Classifications of mental disorders are a necessary evil. Without a comprehensive, consensual list of the kinds of problems human beings experience, the field of mental health would be continually swamped by the task of describing the nature of each person’s problem. Communication between professionals would break down. Selecting treatments and identifying conditions for research would be a free-for-all. Tracking the burden (both societal and personal) for individuals with mental disorders would become an impossible task. Mental health classifications provide the infrastructure that allows the field to go about its business of helping people in need.
The developers of mental health classifications like the Diagnostic and Statistical Manual of Mental Disorders (DSM) and International Classification of Diseases and Related Health Problems (ICD) have always endorsed the importance of clinical utility for the manual. However, historically field studies have focused almost exclusively on the inter-rater reliability of diagnosis, and have done very little to examine a classification’s clinical utility (Clarke et al., 2013; Sartorius et al., 1993).
The World Health Organization hopes to change that trend as it works on the development of the Mental and Behavioural Disorders chapter of the 11th edition of the ICD. Among its developers, there is an explicit recognition that if a diagnostic classification system is not easily understood and applied by front line providers, public health will suffer via missed opportunities to identify and treat individuals with mental disorders. Therefore, the WHO has undertaken a series of field studies to systematically evaluate the clinical utility of the ICD-11 Mental and Behavioural Disorders with the goal of improving the usability of the manual before it is published (Keeley et al., 2016a).
The first step in this series of studies included the two largest surveys of international mental health professionals ever conducted (Reed et al., 2011; Evans et al., 2013). The surveys provided information about which classification systems professionals typically use, and how they use those systems. Three findings from these surveys are particularly noteworthy. First, professionals vastly prefer a simpler classification system with fewer rather than more diagnostic categories. Thus, the addition of any new diagnoses in ICD-11 was approached very conservatively, and an effort was made to simplify the system by eliminating or merging disorders with limited validity. Second, professionals prefer flexible guidelines that allow for the application of clinical judgment to strict criteria that maximize reliability. Third, a sizable portion of participants found several diagnoses difficult to apply across cultures, partially due to inflexible wording. Given that the ICD-11 is intended to be applied globally, special attention has been paid to increasing the cultural applicability of the disorder definitions.
The second set of studies investigated how mental health professionals organize disorders. While it may seem like an esoteric question, it has profound practical application. Clinicians’ organization of disorders operates like a road map. It helps them to navigate the complex landscape of psychopathological presentations. The table of contents for the classification provides a similar kind of organization. If the two maps do not match, finding information in the classification becomes harder and easier to miss. Two studies examining clinicians’ implicit and explicit organization of mental disorders found remarkable consistency across geographic region, language, and profession, and have helped inform the structure included in ICD-11 (Reed et al., 2013; Roberts et al., 2012).
The third set of studies are examining how clinicians apply the proposed diagnostic guidelines to help inform changes to improve the guidelines. Traditional clinic-based field studies are unable to determine the source of unreliable diagnostic decisions, and thus are limited in suggesting specific revisions. This set of studies has employed a vignette-based experimental design that allows far more specific evaluation of clinicians’ diagnostic decision-making process. It has already helped to identify portions of the diagnostic guidelines that clinicians are not able to reliably interpret or apply, leading to targeted revisions (Keeley et al., 2016b).
The final set of studies are the most familiar; they will examine how practicing professionals apply the guidelines in their daily practice. A portion of these studies will examine the inter-rater reliability of two professionals examining the same patient, while a broader range of studies will investigate the ease of use, local applicability, goodness of fit, and other important components of the clinical utility of the guidelines.
The clinical utility of a diagnostic classification, much like its validity and reliability, is a multifaceted construct that varies with the context in which it is applied. The set of studies undertaken for the ICD-11 development are aimed to provide broad coverage of the concept of clinical utility using multiple methodologies. These studies have each included representation from multiple languages, nationalities, and professions. For the first time, the development of a classification of mental disorders has made a concerted effort to evaluate and improve its clinical utility. We sincerely hope this trend will continue.
Dr. Jared Keeley is an Associate Professor of psychology at Mississippi State University. His primary interest involves the classification of psychopathology, especially concerning mental health professionals’ use of the diagnostic system. Currently, he is consulting for the World Health Organization on the field trials for the Mental and Behavioural Disorders chapter of the International Classification of Diseases (ICD) as they work towards the eleventh revision.
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Keeley, J. W., Reed, G. M., Roberts, M. C., Evans, S. C., Medina-Mora, M. E., Robles, R.,… Saxena, S. (2016a). Developing a science of clinical utility in diagnostic classification systems: Field study strategies for ICD-11 mental and behavioral disorders. American Psychologist, 71, 3-16. http://dx.doi.org/10.1037/a0039972
Keeley, J. W., Reed, G. M., Roberts, M. C., Evans, S. C., Robles, R., Matsumoto, C., … Maercker, A. (2016b). Disorders Specifically Associated with Stress: A case-controlled field study for ICD-11 Mental and Behavioural Disorders. International Journal of Clinical and Health Psychology, 16, 109-127. http://dx.doi.org/10.1016/j.ijchp.2015.09.002
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