Do brachycephaly and nose size predict the severity of obstructive sleep apnea (OSA)? A sample‐based geometric morphometric analysis of craniofacial variation in relation to OSA syndrome and the role of confounding factors

Abstract

Obstructive sleep apnea is a common disorder that leads to sleep fragmentation and is potentially bidirectionally related to a variety of comorbidities, including an increased risk of heart failure and stroke. It is often considered a consequence of anatomical abnormalities, especially in the head and neck, but its pathophysiology is likely to be multifactorial in origin. With geometric morphometrics, and a large sample of adults from the Study for Health in Pomerania, we explore the association of craniofacial morphology to the apnea-hypopnea index used as an estimate of obstructive sleep apnea severity. We show that craniofacial size and asymmetry, an aspect of morphological variation seldom analysed in obstructive sleep apnea research, are both uncorrelated to apnea-hypopnea index. In contrast, as in previous analyses, we find evidence that brachycephaly and larger nasal proportions might be associated to obstructive sleep apnea severity. However, this correlational signal is weak and completely disappears when age-related shape variation is statistically controlled for. Our findings suggest that previous work might need to be re-evaluated, and urge researchers to take into account the role of confounders to avoid potentially spurious findings in association studies.

Evaluation of risk factors for sleep‐disordered breathing in dogs

“…Furthermore, mandibular deficiencies and craniofacial disharmony, which includes increased anterior facial height and an inferiorly positioned hyoid, despite not being analogous to brachycephaly in dogs, can be present in humans with OSA 19,49 . In humans, brachycephaly is associated with OSA, 50 although contradictory findings exist 51 …”

“… 19 , 49 In humans, brachycephaly is associated with OSA, 50 although contradictory findings exist. 51 …”

“…19,49 In humans, brachycephaly is associated with OSA, 50 although contradictory findings exist. 51 A considerable proportion of brachycephalic dogs, 43% (12/28) had high OREI values of over 5, which is considered the threshold for OSA in adult man. 5 Low OREI values of under 5 were most prevalent in normocephalic dogs (97%, 34/35), but over half of the brachycephalic dogs also had OREI values under 5.…”

A practical, step-by-step, guide to taxonomic comparisons using Procrustes geometric morphometrics and user-friendly software (part A): introduction and preliminary analyses

“…In this case, because replicates were available, the main source of imprecision could be explored and its effect partly controlled for. Data are craniofacial 3D shapes from a European sample of several hundreds men and women (recently published, using a reduced configuration (Daboul et al 2023)). In this example, the focus is on SDM instead of population differences.…”

“…Overall, in this example, the evidence shows that euryon is very imprecise and can have an important impact on results. Thus, it seems wise to remove it (as we did in Daboul et al 2023). Generally, when, in the ME ANOVA, differences at the level of variation one is interested in (individual SDM, taxonomic differences etc.)…”