Oral appliances are increasingly prescribed for patients with moderate obstructive sleep apnea (OSA) instead of nasal CPAP. However, the efficacy of oral appliances varies greatly. We hypothesized that oral appliances were not efficacious in patients with moderate OSA who were obese with oropharyngeal crowding.
Japanese patients with moderate OSA were prospectively and consecutively recruited. The Mallampati score (MS) was used as an estimate of oropharyngeal crowding. Follow-up polysomnography was performed with the adjusted oral appliance in place. Responders were defined as subjects who showed a follow-up apnea-hypopnea index (AHI) of < 5 with > 50% reduction in baseline AHI.
The mean baseline AHI was reduced with an oral appliance from 21 ± 4 to 9.8 ± 8 in 95 subjects. Thirty-five patients were regarded as responders. Logistic regression analyses revealed that both MS and BMI could individually predict the treatment outcome. When the cutoff value of BMI was determined to be 24 kg/m2 based on a receiver operating characteristic curve, 53 obese patients (ie, BMI > 24 kg/m2) with an MS of class 4 were indicative of treatment failure with a high negative predictive value (92) and a low negative likelihood ratio (0.28).
We conclude that patients with moderate OSA who are obese with oropharyngeal crowding are unlikely to respond to oral appliance treatment. This simple prediction can be applied without the need for any cumbersome tools immediately after the diagnosis of OSA.