Clinical Diagnosis, DSM-5-TR, ICD-11, and Harmonization

3.2 Diagnosing and Classifying Abnormal Behavior

3.2.1 Clinical diagnosis and its utility

Before any treatment begins, a clear diagnosis of a mental disorder is required. Clinical diagnosis uses assessment data to determine whether a pattern of symptoms aligns with diagnostic criteria in established classification systems, most commonly the DSM-5-TR or the ICD-11. A diagnosis should have clinical utility, meaning it helps a mental health professional determine prognosis, shape the treatment plan, and anticipate possible outcomes of treatment. Receiving a diagnosis does not automatically mean treatment is needed; decisions depend on severity, distress, symptom salience (for example, suicidal ideation), risks and benefits of treatment, disability, and other factors. Likewise, a person may not meet full criteria yet clearly need care. The DSM notes that not showing all symptoms indicative of a diagnosis should not justify denying access to appropriate care. Symptoms that cluster together are referred to as a syndrome. If these symptoms also follow a predictable course, they are characteristic of a specific disorder. Classification systems provide an agreed-upon list of disorders with clear descriptions and criteria for diagnosis. A key concept is that disorders are considered distinct categories. For instance, delusions, hallucinations, disorganized thinking and speech, grossly disorganized or abnormal motor behavior, and negative symptoms describe a schizophrenia spectrum disorder, while a primary cognitive deficit that is acquired rather than developmental points to a neurocognitive disorder (NCD). Neurodevelopmental disorders, by contrast, manifest early in development and impair social, personal, academic, or occupational functioning. These three groups are clearly distinguished. Classification systems also enable the collection of statistics on incidence and prevalence and help satisfy insurance requirements for claims.

3.2.2 The DSM-5-TR and the ICD-11: two global classification systems

The most widely used US classification system is the Diagnostic and Statistical Manual of Mental Disorders (DSM), produced by the American Psychiatric Association (APA). The DSM is currently in its fifth edition, text revision, and is abbreviated as DSM-5-TR. The World Health Organization (WHO) publishes the International Classification of Diseases and Related Health Problems (ICD), which is in its eleventh edition and is used globally for health statistics and clinical coding. Today we begin with the DSM and then discuss the ICD.

3.2.2.1 A brief history of the DSM

The DSM has its origins in 1952 with the first edition, which introduced a glossary of diagnostic categories. Following World War II, the DSM evolved through four major editions to create a diagnostic classification system used by psychiatrists and other mental health professionals. The revision process for the DSM began in earnest in 1999, coordinated with the WHO, the World Psychiatric Association, and the National Institute of Mental Health (NIMH). This collaboration produced a 2002 monograph titled “Research Agenda for DSM‑IV.” Between 2003 and 2008, APA, WHO, NIMH, the National Institute on Drug Abuse (NIDA), and the National Institute on Alcohol Abuse and Alcoholism (NIAAA) convened thirteen international DSM‑5 research planning conferences to review literature and diagnostic areas and to prepare revisions for both DSM‑5 and ICD, with input from clinicians, researchers, consumers, and advocacy groups. A DSM‑5 Task Force chair and vice-chair were named in 2006, with work group approvals following in 2007 and 2008. An intensive six-year process then unfolded, including literature reviews, secondary analyses, drafting criteria, public postings, professional presentations, field trials, and iterative revision of criteria and text. This process involved professionals across disciplines (physicians, psychologists, social workers, epidemiologists, neuroscientists, nurses, counselors) and also sought feedback from individuals with mental disorders, families, consumer groups, lawyers, and advocacy groups. Throughout this evolution, disorders with low clinical utility or weak validity were considered for deletion, while criteria for future study were placed in a separate section, contingent on empirical support, diagnostic reliability, clinical need, and potential research benefit.

3.2.2.2 The DSM-5-TR process and language, culture, and inclusion

In spring 2019, APA began work on the DSM‑5‑TR revision, engaging more than 200 experts who conducted literature reviews of the past decade and revised the text to remove material that was out of date. Experts were organized into twenty disorder review groups, each with a section editor, plus four cross-cutting groups focusing on culture, sex and gender, suicide, and forensic concerns. An ethno-racial equity and inclusion work group reviewed material to ensure attention to risk factors such as racism and discrimination and to promote nonstigmatizing language. The DSM‑5‑TR thus emphasizes language that challenges the view of races as discrete and natural entities. Changes include using “racialized” instead of “racial” to reflect social construction; using “ethno-racial” to denote US census categories; replacing “Latino/Latina” with “Latinx” to promote gender-inclusive terminology; omitting “Caucasian” as an outdated label; avoiding “minority” and “nonwhite” to avoid reinforcing hierarchies; preferring “cultural context” and “cultural backgrounds” when referring to diversity within societies; and including data on ethnoracial groups only where reliable and representative data exist, which limited data on Native Americans due to non-representative sampling. The language changes also address gender using terms like “women and men” or “girls and boys” only when appropriate, recognizing that much information is collected based on self-identified gender. A new feature in DSM‑5‑TR is a dedicated section for each diagnosis detailing suicidal thoughts or behaviors associated with that diagnosis.

3.2.2.3 Elements of a diagnosis in DSM-5-TR

The DSM‑5‑TR identifies several key elements for making a diagnosis. Diagnostic criteria and descriptors guide diagnosis and should be informed by clinical judgment. When full criteria are met, clinicians can append severity and course specifiers to indicate the patient’s current presentation. If full criteria are not met, clinicians may use designators such as “Other Specified” or “Unspecified.” Where applicable, a record may include the severity (e.g., mild, moderate, severe, extreme) and the course type (e.g., remission, partial remission, full remission, or current). The final diagnosis integrates clinical interview data, text descriptions, explicit criteria, and clinical judgment. Subtypes denote mutually exclusive and jointly exhaustive phenomenological subgroups within a diagnosis; for example, non-REM sleep arousal disorders may be described as sleepwalking or sleep terror type, and a diagnosis such as nocturnal only versus diurnal only. Specifiers, by contrast, are not mutually exclusive or exhaustive and can be multiple; for instance, a binge eating disorder may include severity and remission specifiers. The fundamental distinction is that there can be only one subtype but multiple specifiers. Subtypes and specifiers are intended to define more homogeneous subgroups and convey information relevant to management. The DSM‑5‑TR emphasizes that a principal diagnosis is used when more than one diagnosis is present, and it typically represents the primary reason for admission or the focus of treatment. A provisional diagnosis is used when information is insufficient for a definitive conclusion but there is a strong presumption that full criteria will be met with additional information over time.

3.2.2.4 DSM-5-TR disorder categories and ICD-11

The DSM‑5‑TR covers a range of disorder categories, while the ICD‑11 organizes disorders within a broader framework of diseases and related health problems. The ICD‑11 includes a dedicated chapter for mental, behavioral, or neurodevelopmental disorders (Chapter 06). The ICD is used internationally to standardize reporting of mortality and morbidity and to support health planning, reimbursement, and research. The ICD’s global scope means that many clinical terms coded within the ICD underpin health records, billing, quality control, and epidemiological surveillance across primary, secondary, and tertiary care settings. The ICD-11 arrangement enables systematic recording, analysis, interpretation, and comparison of data across countries and over time, supports semantic interoperability, and informs decision-making in resource allocation and clinical guidelines.

3.2.2.5 The ICD-11 in practice

The ICD is designed to provide a broad foundation for health statistics and clinical coding. It supports payment systems, service planning, quality and safety administration, and health services research. Diagnostic guidance tied to ICD categories standardizes data collection and enables large-scale research and cross-national comparisons. The ICD lists disorders under the mental, behavioral, or neurodevelopmental chapter, with a structured collection of categories that align with real-world clinical presentations.

3.2.2.6 Harmonization: DSM-5-TR and ICD-11

There is an ongoing effort to harmonize DSM‑5‑TR and ICD‑11. The goals are to improve national health statistics, design better multicenter clinical trials, enhance cross-border replication of findings, and address previous misalignments between DSM‑IV and ICD‑10. Complete harmonization of DSM‑5 criteria with ICD‑11 disorder definitions has not occurred, largely due to timing differences between the DSM‑5‑TR development and the ICD‑11 revision. Nevertheless, progress has been made, as many ICD‑11 working group members participated in developing the DSM‑5 criteria, and ICD‑11 work groups were instructed to align with DSM‑5 criteria where feasible unless there were legitimate reasons not to. As a result, DSM and ICD are closer in alignment now than at any time since earlier pairings such as DSM‑II and ICD‑VIII, reflecting a significant move toward greater cross-system compatibility while preserving each system’s distinct aims and update cycles.

3.2.2.7 Full integration and practical implications

The combined use of DSM‑5‑TR and ICD-11 reflects a balance between clinical utility at the point of care and the need for consistent international statistics and research infrastructure. Clinicians should be aware that while many diagnostic criteria are harmonized, some differences remain due to timing, jurisdiction, and field-test results. This dual-system awareness supports better communication with patients, insurers, and international research collaborations, and it emphasizes the ethical and practical importance of standardization and cultural sensitivity in diagnostic practice.