Prevalence and correlates of bipolar II disorder in major depressive patients at a psychiatric outpatient clinic in Hong Kong.
BACKGROUND
Western studies indicate a high prevalence of bipolar II disorder defined by a Research Diagnostic Criteria 2-day hypomania duration criterion (30 to 61%) amongst clinically depressive patients. The situation in Chinese patients with depression is unknown.


METHODS
64 (52.5% response rate) patients first presenting to a Hong Kong public psychiatric outpatient clinic in 2005 with a diagnosis of major depression were recruited. The SCID and Family History Screen were administered.


RESULTS
DSM-IV bipolar II was found in 20.5% of depressive outpatients; 35.9% had bipolar II disorder defined by RDC 2-day duration criterion for hypomania. Family bipolarity, age of onset, and depressive recurrence distinguished bipolar II subjects from unipolar depressives irrespective of duration criteria chosen for hypomania.


CONCLUSIONS
Sample size was limited.


CONCLUSIONS
Bipolar II disorder is common amongst Chinese depressive outpatients. The evaluation method and 2-day duration criterion for hypomania were supported by bipolar validators. Replication using larger samples is needed to arrive at a more representative prevalence estimate and to enable more refined nosological evaluation.
Department of Psychiatry, Tai Po Hospital, 9 Chuen On Road, Tai Po, New Territories, Hong Kong SAR, China. arthurmak@mac.com
Arthur D P
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D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000553:Ambulatory Care; D000554:Ambulatory Care Facilities / Q000706:statistics & numerical data; D044466:Asian People / Q000523:psychology / Q000706:statistics & numerical data*; D001714:Bipolar Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D015897:Comorbidity; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005190:Family / Q000523:psychology; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D012107:Research Design / Q000592:standards