The relationship between craniofacial morphology and obstructive sleep apnea in whites and in African-Americans

Previous studies of craniofacial risk factors for obstructive sleep apnea (OSA) have been based predominantly on cephalometry. However, differences in head form (measured by the cranial index [CII) and facial form (measured by the facial index [FI]) are considered by anthropologists to provide a basis for structural variation in craniofacial anatomy. We assessed the association of head and facial form with the apnea hypopnea index (AHI) in 364 white individuals and 165 African-Americans. Data collected included cranial and facial dimensions (using anthropometric calipers), body mass index (BMI), neck circumference, and the AHI. CI and FI differed for whites with OSA (AHI greater than or equal to 15) versus those without OSA (AHI < 5) (increased CI and decreased FI in subjects with OSA, p = 0.005 and p = 0.006, respectively). CI and FI did not differ in OSA versus non-OSA groups of African-Americans. In subjects with OSA, the CI in whites was again greater and the Fl smaller than those in African-Americans (p = 0.007 and p = 0.004, for CI and Fl.) We conclude that brachycephaly is associated with an increased AHI in whites but not in African-Americans. The CI may useful in phenotyping and identifying population subsets with OSA.