The evaluation of the Croatian version of the Epworth sleepiness scale and STOP questionnaire as screening tools for obstructive sleep apnea syndrome

Abstract

Purpose: Growing awareness of obstructive sleep apnea syndrome (OSAS) has increased the need for concise and reliable screening tools. The Epworth sleepiness scale (ESS) has been validated in numerous languages and ethnic groups, since it was originally designed for the English-speaking population. The STOP questionnaire was developed as a novel OSAS screening tool in surgical patients, but has not been validated in the general population. The present study was undertaken to provide reliable and validated ESS in the Croatian language and to evaluate the ESS and STOP as screening instruments for OSAS.

Methods: The Croatian version of ESS and STOP questionnaire was administered to 217 patients referred to the Split Sleep Medicine Center and 208 healthy control subjects. Test-retest reliability was investigated in 20 healthy subjects.

Results: The ESS score was significantly higher for the patients referred to the Split Sleep Medicine Center compared to the control group (8.2 ± 5.0 vs. 5.9 ± 3.8, p < 0.001). Cronbach's alpha coefficient for the ESS Croatian version was 0.84 indicating an excellent internal consistency. Reproducibility revealed no significant difference in each item or in the total ESS scores. Receiver operating curve of the ESS for identification of cases with AHI >5/h was 0.64, and for the STOP questionnaire, it was 0.84.

Conclusions: Both ESS and STOP questionnaires successfully distinguished healthy subjects from subjects with OSAS. The STOP questionnaire had better probability to correctly predict high-risk patients for OSAS compared to ESS. We propose that the STOP questionnaire could be used as an easy-to-use and accurate screening tool in identification of patients with risk for OSAS in the general population, but it has not been tested in the Croatian population yet.