Comparability of sleep questionnaires and the possibility of binary division by the insomnia severity index

Background . Sleep disturbances significantly reduce life quality. Insomnia is one of the most common symptoms of menopause. Various questionnaires, such as the Insomnia Severity Index (ISI), the Pittsburgh Sleep Quality Index (PSQI), and the Epworth Sleepiness Scale (ESS) are considered for subjective quality assessment. Studies often use one or two questionnaires, making it difficult to compare results. Further complications are caused by differences in the number of groups which the sample is divided based on the results. To successfully compare the results of studies using different questionnaires, it is necessary to correlate the questionnaire results and standardize the groupings. The aim . To compare sleep questionnaires and determine the most appropriate cut-off point for binary distribution for ISI. Methods . Ninety-six menopausal women participated in the study. Participants taking melatonin, suffering from diabetes or cancer, or chronic diseases on acute stage, were excluded. Participants completed the Pittsburgh Sleep Quality Index (PSQI), the Insomnia Severity Index (ISI), and the Epworth Sleepiness Scale (ESS). Results were assessed and women were grouped according to standard protocols for these questionnaires. A comparison of the ISI questionnaire results (based on the four-group questionnaire modification) with the PSQI and ESS to determine the most appropriate cut-off point for obtaining a binary distribution was performed using Cohen's kappa. Results . The ISI correlates with the PSQI. The ESS should be considered as an assessment of another aspect of sleep disturbance. The cut-off point at which the ISI and PSQI groups similarity is higher was 10 points. Conclusion . Defining a specific cut-off point allows to use the ISI questionnaire when binary division is necessary.