Systemic inflammation in patients with compromised upper airway anatomy and primary snoring or mild obstructive sleep apnea

Our aim was to study associations between serum fibrinogen and C-reactive protein (CRP) levels and respiratory parameters on polysomnography (PSG) in patients with snoring as their main complaint and compromised upper airway anatomy. In this retrospective study, consecutive patients (43 female and 132 male; age range 11–82 years, respiratory distress index—RDI range 0.1–94.4/h) with snoring as their main complaint and compromised upper airway anatomy who underwent PSG were assessed. Spearman’s Rho coefficients between RDI, AI (apnea index), hypopnea index (HI), average and lowest SpO₂ (in %) and CRP- and fibrinogen serum levels were calculated. Comparisons between groups were made using Wilcoxon-W test. Patients with CRP > 5 mg/dl (22 % of the cohort) had significantly increased RDI, AI, average and lowest SpO₂ than patients with CRP < 5 mg/dl. Increased correlation coefficients were observed for average SpO₂ (−0.386), RDI (0.355), lowest SpO₂ (−0.323) and AI (0.309). Patients with fibrinogen >350 mg/dl (in 33 %) had significantly increased RDI, HI, AI, average and lowest SpO₂ than patients with fibrinogen <350 mg/dl. Increased correlation coefficients were found for average (−0.340) and lowest (−0.268) SpO₂, RDI (0.236) and AI (0.229). Even patients with RDI < 15/h had increased serum CRP—(in 11 %) and/or fibrinogen—(in 19 %) levels. Simultaneous elevation of both CRP and fibrinogen levels occurred only in patients with RDI > 5/h. Systemic inflammation is strongly associated with average and lowest SpO₂, RDI and AI (and with HI) in snorers with compromised upper airway anatomy and is present even in patients with primary snoring and mild obstructive sleep apnea.