Elsevier

Sleep Medicine

Volume 10, Issue 9, October 2009, Pages 952-960
Sleep Medicine

Fast Track Article
Epidemiological and clinical relevance of insomnia diagnosis algorithms according to the DSM-IV and the International Classification of Sleep Disorders (ICSD)

https://doi.org/10.1016/j.sleep.2009.07.008Get rights and content

Abstract

Background

Although the epidemiology of insomnia in the general population has received considerable attention in the past 20 years, few studies have investigated the prevalence of insomnia using operational definitions such as those set forth in the ICSD and DSM-IV, specifying what proportion of respondents satisfied the criteria to reach a diagnosis of insomnia disorder.

Methods

This is a cross-sectional study involving 25,579 individuals aged 15 years and over representative of the general population of France, the United Kingdom, Germany, Italy, Portugal, Spain and Finland. The participants were interviewed on sleep habits and disorders managed by the Sleep-EVAL expert system using DSM-IV and ICSD classifications.

Results

At the complaint level, too short sleep (20.2%), light sleep (16.6%), and global sleep dissatisfaction (8.2%) were reported by 37% of the subjects. At the symptom level (difficulty initiating or maintaining sleep and non-restorative sleep at least 3 nights per week), 34.5% of the sample reported at least one of them. At the criterion level, (symptoms + daytime consequences), 9.8% of the total sample reported having them. At the diagnostic level, 6.6% satisfied the DSM-IV requirement for positive and differential diagnosis. However, many respondents failed to meet diagnostic criteria for duration, frequency and severity in the two classifications, suggesting that multidimensional measures are needed.

Conclusions

A significant proportion of the population with sleep complaints do not fit into DSM-IV and ICSD classifications. Further efforts are needed to identify diagnostic criteria and dimensional measures that will lead to insomnia diagnoses and thus provide a more reliable, valid and clinically relevant classification.

Introduction

Insomnia has been frequently studied in the general population of Western Europe and North America [1]. Few studies, however, have used well-defined criteria to assess insomnia; its presence relies mainly on positive answers to general questions about difficulties in initiating or maintaining sleep. Sometimes frequency or severity gradations have additionally been used to determine the presence of insomnia. Some epidemiological studies have investigated the occurrence of mental disorders in relation to insomnia symptoms, mainly with the use of anxiety or depression scales [1]. A high co-occurrence of insomnia symptoms and mental disorders has been reported in the general population [2], [3], [4], [5]. But few of these studies have applied an operational definition of insomnia, although current classifications, such as the DSM-IV [6], the International Classification of Sleep Disorders [7] and the International Classification of Diseases [8], provide guidelines to assess insomnia. Each classification uses a funnel-shaped structure from a huge to a narrow definition: criteria, syndromes, episodes and diagnoses. “Criteria” refer to a set of symptoms or a guideline in a given diagnosis.

“Insomnia” (like “pain”) has different meanings depending on the clinical picture presented by the subject. It can be a complaint (related to sleep quantity or quality), a symptom (part of a sleep disorder or of a mental or organic disorder) or a sleep disorder diagnosis (primary or secondary) implying the need for a differential diagnosis process. This distinction has been attempted in some epidemiological studies [2], [3], [4], [5], [9]. The clinical symptoms of insomnia, as described by the classifications, apply to a large part of the general population. It is unlikely, however, that all of these individuals suffer from an insomnia disorder [1]. Previous studies [3], [10] have indicated that sleep dissatisfaction could be a better indicator of sleep pathology than insomnia criteria used by classifications like DSM-IV and the ICSD. Consequently, this report aims to document the prevalence of insomnia not only at the criterion level, but also at the complaint level and at the diagnosis level (positive and a differential diagnosis). The final objective will be to show how the differential diagnosis evaluation could be essential to recognizing the true prevalence of insomnia and to improving clinical utility of insomnia diagnoses.

Section snippets

Sample

Individuals from seven European countries (France, the United Kingdom, Germany, Italy, Portugal, Spain and Finland) were interviewed by telephone about their sleeping habits, sleep and health (mental and physical). Information about current medications (psychotropics, prescribed medications and over-the-counter drugs) was also collected, along with the indications as reported by the subject. In each country, a representative sample was drawn from the non-institutionalized population (Table 1).

Demographic characteristics

Demographic characteristics for the whole sample are presented in Table 2. Gender and age distribution were comparable among the countries studied. The Italian, Spanish and Portuguese samples had lower rates of separated or divorced subjects than in other countries. A higher proportion of homemakers was found in the Italian and Spanish samples and, consequently, a lower rate of daytime workers compared to the other samples.

At the complaint level

Surveyed subjects slept on average 7 h 9 min. The youngest subjects slept

Insomnia diagnosis (disorder) prevalence has been under-investigated in the general population

Epidemiological studies in the general population have assessed mainly insomnia symptomatology and, on rare occasions, have used sets of criteria to determine the prevalence and severity of insomnia diagnoses (disorders) [2], [3], [9]. Furthermore, there has been no attempt to frame a differential diagnostic process to arrive at reliable insomnia diagnoses. Therefore, this large-scale study is the first to explore insomnia criteria and sleep complaints with respect to the positive and

Conclusions

Our data illustrate the importance of undertaking epidemiological studies of insomnia at several levels: complaint, criterion and diagnosis of a disorder. The distinction among these levels is of major interest:

  • (1)

    “Complaint” reflects population demand in term of needs and can be used to evaluate the efficiency of health care providers in recognizing and meeting these needs. Study at the level of complaints may also aid in understanding the motives behind help-seeking and how help-seeking relates

Acknowledgements

Funding/Support: This study was supported by National Institutes of Health Grant R01NS044199 (Dr. Ohayon); UPMC (University of Pittsburgh Medical Center) Endowment in Geriatric Psychiatry (Dr. Reynolds) and P30 MH71977 (Dr. Reynolds).

Role of the sponsor: The sponsors had no influence on the design, conduct, or analysis of this study.

Data access and responsibility: The first author (Dr. Ohayon) takes responsibility for the integrity of the data and the accuracy of the data analysis. All authors

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