ASSOCIATION OF SPIROMETRIC PARAMETERS AND STOP BANG SCORE WITH SEVERITY OF OBSTRUCTIVE SLEEP APNEA: AN AMBISPECTIVE OBSERVATIONAL STUDY

Abstract

Objective: Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder associated with important cardiometabolic consequences. This study aimed to evaluate the relationship between spirometric parameters, STOP BANG score, and OSA severity in patients evaluated for suspected sleep-disordered breathing. Materials and Methods: This ambispective observational study included 90 adults who underwent polysomnography, spirometry, and STOP-BANG assessment. Clinical variables included age, sex, body mass index (BMI), neck circumference, Epworth Sleepiness Scale (ESS), smoking status, apnea–hypopnea index (AHI), and forced expiratory volume in 1 second (FEV₁). OSA severity was classified as mild, moderate, or severe according to AHI. Continuous variables were summarized as mean ± standard deviation. Pearson correlation, one-way ANOVA, ROC analysis, and multivariable logistic regression were performed. Sample size was estimated assuming a moderate correlation coefficient (r = 0.30), with 80% power and 5% alpha. Results: The study population had a mean age of 54.1 ± 10.0 years and mean BMI of 30.3 ± 3.0 kg/m². Severe OSA was present in 56.7% of patients. FEV₁ showed a significant inverse correlation with AHI (r = −0.409, p < 0.001). FEV₁ also declined progressively across OSA severity groups, from 84.9 ± 13.0% predicted in mild OSA to 73.5 ± 13.1% predicted in severe OSA (p = 0.011). STOP-BANG score showed modest predictive performance for severe OSA (AUC = 0.573), while FEV₁ demonstrated better discrimination (AUC = 0.665). A combined model improved discrimination slightly (AUC = 0.672). Conclusion: Reduced FEV₁ remained independently associated with severe OSA after adjustment for age, sex, BMI, neck circumference, and STOP-BANG score. Although spirometry cannot replace polysomnography, it may provide complementary physiological information for OSA risk stratification.