Athens Insomnia Scale: validation of an instrument based on ICD-10 criteria

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Abstract

Objectives: To describe and validate the Athens Insomnia Scale (AIS). Methods: The AIS is a self-assessment psychometric instrument designed for quantifying sleep difficulty based on the ICD-10 criteria. It consists of eight items: the first five pertain to sleep induction, awakenings during the night, final awakening, total sleep duration, and sleep quality; while the last three refer to well-being, functioning capacity, and sleepiness during the day. Either the entire eight-item scale (AIS-8) or the brief five-item version (AIS-5), which contains only the first five items, can be utilized. The validation of the AIS was based on its administration to 299 subjects: 105 primary insomniacs, 144 psychiatric patients and 50 non-patient controls. Results: Regarding internal consistency, for both versions of the scale, the Cronbach's α was around 0.90 and the mean item–total correlation coefficient was about 0.70. Moreover, in the factor analysis, the scale emerged as a sole component. The test–retest reliability correlation coefficient was found almost 0.90 at a 1-week interval. As far as external validity is concerned, the correlations of the AIS-8 and AIS-5 with the Sleep Problems Scale were 0.90 and 0.85, respectively. Conclusion: The high measures of consistency, reliability, and validity of the AIS make it an invaluable tool in sleep research and clinical practice.

Introduction

Problems with poor sleep are quite frequent in the general population; their prevalence ranges from 10% to 30% [1], [2], [3], [4], [5] and it is much higher among patients with psychiatric disorders [5], [6], [7], [8]. In most studies assessing subjective sleep difficulties, self-devised questionnaires and sleep diaries are utilized. Such instruments may be adequate for the purposes of a given study allowing comparisons between conditions or groups of individuals, but they are usually not standardized or uniform — making the integration of results from various studies impossible. Some standardized instruments, however, have been developed for the measurement of sleep difficulties in clinical settings: the Leeds Sleep Evaluation Questionnaire [9], [10], the St. Mary's Hospital Sleep Questionnaire [11], [12], the Sleep Problems Scale [13], the Pittsburgh Sleep Quality Index [14], and the Karolinska Sleep Diary [15], [16].

The evolution of diagnostic concepts regarding insomnia is reflected in the various classification systems, which have been in use over the last two decades [17], [18], [19], [20], [21]. The classification published in 1979 by the Association of Sleep Disorders Centers required a sleep laboratory based criterion of reduced sleep quantity for the diagnosis of insomnia [17]. In drafting the DSM-III-R, the clinical approach prevailed, according to which the diagnosis of insomnia is based on the patient's subjective perception of unsatisfactory sleep quantity and/or quality [18]. Ever since, for the diagnosis of insomnia impaired sleep quality is given equal importance as that of reduced sleep quantity and the patient's subjective assessment is not discarded [19], [20], [21].

Following the publication of the ICD-10 diagnostic criteria for insomnia [20], the need arose to develop a scale as a tool to assist clinicians in assessing the severity of insomnia based on these globally accepted criteria. The rationale for the development of such a tool, the Athens Insomnia Scale (AIS), has been presented previously [22]. The purpose of the present paper is to provide a detailed description of the AIS and documentation of its validation.

Section snippets

Description of the scale

The AIS is a self-administered psychometric instrument consisting of eight items (Appendix A). The first five items of the AIS (assessing difficulty with sleep induction, awakenings during the night, early morning awakening, total sleep time, and overall quality of sleep) correspond to criterion A for the diagnosis of insomnia according to ICD-10, while the requirements of a minimum frequency (at least three times a week) and duration (1 month) of any complaint correspond to criterion B of the

Results

The internal consistency measures of AIS-8 and AIS-5, based on Cronbach's α, are quite high for the total group and each subgroup of subjects (Table 2). Cronbach's α remained practically unchanged when any one of the items was removed from the calculation (α if item deleted ranging from 0.83 to 0.89). Also, the mean item–total correlation coefficients were high (0.67 for AIS-8 and 0.69 for AIS-5), with individual item values ranging from 0.53 to 0.75 (p<0.001 for each one of the correlations).

Discussion

The rationale for the development of the AIS, a scale for the assessment of insomnia according to ICD-10 principles, is based on the necessity to give appropriate importance to subjective sleep difficulty and to specify a time-frame as well as a minimum frequency for various sleep related problems [22]. In this paper, we present the validation of the AIS, based on a large sample of subjects including many users of health services with frequent sleep problems. The administration and assessment

Acknowledgements

The authors wish to express their appreciation to the members of the bilingual group of experts (Drs. V. Mavreas, G. Papadimitriou and P. Sakkas) and those of the unilingual group (Drs. D. Pappa, A. Politis and C. Psarros) for their assistance in the establishment of the equivalence of the Greek translation of the AIS to its original English text.

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