Study objectives: This aim of this study was to determine the relative contributions of craniofacial form and anthropometric factors to obstructive sleep apnea (OSA) in two different racial groups, both markedly obese and with a similar mean respiratory disturbance index (RDI).
Design: A cross-sectional study of New Zealand Maori (Polynesian) and European (Caucasian) men with RDI> or =15, using lateral and postero-anterior cephalometric radiography.
Setting: N/A.
Patients or participants: N/A.
Measurements and results: Measurements of facial and cranial width, length and height, airway size, stature, weight, body mass index (BMI), neck circumference, RDI, and age were obtained. The Polynesian men had, on average, a greater neck circumference than the Caucasian men. There were no significant differences in age, weight, BMI or RDI between the two groups. The Polynesian men also had broader craniofacial skeletons, larger and more prognathic mandibles, greater neck extension, and some larger airway dimensions than the Caucasian men. In the Polynesian men, the width of the bony nasal aperture was positively associated with RDI, and mandibular prognathism was negatively associated with RDI. In contrast, in the Caucasian men only neck circumference was positively associated with RDI, while the retropalatal airway was negatively associated with RDI.
Conclusions: The results indicate that OSA in these two racially distinct groups is due to different etiological factors. Small reductions in mandibular prognathism and a wider bony nasal aperture were major factors associated with OSA in Polynesians. On the other hand, in the Caucasian group OSA was associated with a larger neck circumference and a reduced retropalatal airway size.