What are the strengths and weaknesses of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) and International Classification of Diseases, Eleventh Revision (ICD-11) in diagnosing other specified schizophrenia spectrum and other psychotic disorders?

Diagnostic Classification of Other Specified Schizophrenia Spectrum and Psychotic Disorders

Direct Recommendation

ICD-11 demonstrates superior clinical utility and diagnostic accuracy compared to DSM-5-TR for psychotic disorders, with 82.5-83.9% of clinicians rating it as easier to use, more accurate, clearer, and more understandable in field studies, making it the preferred system for diagnosing other specified schizophrenia spectrum disorders. 1, 2

Strengths of ICD-11

Clinical Utility and Reliability

• Field studies with 873 clinicians demonstrated measurably superior diagnostic accuracy for psychotic disorders using ICD-11 compared to ICD-10, with high interrater reliability in ecological studies 3
• The dimensional symptom assessment approach across six domains (rated on a 4-point scale from "not present" to "present and severe") provides more nuanced clinical profiles beyond categorical diagnosis 4, 2
• ICD-11's dimensional profiles enhance treatment planning by informing psychotherapy selection and intensity, particularly for patients with trauma or substance abuse histories 4

Longitudinal Assessment Capabilities

• Course qualifiers allow characterization of episodicity (first episode, multiple episodes, or continuous course) and current clinical status (currently symptomatic, partial remission, full remission), capturing longitudinal patterns beyond categorical diagnosis 1, 3
• The dimensional approach allows rating symptom severity at each assessment without requiring precise temporal calculations, providing flexibility for treatment planning 3

International Harmonization

• ICD-11 was developed with enhanced global applicability and better alignment with DSM-5, though retaining distinct conceptual orientations 4, 5

Strengths of DSM-5-TR

Structural Organization

• DSM-5 eliminated schizophrenia subtypes and replaced them with dimensional assessments based on symptom severity, representing a move away from discrete categorical subtypes 6, 7
• The level, number, and duration of psychotic signs and symptoms are used to demarcate psychotic disorders from each other, providing clearer diagnostic boundaries 8

Dimensional Assessment

• DSM-5 introduced dimensional assessment of psychosis that allows for more specific and individualized patient assessment, complementing categorical diagnosis 8

Critical Weaknesses of Both Systems

Lack of Biological Validation

• Neither DSM-5-TR nor ICD-11 has biological validation, resulting in biologically heterogeneous groups within the same diagnostic category 2
• Both systems remain categorical at their core, classifying mental phenomena based on self-reported or clinically observable symptoms rather than underlying pathophysiology 3
• Current classifications have difficulties distinguishing diagnostic categories genetically and neurobiologically 1, 2

Limited Improvements Over Previous Versions

• When excluding new diagnostic categories in ICD-11, there was no significant difference in diagnostic accuracy, goodness of fit, clarity, or time required for diagnosis compared to ICD-10 1, 3
• Changes from previous versions were relatively modest despite efforts toward dimensionality 3

Field Study Limitations

• Field study samples could be biased toward practitioners positive about ICD-11, as online participants registered on their own initiative 1, 3
• Vignette studies describe prototypic cases that might not accurately reflect the complexity of real-life clinical situations 3
• Utility ratings varied significantly between countries, with high reliability for psychotic disorders in some settings but only moderate reliability in others 1

Specific Improvements Needed for Clinical Work and Research

Neurobiological Integration

• Integrate neurobiological subtyping through approaches like the Systems Neuroscience of Psychosis (SyNoPsis) project, which differentiates three behavioral domains (language, affect, motor behavior) matching three higher-order corticobasal brain systems to identify clinically and neurobiologically homogeneous subgroups 1, 2
• Develop biologically defined subgroups within existing diagnostic categories to improve care through tailored treatment selection and earlier detection 1

Enhanced Dimensional Assessment

• Expand dimensional assessment to all psychotic disorder categories, including specific domains for trauma-related symptoms and substance use severity 4
• Develop trauma-informed specifiers with dimensional ratings for dissociative symptoms, re-experiencing phenomena, and hyperarousal to improve diagnostic precision for trauma-exposed populations 4

Hierarchical Approaches

• Incorporate hierarchical dimensional models that recognize arbitrary boundaries between diagnostic categories limit reliability and validity, as suggested by the Hierarchical Taxonomy of Psychopathology (HiTOP) 1, 2
• Consider the general psychopathology factor that explains co-occurrence of symptoms across various disorders and relates to increased life impairment 1

Practical Implementation Improvements

• Mandate use of structured diagnostic interviews (SCID-5 or MINI 7.0) rather than unstructured clinical assessment to reduce diagnostic bias and improve reliability 4, 2
• Require detailed life charts documenting longitudinal symptom course and systematic documentation of symptom sequences 4, 2
• Establish protocols for gathering collateral information from family members and observers, as patient insight may be limited during acute psychotic episodes 4, 2
• Plan for mandatory longitudinal reassessment, as the diagnosis frequently evolves over time and may require reclassification as more information becomes available 3, 2

Common Pitfalls to Avoid

• Relying solely on categorical diagnosis without utilizing available dimensional assessments, which provide crucial information for treatment planning 4, 3
• Failing to document episodicity and longitudinal course, which are essential for accurate diagnosis and prognosis 1, 3
• Using unstructured clinical interviews instead of validated structured diagnostic instruments, leading to reduced reliability 4, 2
• Making definitive diagnoses without collateral information, particularly during acute psychotic episodes when patient insight is compromised 4, 2