Anthropometric and craniofacial sexual dimorphism in obstructive sleep apnea patients: is there male-female phenotypical convergence?

Obstructive sleep apnea ( OSA) is more common in men than women. Body size is greater in males (sexual dimorphism), but large body habitus is associated with OSA for both genders. We speculated that male-female phenotypical convergence (reduced sexual dimorphism via identical phenotype acquisition) occurs with OSA and tested hypotheses: (1) phenotypical features pathogenic for OSA differ between OSA and healthy subjects irrespective of gender; and (2) such characteristics exhibit phenotypical convergence. Utilizing an existing database, we calculated male-female (group average) ratios for eight anthropometric and 33 surface cephalometric variables from 104 Caucasian OSA patients [72 males; apnea-hypopnea index (events h−1): males: 42.3 ± 24.7 versus females: 42.6 ± 26.1 ( P > 0.9)] and 85 Caucasian, healthy, non- OSA, community volunteers (36 males). Log-transformed data were analysed using a general linear model with post-hoc unpaired t-tests and significance at P < 0.0012 (Bonferroni multiple-comparison correction). OSA patients were older (56.9 ± 14.4 versus 38.0 ± 13.8 years), but there were no within-group gender-based age differences. All anthropometric variables (except height), plus cranial base width, mandibular breadth and retromandibular width diagonal were larger in gender-matched OSA versus healthy comparisons; thus satisfying hypothesis (1). Male-female ratios were mostly >1.0 across groups, but with no significant group × gender interactions no variable satisfied hypothesis (2). Thus, in this exploratory study, OSA patients had gender-common phenotypical differences to healthy subjects, but sexual dimorphism was preserved. Lack of complete phenotypical convergence may indicate gender-based critical phenotype-level attainment for OSA and/or gender-based OSA prevalence arises from factors other than those in this study. [ABSTRACT FROM AUTHOR]