Comparison of STOP-BANG questionnaire (SBQ) & Epworth Sleepiness scale (ESS) to assess pre-test probability of Obstructive Sleep Apnoea (OSA)

Introduction: Indian prevalence of OSA is estimated at 2.4-5% in males & 1-2% in females. This mandates need of a simple but accurate tool to screen patients for OSA. Questionnaires like SBQ & ESS are effective tools but prior studies show SBQ as a better screening test for the pre-test probability of OSA using Level III monitor. Aims & objectives: To compare SBQ & ESS to assess probability of OSA. To confirm which is a better screening method. Methods: An analytical prospective study of 50 eligible patients was undertaken. They were assessed using SBQ & ESS & stratified as per the risk of OSA. They then underwent a hospital based level III portable sleep study. The Apnoea Hypopnea Index (AHI) was calculated & patients were stratified into mild, moderate & severe OSA. The correlation between SBQ scores, ESS scores & AHI was then studied along with the predictive probabilities of both questionnaires in diagnosing OSA. Results: Of the 50 patients, 90% & 70% were classified as high risk on the SBQ & ESS respectively. 78% were diagnosed OSA on the sleep study. SBQ had a high sensitivity to predict OSA (84.6%) & low specificity (54.5%) while ESS had a higher sensitivity & specificity to predict OSA being 100% & 55.6% respectively. Positive & negative predictive values of the SBQ were 88.2% & 62.5% while it was 45.7% & 100% for the ESS respectively. Conclusion: Our study observes that both STOP-BANG questionnaire & ESS help in determining the risk of OSA, ESS is a better screening parameter due to its high sensitivity & negative predictive value.