What are the changes in diagnosis of other specified bipolar and related disorder across Diagnostic and Statistical Manual of Mental Disorders (DSM) 3, 4, 5, and 5-Text Revision (TR), and International Classification of Diseases (ICD) 10 and 11?

Evolution of "Other Specified Bipolar and Related Disorder" Across DSM and ICD Classifications

Direct Answer to Diagnostic Changes

The "Other Specified Bipolar and Related Disorder" category represents a fundamental shift from the vague "Bipolar Disorder Not Otherwise Specified (NOS)" categories in DSM-III and DSM-IV to more operationally defined subthreshold bipolar syndromes in DSM-5 and DSM-5-TR, while ICD-11 has moved toward dimensional symptom assessment rather than expanding categorical subthreshold diagnoses. 1, 2

DSM Evolution: From NOS to Specified Categories

DSM-III and DSM-IV Era

• Both DSM-III and DSM-IV relied heavily on the "Bipolar Disorder Not Otherwise Specified (NOS)" category, which was criticized as excessively vague and led to a large proportion of treated patients being allocated to this poorly defined group 1
• This approach resulted in systematic underdiagnosis of bipolar spectrum conditions, as clinicians lacked operational criteria for subthreshold presentations 1

DSM-5 and DSM-5-TR Changes

• DSM-5 replaced the NOS category with "Other Specified Bipolar and Related Disorder," which now requires clinicians to specify the reason the presentation does not meet full criteria (e.g., "short-duration hypomanic episodes and major depressive episodes") 1
• Several new subthreshold groups of bipolar disorders are now operationally defined rather than lumped into a single NOS category 1
• A critical restriction was added: entry criterion A now requires not only elated or irritable mood but also increased energy/activity for diagnosing hypomania or mania 1, 2
• This energy/activity requirement paradoxically shifted some patients who would have met DSM-IV criteria for Bipolar I or II into the "Other Specified" category, potentially delaying diagnosis and treatment 1, 3
• Studies demonstrate a 30-50% decrease in point prevalence of bipolar disorder diagnoses with DSM-5 compared to DSM-IV, though lifetime prevalence decreased only 6% 3

ICD Evolution: From Categorical to Dimensional

ICD-10 Approach

• ICD-10 maintained a purely categorical approach to bipolar disorders without dimensional expansions 4
• The classification lacked operational definitions for subthreshold bipolar presentations 4

ICD-11 Revolutionary Changes

• ICD-11 fundamentally restructured the entire mental disorders chapter, grouping bipolar disorders with dimensional symptom specifiers across six domains: positive symptoms, negative symptoms, depressive symptoms, manic symptoms, psychomotor symptoms, and cognitive symptoms 4, 5, 6
• Rather than expanding "Other Specified" categories, ICD-11 emphasizes rating symptom severity on a 4-point scale ranging from "not present" to "present and severe" for each domain 4
• ICD-11 added dimensional qualifiers for depressive episodes including melancholic features, anxiety symptoms, panic attacks, and seasonal pattern 4
• Severity ratings (mild, moderate, severe) and remission status (partial or full) provide nuanced characterization without creating multiple categorical subdivisions 4
• Like DSM-5, ICD-11 requires increased activity or energy in addition to mood elevation or irritability for diagnosing hypomania 7, 2

Key Harmonization Between DSM-5 and ICD-11

• Both systems now require the additional criterion of increased activity/energy for hypomania and mania diagnosis, representing the most significant point of convergence 2
• Both eliminated traditional subtypes in favor of dimensional severity specifiers 5, 6
• Both moved away from purely categorical classification toward incorporating dimensional assessment, though ICD-11 went further in this direction 4, 5

Clinical Implications and Pitfalls

Diagnostic Delay Risk

• The stricter energy/activity requirement in both DSM-5 and ICD-11 likely results in diagnostic delay and delayed early intervention for bipolar disorder 3
• Patients with prominent mood symptoms but less obvious energy changes may be misclassified into "Other Specified" categories or depressive disorders 1, 3

Field Study Performance

• ICD-11 demonstrated superior clinical utility with 82.5% to 83.9% of clinicians rating it as quite or extremely easy to use, accurate, clear, and understandable 5, 7
• Field studies showed small but measurable improvements in diagnostic accuracy with ICD-11 compared to ICD-10, though advantages were largely limited to new diagnostic categories 5
• When excluding new categories, differences in diagnostic accuracy between ICD-11 and ICD-10 were not significant 5

Practical Assessment Recommendations

• Use structured diagnostic interviews rather than unstructured clinical assessment to reduce diagnostic bias when evaluating subthreshold presentations 5
• Create detailed life charts documenting longitudinal symptom patterns, as the "Other Specified" diagnosis frequently evolves over time and may require reclassification 5
• Gather collateral information from family members, as patient insight may be limited regarding energy/activity changes during mood episodes 5
• Document dimensional symptom severity across multiple domains at each assessment using ICD-11 framework, providing flexibility for treatment planning 5

Remaining Limitations

• Both DSM-5-TR and ICD-11 remain fundamentally categorical at their core, classifying based on observable symptoms rather than underlying pathophysiology 5
• Neither system has biological validation, resulting in biologically heterogeneous groups within the same diagnostic category 6
• Changes from previous versions were relatively modest despite efforts toward dimensionality 5