Objective: To determine whether excessive daytime sleepiness (EDS) as assessed by the Epworth Sleepiness Scale (ESS) is significantly correlated with body mass index (BMI) and Apnea-Hypopnea Index (AHI) in patients suspected of OSAS and whether obesity as assessed by BMI is associated with AHI.
Design: Non-concurrent cohort study
Setting: Tertiary Private Hospital
Population: The charts of 389 patients suspected to have sleep disorders and referred for polysomnography (PSG) at the Center for Snoring and Sleep Disorders in year 2009 were reviewed. Inclusion criteria were patients aged 19 and above with complete data. A total of 238 patient charts were included in the study.
Results: The study included a total of 238 patient charts. Results showed no significant association between ESS and AHI (p-value >0.05) even when correlated with the different severities of OSAS (p-value>0.05). Sensitivity and specificity of ESS was found to be 54% and 57%, respectively, indicating that ESS is not a sensitive and specific tool to predict the presence of OSAS. These findings suggest that ESS may not be able to significantly identify patients with OSAS. However, BMI showed a significant association with ESS (p-value<0.05) representing more patients with EDS belonging to the obese category. Conversely, obese patients were twice more likely to have EDS, represented by ESS scores of >=10. BMI was also significantly associated with AHI using oneway Anova test.
Conclusion: This report concludes that the ESS alone is insufficient to identify patients with OSAS. Nevertheless, questionnaires like the ESS supplement relevant history to help diagnose patients with sleep disorders particularly OSAS. On the other hand, the ESS showed a significant association with BMI representing more obese patients had excessive daytime sleepiness. The likelihood ratio of having excessive daytime sleepiness is two times more for obese patients. BMI was also significantly associated with AHI which confirms the well established relationship of obesity with OSAS, and shows that obese patients are at higher risk for severe OSAS.