Insomnia Severity Index: psychometric properties with Chinese community-dwelling older people

This paper is a report of a study to evaluate the psychometric properties of the Chinese version of the Insomnia Severity Index.

Despite the high prevalence of insomnia in older people and its detrimental impact on well-being and healthcare costs, this problem is almost always undetected and consequently under-treated. The Insomnia Severity Index is psychometrically sound in measuring perceived insomnia severity. However, it has had very limited application in non-White populations.

An instrument validation study was carried out between October 2008 and April 2009. The Insomnia Severity Index was translated into Chinese using Brislin's model and administered to a convenience sample of 585 older Chinese people recruited from three community centres for elders. Other instruments were also administered, including the Chinese version of the Pittsburgh Sleep Quality Index and the Geriatric Depression Scale.

Cronbach's alpha of the Chinese version of the Insomnia Severity Index was 0.81, with item-to-total correlations in the range of 0.34-0.67. Construct validity was supported by its moderate relationship with the Chinese Pittsburgh Sleep Quality Index and sleep efficiency. The Chinese version of the Insomnia Severity Index also indicated more severe level of insomnia in older people who reported depressed mood on the Geriatric Depression Scale. Discriminant validity was supported as the Chinese version of the Insomnia Severity Index could discriminate poorer sleepers from normal sleepers. Exploratory factor analysis identified a two-factor structure for the Chinese version of the Insomnia Severity Index in measuring the severity and impacts of insomnia on the Chinese older people.

The Chinese version of the Insomnia Severity Index is a culturally-relevant and psychometrically-sound instrument for assessing severity and impact of insomnia in Chinese community-dwelling older people. Nurses can use this tool to assess older people's perceptions of insomnia.