Size and burden of mental disorders in Europe—a critical review and appraisal of 27 studies

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Abstract

Epidemiological data on a wide range of mental disorders from community studies conducted in European countries are presented to determine the availability and consistency of prevalence, disability and treatment findings for the EU. Using a stepwise multimethod approach, 27 eligible studies with quite variable designs and methods including over 150,000 subjects from 16 European countries were identified. Prevalence: On the basis of meta-analytic techniques as well as on reanalyses of selected data sets, it is estimated that about 27% (equals 82.7 million; 95% CI: 78.5–87.1) of the adult EU population, 18–65 of age, is or has been affected by at least one mental disorder in the past 12 months. Taking into account the considerable degree of comorbidity (about one third had more than one disorder), the most frequent disorders are anxiety disorders, depressive, somatoform and substance dependence disorders. When taking into account design, sampling and other methodological differences between studies, little evidence seems to exist for considerable cultural or country variation. Disability and treatment: despite very divergent and fairly crude assessment strategies, the available data consistently demonstrate (a) an association of all mental disorders with a considerable disability burden in terms of number of work days lost (WLD) and (b) generally low utilization and treatment rates. Only 26% of all cases had any consultation with professional health care services, a finding suggesting a considerable degree of unmet need. The paper highlights considerable future research needs for coordinated EU studies across all disorders and age groups. As prevalence estimates could not simply be equated with defined treatment needs, such studies should determine the degree of met and unmet needs for services by taking into account severity, disability and comorbidity. These needs are most pronounced for the new EU member states as well as more generally for adolescent and older populations.

Introduction

Despite a considerable number of regional or national epidemiological studies on single diagnoses or groups of disorders in some European states (see e.g. Weissman et al., 1992, Weissman et al., 1994, Weissman et al., 1996, Weissman et al., 1997, Weissman et al., 1999), there have so far been no systematic attempts to describe comprehensively the size and burden of mental disorders for the European Union member states. As a consequence, it is unknown what proportion of the total EU population is affected by what type of mental disorder, how many children and adolescents and how many adults or elderly citizens suffer from mental disorders and whether these estimates differ by region, country and culture. Due to the lack of previous systematic inquiries in this domain, it is also unknown in which countries and for what types of disorders epidemiological studies have ever been conducted and to what degree these studies have come to similar results and conclusions. The lack of such EU-wide information is also a core obstacle to the adequate estimation of (a) the total burden associated with these disorders (Olesen and Leonardi, 2003), (b) the degree of met and unmet needs for treatment and intervention, (c) the patterns and costs of treatment and (d) the health-economic implications and total direct and indirect costs for EU nations. Acknowledging the pressing need for such data, the European College of Neuropsychopharmacology (ECNP) and the European Brain Council (EBC) as the joint representation of professional and health care institutions for mental and neurological disorders have recently commissioned a Task Force to conduct a systematic analysis of all available epidemiological studies in the EU (http://www.ebc-eurobrain.net). The analysis should cover a wide range of mental and neurological disorders (disorders of the brain) in order to describe, and if possible estimate comprehensively, the “size and scope” of these disorders in the EU; areas needing increased future research attention should be highlighted. Furthermore, data on the burden as well as the direct and indirect costs associated with mental disorders should be critically reviewed or collected to serve as input for EU-wide cost analyses and projections.

For various reasons the estimation of the prevalence of mental disorders in the EU (i.e. how widespread is a specific disorder or a group of disorders?) is difficult: (1) EU-wide studies or systematic data collections on the prevalence of mental disorders are not available, except for a few cross-national comparisons for a restricted range of disorders. (2) The term “mental disorders” includes hundreds of different clinical conditions (DSM-IV, American Psychiatric Association, 1994; ICD-10, World Health Organization, 1993), of which only some have ever been systematically explored in epidemiological studies in the EU or elsewhere. Thus, any epidemiological study estimating the total size and burden of mental disorders is necessarily more or less incomplete. (3) It is also problematic simply to add up prevalence estimates for single disorders within or across studies, because most mental disorders are associated with one another (comorbidity; Wittchen, 1996a, Wittchen, 1996b). Thus adding up prevalences leads to double counting and inflated overall rates. (4) The diagnostic and methodological standards of community studies on mental disorders vary widely making direct comparisons difficult. (5) The wider EU consists of 25 states from different language areas, each of which with different sociodemographic and socioeconomic characteristics (OECD, 2005), different cultural, legal, social and health care system-related traditions (i.e. mental health care provider and reimbursement; Coulter and Magee, 2003), and different psychopathological traditions (i.e. diagnostic habits and definitions; Wittchen, 2001). All of these factors have been shown to complicate both the conduct of studies as well as interpretations of findings. (6) Unlike the long US tradition of fairly regular, large-scale community and general population studies with uniform methods and designs (i.e. ECA, Robins and Regier, 1991; NCS, Kessler et al., 1994; NCS-R, Kessler et al., 2004), there is no such tradition yet in the EU. Only a few EU countries (such as the UK, The Netherlands and Germany) have actually put the implementation of such national epidemiological studies high on their agenda so far.

Nevertheless, there is a considerable mass of epidemiological research in the EU. In fact, in addition to a substantial number of regional and country-specific epidemiological studies of various kinds (cross-sectional and longitudinal, community and administrative), numerous other sources of epidemiological collections are available, reflecting the extremely rich European tradition in this field (Wittchen, 2004). The core disadvantage of these data, however, is that they lack the necessary degree of standardisation concerning methods, design, constructs and instruments; thus making direct comparisons or meta-analytic approaches difficult. Some of these individual studies have already been critically reviewed elsewhere, for example in the context of international diagnosis-specific reviews (Andrade et al., 2000, Andrade et al., 2003, Bijl et al., 2003, Coulter and Magee, 2003, Fryers et al., 2004, Kessler, 2004, Sartorius et al., 1993, Vega et al., 2002, Weissman et al., 1992, Weissman et al., 1994, Weissman et al., 1996, Weissman et al., 1997, Weissman et al., 1999, Wittchen et al., 2003, Wittchen, 2004). However, none of these publications has ever addressed specifically the core questions about the availability and the consistency of prevalence findings in the European Union member states.

Beyond prevalence, the lack of systematic data and knowledge is even more pronounced with regard to data on impairments and disabilities associated with mental disorders in the EU. Such data have not only much-disputed major public health and policy implications (Narrow et al., 2002, Kessler et al., 2003), but are also essential for estimating the cost burden. Beyond the estimations from the World Health Organization's Burden of Disease study (Murray and Lopez, 1996; for the EU: Olesen and Leonardi, 2003), only few large-scale epidemiological community studies are available that provide reliable information for at least some countries and/or at least some diagnoses on work loss days (WLD), “quality of life” (Bijl and Ravelli, 2000a, ESEMeD/MHEDEA 2000 Investigators, 2002, ESEMeD/MHEDEA, 2000 Investigators, 2004b, Jacobi et al., 2004b, Kessler and Frank, 1997). Another critical area is the question to what degree mental disorders are recognized, treated and managed in the general health care sector and the mental health care specialty sector. Beyond general administrative statistics, to our knowledge no EU-wide studies are available providing some information about the number of health care contacts by sector (general health care, specialist mental health care, in- and outpatient) as well as about types of intervention (drug, psychological treatment) (Wittchen, 2004).

Against this background, the primary aims of this paper are to review systematically all available epidemiological data on a wide range of mental disorders from community studies conducted in European countries and to determine the availability and the consistency of prevalence, disability and treatment findings. A further attempt is made to estimate the total prevalence of mental disorders across all EU states and to identify areas with particularly pronounced unmet research needs.

Section snippets

Methods

A stepwise multimethod study approach was adopted consisting of (a) iterative literature searches for epidemiological publications and subsequent data analyses of published material, (b) reanalyses of existing accessible epidemiological data sets and (c) structured expert inquiries and a questionnaire survey with experts in all EU countries. We considered only those studies conducted in community samples and reporting prevalence estimates for established diagnoses of mental disorders (according

Availability of epidemiological studies in the EU

Table 1 lists 24 country-specific (combined N > 70,000 subjects) and three cross-national (combined N > 100,000 subjects) community studies meeting the inclusion criteria. In the following sections, these studies are referred to by a study number in square brackets; note: the sites from the cross-national ESEMeD project [25] are treated as three separate studies here [25a, 25b, 25c]. Along with a core reference publication for each study listed, the table also provides information about country,

Discussion

The survey identified overall a remarkable total of 27 recent epidemiological studies in the community that included over 155,000 subjects from 16 European countries. Across all these studies it is estimated that 27% of the adult (18–65 years of age) EU population (including Iceland, Norway and Switzerland) suffer from at least one mental disorder. This 12-month prevalence estimate equals an estimated total of 82.7 million subjects affected. Lifetime incidence data, available from some of these

Acknowledgements

Data collection for epidemiological issues (chair: HUW) was coordinated by the Institute of Clinical Psychology and Psychotherapy, Technische Universität Dresden (Frank Jacobi, Elke Katze, Michael Klose, Hans-Ulrich Wittchen).

The authors would like to thank the experts participating in the data collection and commenting the prevalence data for their countries: Austria: Heinz Katschnig (Medical University of Vienna, Department of Psychiatry); Belgium: Koen Demyttenaere (Afedling Psychiatrie,

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    This paper was prepared in the framework of the European College of Neuropsychopharmacology (ECNP) Task Force project on “Size and Burden of Mental Disorders in Europe” (PI: Hans-Ulrich Wittchen) supported by funds of the ECNP Council. These data also provide input for the European Brain Council (EBC; http://www.ebc-eurobrain.net) Initiative “Cost of Disorders of the Brain in Europe” (CDBE; steering committee: Jes Olesen, Bengt Jönsson, Hans-Ulrich Wittchen). The support and assistance of many colleagues is acknowledged (see appendix for a complete listing).

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