reported analysis. Its population was predominantly mildly or moderately anxious women with advanced breast cancer. That distribution belongs in any application of the acute findings to people with a different severity profile or psychiatric diagnosis.
Related analysis: the study’s broader findings and limitations.
