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How to approach baseline imbalance in cross-randomised studies?

Published:December 05, 2022DOI:https://doi.org/10.1016/j.autneu.2022.103020
      Höper and colleagues have recently published the results of their study on the influence of transcutaneous auricular vagus nerve stimulation (tVNS) on prefrontal cortex oxygenation and autonomic nervous system (ANS) activity in adolescents. In a within-subject-cross-randomised and sham-controlled study, they compared 15-minute electrical stimulation at the concha (tVNS) with stimulation at the ear lobe (sham) and measured heart rate (HR) and heart rate variability (HRV) as indexes of ANS activity. They found an increase in HRV and a decrease in HR during tVNS compared to sham and proposed a therapeutic potential of tVNS for disorders associated with altered ANS functioning (
      • Höper S.
      • Kaess M.
      • Koenig J.
      Prefrontal cortex oxygenation and autonomic nervous system activity under transcutaneous auricular vagus nerve stimulation in adolescents.
      ). However, we believe there could be a potential bias in the intervention effect estimates due to baseline imbalance. We appreciate a revisiting of the data and additional statistical analysis for a better understanding of the results and methodological challenges in the field.
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