Background:Preserved ratio impaired spirometry (PRISm) is characterized by decreased FEV1 (<80% predicted) without airflow limitation (FEV1/FVC?0.7). Recent studies have shown that PRISm is associated with increased risk of mortality, respiratory and cardiovascular events

Aim:To assess prevalence of PRISm in a large sample of patients evaluated for OSA and to investigate correlation with clinical and PSG parameters

Methods:In this cross-sectional study, 967 patients underwent PSG for OSA diagnosis and PFTs. All subjects were free of any respiratory disease. They were grouped according to spirometry into two groups, PRISm and normal. Demographic and PSG data were compared between groups. Multivariate regression analysis was applied to examine the effect of PRISm on OSA severity, after adjusting for age, BMI, smoking and comorbidities

Results:Among participants (mean age 55 years, 21% women, 38% current smokers), 179(19%) had PRISm and 788(81%) normal spirometry. Patients in the PRISm group were older, heavier, with higher prevalence of AF, CAD, DM and worse indices of OSA severity (all,p<0.03). PRISm showed significant independent association with AHI?30 [OR (95% CI) 1.53(1.03?2.28),p=0.04], ODI?30 [OR (95% CI) 1.52(1.01?2.28),p=0.04], mean [OR (95% CI) 0.90(0.84?0.95),p<0.01] and minimum SaO2 [OR (95% CI) 0.97(0.95?0.99),p=0.03] and TST90 [OR (95% CI) 1.003(1.000?1.005),p=0.02]

Conclusion:To our knowledge, this is the first study to examine the association between OSA and PRISm. Our results suggest a significant correlation between indices of OSA severity and PRISm. Further studies are needed to determine the role of this spirometry pattern for prediction and evolution of OSA