Development of a Japanese version of the Epworth Sleepiness Scale (JESS) based on item response theory.
BACKGROUND
Various Japanese versions of the Epworth Sleepiness Scale (ESS) have been used, but none was developed via standard procedures. Here we report on the construction and testing of the developer-authorized Japanese version of the ESS (JESS).


METHODS
Developing the JESS involved translations, back translations, a pilot study, and psychometric testing. We identified questions in the ESS that were difficult to answer or were inappropriate in Japan, proposed possible replacements for those questions, and tested them with analyses based on item response theory (IRT) and classical test theory. The subjects were healthy people and patients with narcolepsy, idiopathic hypersomnia, or obstructive sleep apnea syndrome.


RESULTS
We identified two of our proposed questions as appropriate replacements for two problematic questions in the ESS. The JESS had very few missing data. Internal consistency reliability and test-retest reliability were high. The patients had significantly higher JESS scores than did the healthy people, and higher JESS scores were associated with worse daytime function, as measured with the Pittsburgh Sleep Quality Index.


CONCLUSIONS
In Japan, the JESS provides reliable and valid information on daytime sleepiness. Researchers who use the ESS with other populations should combine their knowledge of local conditions with the results of psychometric tests.
Takegami
Misa
M
Department of Epidemiology and Healthcare Research, Graduate School of Medicine and Public Health, Kyoto University, Yoshida konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan. takegami-kyt@umin.ac.jp
Suzukamo
Yoshimi
Y
Wakita
Takafumi
T
Noguchi
Hiroyuki
H
Chin
Kazuo
K
Kadotani
Hiroshi
H
Inoue
Yuichi
Y
Oka
Yasunori
Y
Nakamura
Takaya
T
Green
Joseph
J
Johns
Murray W
MW
Fukuhara
Shunichi
S
D000293:Adolescent; D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D020177:Idiopathic Hypersomnia / Q000150:complications / Q000175:diagnosis* / Q000523:psychology; D007564:Japan; D008297:Male; D008875:Middle Aged; D009290:Narcolepsy / Q000150:complications / Q000175:diagnosis* / Q000523:psychology; D011237:Predictive Value of Tests; D011582:Psychological Theory; D011594:Psychometrics; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000175:diagnosis* / Q000523:psychology; D011795:Surveys and Questionnaires; D055815:Young Adult