Validity of a novel excessive daytime sleepiness’ screening stool : the Yaoundé Sleepiness Score.

Background The subjective assessment of excessive daytime sleepiness (EDS) using Epworth sleepiness scale (ESS) has shown some limits. This study aimed to assess the validity of the Yaoundé Sleepiness Scale (YSS), a new tool for EDS screening, using ESS as reference. Methodology A 6-item questionnaire was assessed for validity features. The content validity was based on sleep physiology. Four sleep specialists approved the initial draft for face validity. A cross-sectional study was led in Lille University Hospital to assess the criterion and construct validity. Baseline data, full night recording, and sleepiness scales (YSS, ESS) were recorded. The criterion validity was assessed using the Pearson correlation between YSS and ESS and the area under the receiver operator characteristics (AUROC) curve. A graphical method was used to find the YSS threshold. We used a simple linear regression to seek the association between YSS and EDS predictors for construct validity. Results A total of 566 patients (mean age ± standard deviation = 53.1 ± 14.6 years, female = 47%) were enrolled. The mean ± standard deviation YSS and ESS were 9.8 ± 4.7 and 9.1 ± 5.3, respectively. The Pearson correlation between YSS and ESS was 0.74% (p<0.0001). The AUROC curves (95% confidence interval, 95CI) for ESS-based EDS and severe EDS prediction were 0.856 (0.829 – 0.889) and 0.871 (0.829 – 0.913), respectively. The YSS thresholds for EDS and severe EDS were 9 and 15, respectively. Using ESS as gold standard, the sensitivity and specificity for EDS and severe EDS were 92.3 (88.7 - 95.9)% and 60.6 (55.3 - 65.9)%, and 60.3 (49.0 - 71.5)% and 90.2 (87.5 - 92.9)%. The YSS significantly increased with the use of psychotropic drugs and psychiatric conditions, and significantly decreased with age. Conclusion We found a good criterion validity and an acceptable construct validity of the YSS compared with ESS. This questionnaire could be proposed as an alternative to ESS. However, these data should be confirmed by other studies, notably based on objective sleepiness tests.