Upper airway stimulation (UAS) is shown to be effective with high adherence for patients with moderate to severe obstructive sleep apnea. However, the consistency of adherence among medical sites remains to be verified. This study examines the adherence to UAS among medical sites in an international multicenter registry. A statistically significant adherence decrease between 6-month and 12-month visit was found in the study cohort as well as in most sites. No significant heterogeneity was found among sites with either all patients or only patients who had adherence at both visits recorded. In addition, there is no enough evidence that region and experience of sites influences the adherence. This study indicates that UAS therapy adherence is consistent among sites, regardless of region and experience of sites.