Classification of Depression According to the International Classification Diseases, Tenth Revision (ICD-10)

Waleed Ahmad

The ICD-10 has comprehensively sub-classified into various categories based on the clinical profile of symptoms and the course of symptoms. 

Based on the course, it may be a depressive episode, recurrent (major) depressive disorder, persistent depressive disorder or dysthymia, recurrent brief depression, etc. Depression may also be either unipolar or bipolar or it may occur in  

1. A first depressive episode, duration of at least15 days, is classified as a depressive episode (F32). If the first depressive episode severe and rapid onset, duration less than 15 days still depressive episode (F32).  
2. A depressive episode can be
1. mild (2 core symptoms, 2 other symptoms from the list) (32.0)
2. moderate (2 core symptoms, 3 or preferably 4 other symptoms) (32.1)
3. Severe (3 core symptoms, 4 other symptoms) without psychotic symptoms (32.2) (no delusion, hallucination or stupor)
4. Severe with psychotic symptoms (above plus either delusions, hallucinations or stupor) (F32.3)
5. Delusions can be mood-congruent or incongruent (neutral delusions e.g. delusions of reference are considered mood incongruent. None of them counts towards schizoaffective disorder unless one of the first-rank) 
6. A mild and moderate depressive episode can be 
1. with somatic syndrome (four or more somatic symptoms, or three very severe somatic symptoms)
2. without somatic syndrome (three or less somatic symptoms, not severe) 
7. A severe depressive episode always has a somatic syndrome 
8. Psychotic symptoms occur only in severe depression 
9. An episode of melancholic depression and agitated depression is coded under the severe depressive episode 
10. A single episode with atypical features→Other depressive episodes (F32.8)
11. An episode of masked depression NOS also coded under Other depressive episodes (F32.8) 
12. If depressive symptoms fluctuate/alternate with non-depressive symptoms e.g. worry, tension, distress also coded under F32.8
13. The second episode of depression changes the diagnostic category to recurrent depressive disorder (F33) 
14. A long history of typical depressive episodes, current episode hypomanic, the category remains recurrent depressive disorder (F33) 
15. Few brief hypomanic episodes but most of the episodes were depressive, the category remains the same
16. A long history of depressive episodes, current episode manic, category changes to bipolar 
17. A patient develops an episode that persists for long, fulfils criteria of depression, →persistent depression (F33.8 other recurrent mood disorders) 
18. An episode of subthreshold depressive symptoms persists for two years→dysthymia 
19. An episode of mild or moderate depression, followed by a two-year history of subthreshold depressive symptoms →dysthymia 
20. An episode of subthreshold depressive symptoms, current episode mild/moderate depression, → NOT dysthymia. Call it double depression? recurrent depressive disorder (? not clarified) current episode mild/moderate depression
21. Seasonal affective disorder coded under F33 (current mild or moderate episode only i.e. Cannot be severe) 
22. A patient has monthly episodes of depression that last less than two weeks, usually 2-3 days. Symptomatic criteria for d episode only depressive episodes can be fulfilled →recurrent be monthly episodes if depressive disorder F38.10
23. A patient has symptoms of both mania and depression which are equally prominent and fulfil criteria for depression and mania or hypomania by the number and severity of symptoms, last for two weeks→mixed affective episode 
24. A patient has symptoms of both mania and depression which alternate within hours, and fulfil criteria for depression as well as mania or hypomania by the number and severity of symptoms, the episode lasts for two weeks→mixed affective episode