Characteristics of eligible studies
Forty-four studies involving 5022 participants were included. The characteristics of the included studies are summarized in Supplementary Material Table 1. The earliest study was conducted in 1990, while the latest one was in 2016. The interventions included auricular acupressure and bloodletting in the auricle. The duration of the trials ranged from 20 min to 12 weeks. One trial28 made a comparison between auricular acupressure and sham acupoint, nine trials29–37 between auricular acupressure and ADs, five trials36,38–41 between auricular acupressure and no intervention, 25 trials42–66 between auricular acupressure plus antihypertensive drugs (AAPADs) and ADs alone, one trial70 between bloodletting in the auricle and no intervention, two trials68,71 between bloodletting in the auricle and ADs, three trials67–69 between bloodletting in the auricle plus ADs and ADs alone. In general, all of the trial patients had an average age of 40 years or more.