Diagnostic Criteria for Persistent Depressive Disorder

Definition and Classification

The American Psychiatric Association conceptualized dysthymia as a distinct chronic mood disorder, separate from major depressive disorder, requiring symptom duration of less than 6 months to distinguish it from other depressive presentations 1
The World Health Organization maintained dysthymia as a separate diagnostic entity using a purely categorical approach without dimensional expansions, requiring at least four out of ten symptoms with two being core symptoms (depressed mood, loss of interest, or increased fatigability) 4

The International Classification of Diseases (ICD-11) added dimensional qualifiers for depressive episodes including melancholic features, anxiety symptoms, panic attacks, and seasonal pattern 4, 2
The ICD-11 Committee determined that evidence was insufficient to support combining dysthymic disorder and chronic major depressive disorder into a single category, and instead maintained dysthymia as a separate diagnostic category 4

Field studies revealed that interrater reliability for dysthymic disorder in ICD-11 was "improvable" despite overall improvements over ICD-10, with 82.5% to 83.9% of clinicians rating ICD-11 as quite or extremely easy to use 4, 5
Diagnostic accuracy and clinical utility were higher for ICD-11 compared to ICD-10 in comprehensive field studies with 928 clinicians, though advantages were largely limited to new diagnostic categories 5, 3