## 4 Discussion
According to the results of [PERSON] et al., the questionnaire can be used with 86% sensitivity and 77% specificity for estimation of respiratory disturbance index (RDI) above 5, and 54% sensitivity and 97% specificity for estimation of RDI above 15 [47]. In a study by [PERSON] et al., the prediction of AHI above 15/h was found to have 58.8% sensitivity and 77.6% specificity, with a negative predictive value of 82.9% [48]. These results are in line with findings of [PERSON] et al., who estimated 89% sensitivity and 63% speci-ficity in the case of this questionnaire [49]. According to other sources [48], if the questionnaire was used to predict AHI above 30, 76.9% sensitivity, 72.7% specificity and 96.3% negative predictive value were observed [48]. In our study, OSA/non-OSA categorization by AI, based on the Berlin questionnaire, was found to be successful in 62% of cases, similarly to the result observed for severity subgrouping (61%). The questionnaire performed worst when identifying non-OSA cases while being used for the non-OSA/OSA binary grouping (19.40%). It can be concluded that the low specificity of the questionnaire prevents it from being suitable for use in our research for identifying non-OSA cases in binary groupings. At the same time, it can be concluded that subcategorization by severity was most successful for non-OSA prediction (72.22%), while it was the weakest for mild OSA classification (50%). Using AI based on just the simple sum of scores of the questionnaire, 42% of the non-OSA group patients obtained a low probability of OSA, while 22% of the mild OSA group and 34% of the moderately severe-severe OSA group proved to have a high probability of OSA. The explanation of these results could be the significant difference between the non-OSA and mild, and the non-OSA and moderately severe-severe OSA subgroups. In other words, using the Berlin questionnaire with AI significantly improved predictive power in all severity subgroups. Another widely used form of self-completion questionnaire is the Epworth questionnaire. Several studies have been conducted to investigate the screening of OSA with the questionnaire, to study its sensitivity, specificity and positive and negative predictive value. Results of 11 studies involving 47 to 4770 subjects with AHI above 30 events/hour found the sensitivity of the questionnaire to be between 46 and 79%. Its specificity was found to be highest for mild OSA (75%), with positive and negative predictive values above 80% [50]. In a study involving 1450 participants, the sensitivity of the questionnaire was also found to be around 50% for AHI groups above 5, 15 and 30 events/hour, while its specificity averaged 60% [48]. In our study, the patient population with AI, OSA and non-OSA categorization by the Epworth questionnaire was successful in 75% of cases, and the OSA prediction severity category in 56%. The highest success rate was found in the mild OSA group, with a success rate of 96.87% in predicting OSA, while in the moderately severe-severe OSA group, a success rate of only 18.75% was found. Our results, without the use of AI, showed that daytime sleepiness was present in 77% of the patients in the non-OSA group. Patients in the mild OSA group had mild daytime sleepiness in 19% of cases, moderate in 28% and severe in 13%. The moderately severe-severe OSA group experienced mild daytime sleepiness in 19% of cases, moderate in 44% and severe in 28%. In grouping the OSA/non-OSA subgroups, the Epworth excelled over the Berlin questionnaire. When grouping according to severity, however, the Berlin questionnaire produced the more accurate result. The fruitfulness of prediction of the Epworth questionnaire using AI may be severely decreased by the fact that there was no significant difference between the OSA severity subgroups that could explain the weaker predictive power of the Epworth questionnaire compared to the one seen at the Berlin questionnaire. The above finding highlights the weaker prediction power of the Epworth questionnaire for moderately severe-severe OSA.