Validation of a Korean Version of the Insomnia Severity Index

Abstract

Background and PurposeThe purposes of this study were to standardize and validate a Korean version of the Insomnia Severity Index (ISI-K), and to evaluate its clinical usefulness.MethodsWe translated the ISI into Korean and then translated it back into English to check its accuracy. The 614 patients with sleep disorders who were enrolled in this study comprised 169 with primary insomnia, 133 with comorbid insomnia, and 312 with obstructive sleep apnea. All subjects underwent one night of polysomnography (PSG) and completed the Korean versions of both the Pittsburgh Sleep Quality Index (PSQI-K) and the Epworth Sleepiness Scale, as well as the ISI-K. The ISI-K was compared to these sleep scales and various PSG sleep parameters.ResultsThe internal consistency the ISI-K total score was confirmed by a Cronbach's alpha of 0.92, and the item-to-total-score correlations (item-total correlations) ranged from 0.65 to 0.84, suggesting adequate reliability. The correlation between the ISI-K total score and PSQI-K was 0.84, which suggested adequate convergent validity. Low-to-moderate correlations were obtained between the ISI-K total score and PSG-defined sleep parameters: 0.22 for sleep onset latency, 0.38 for wake after sleep onset, and 0.46 for sleep efficiency. A cutoff score of 15.5 on the ISI-K was optimal for discriminating patients with insomnia. The test-retest scores over a 4-week interval with 34 subjects yielded a correlation coefficient of 0.86, suggesting excellent temporal stability.ConclusionsThe findings of this study show that the ISI-K is a reliable and valid instrument for assessing the severity of insomnia in a Korean population.

Quality of life in patients with obstructive sleep apnea

“…Lee at al. 22 found that insomnia was more common (35.5%) in patients with OSA compared to 22.8% of the Korean general population 23 and that the presence of insomnia symptom had negative effects on the total scores of SF-36 only in men but not in women. Silva et al 24 showed in their 5-year follow-up study that a longitudinal increase in the difficulty initiating and maintaining sleep was associated with a decline in mental but not physical components of QoL.…”

Two subtypes of positional obstructive sleep apnea: Supine-predominant and supine-isolated

“…In order to fully characterize POSA and its subtypes, all subjects were asked to complete a series of standardized sleep related and psychometric tests including the Korean version of the Insomnia Severity Index (ISI-K) (Cho et al, 2014), the Pittsburgh Sleep Quality Index (PSQI-K) (Sohn et al, 2012), the Epworth Sleepiness Scale (ESS-K) (Cho et al, 2011), the Beck Depression Inventory-2 (BDI-2-K) (Sung et al, 2008), the Hospital Anxiety and Depression Scale (HADS) (Zigmond and Snaith, 1983), and the Korean version of the Short-Form 36-Item Health Survey (SF-36-K) (Han et al, 2004).…”

Cognitive Behavioral Therapy Using a Mobile Application Synchronizable With Wearable Devices for Insomnia Treatment: A Pilot Study

“…Participants were asked to complete the Korean version of Insomnia Severity Index (ISI) 18 and Pittsburgh Sleep Quality Inventory (PSQI) 19 based their symptoms during the previous week. The Korean version of the Dysfunctional Beliefs and Attitudes about Sleep, 20 Beck Depression Inventory, 21 and Beck Anxiety Inventory 22 were also administered.…”