Therapeutic efficacy of an oral appliance in the treatment of obstructive sleep apnea: a 2-year follow-up.

The purpose of this study was to investigate the long-term efficacy of an oral appliance, the Karwetzky activator, on respiratory and sleep parameters in patients with obstructive sleep apnea (OSA). Those selected for this study were 26 patients polysomnographically diagnosed with mild-to-moderate OSA. They were initially treated successfully with this appliance, as documented by a second polysomnographic study after 6 to 12 weeks. Further polysomnographic registrations 6 to 12 months and 18 to 24 months later were performed for each patient wearing the appliance. For 21 patients (81%), therapeutic efficacy was maintained; 5 patients (19%) showed a deterioration in respiratory parameters. We corrected this by adjusting the device in 2 patients. The mean apnea-hypopnea index decreased significantly from 17.8 events per hour at the baseline registration to 4.2 events per hour (P <.001) after 6 to 12 weeks of treatment. After 6 to 12 months, the apnea-hypopnea index was 8.2 events per hour. The index remained at this level 18 to 24 months later, with 8.3 events per hour. Mean oxygen saturation was not improved with the activator, but the number of desaturations had decreased at the 6-to-12 week review. Again, the improvement declined with time, but the number of oxygen desaturations was still significantly decreased at 18 to 24 months (P <.01). Although the respiratory parameters remained statistically improved throughout the study (P <.01), sleep architecture did not change statistically. In most patients, therapeutic efficacy was maintained at the 2-year follow-up, although there was a tendency for effectiveness to fall over time. We concluded that the Karwetzky activator may be an effective treatment alternative for patients with mild-to-moderate OSA, but therapy requires diligent and regular polysomnographic follow-ups. Further long-term studies are needed to assess the continued efficacy of this oral appliance in treating OSA.