SCRATCH-HTN Trial Shows Ear Stimulation Benefit Only in Severe Hypertension Subgroup

Researchers randomized 63 participants with uncontrolled hypertension already on medication to active ear-clip stimulation or sham for 30 minutes daily in weeks 1-2 then weekly for 10 weeks. The handheld device targeted the tragus to modulate autonomic nerves without invasion. Compliance was high and adverse events minimal, confirming home feasibility, yet intention-to-treat analysis showed no statistically significant between-group difference across the full cohort.

Prespecified subgroup analysis revealed larger blood pressure reductions among those entering with higher baseline readings, suggesting response depends on hypertension severity. This aligns with prior vagus nerve stimulation work in heart failure where autonomic tone shifts proved more impactful in advanced disease states. Observational data from epilepsy tVNS trials further indicate patient selection by baseline sympathetic overdrive may drive efficacy, a nuance the original coverage underplayed.

The trial's small size and short duration limit causal claims; regression to the mean or unmeasured adherence differences could explain subgroup signals. A properly powered phase 3 study restricted to stage 2 hypertension patients with ambulatory monitoring would strengthen evidence and clarify effect size thresholds needed for clinical adoption.