The Apnea-Hypopnea Index Underestimates Systemic Inflammation in Women with Sleep-Disordered Breathing

Background: Evidence suggests that sleep-related respiratory and related metabolic compromise may vary between females and males with sleep-disordered breathing (SDB). Our purpose was to elucidate possible gender differences in sleep-associated respiratory and inflammatory parameters in patients with SDB. Materials and Methods: A consecutive number of SDB patients (46 females and 167 males) who underwent polysomnography were retrospectively reviewed. Fibrinogen and C-reactive protein (CRP) concentration, apnea index (ApnI), hypopnea index (HypI), apnea-hypopnea index (AHI), average and minimal SpO(2), duration of snoring, age, and body mass index (BMI) were compared between sexes. Spearman's correlation coefficients between parameters were also calculated. Results: ApnI and AHI were significantly higher in males. Correlation analysis revealed striking gender differences: only in females, CRP concentration was highly correlated with snoring duration (r=0.4393), BMI (r=0.7147), minimal SpO(2) (r=-0.4357), and average SpO(2) (r=-0.4547); in females, HypI was more strongly correlated with AHI (r=0.8778), average SpO(2) (r=-0.5765), minimal SpO(2) (r=-0.5817), and fibrinogen concentration (r=0.4614) than in males (r=0.4373; -0.3295; -0.2969; and 0.0887, respectively); in females, age had a much more pronounced effect on ApnI, HypI, AHI, average oxygen saturation (SaO(2)), minimal SaO(2), snoring duration, and CRP and fibrinogen concentration. Conclusions: Respiratory compromise in females with SDB is more strongly associated with systemic inflammation than in males with SDB. Although females display a pathological AHI less frequently than males, they reach quite similar pathological SaO(2), CRP, and fibrinogen values. Therefore, AHI may underestimate the pathophysiological systemic effects of SDB in females.