title: Undiagnosed bipolar disorder in patients treated for major depression in China.
abstract: BACKGROUND
  Bipolar disorder (BD) is a recurrent, complex illness and often misdiagnosed and treated as a major depressive disorder (MDD). This study set out (1) to investigate the proportion of BD in patients treated for MDD using DSM-IV diagnostic criteria; (2) to test the usefulness of the screening tool - the 32-item Hypomania Checklist (HCL-32) in Chinese patients; and (3) to assess whether MDD patients with subthreshold manic features (patients who screened positive for BD on the HCL-32, but did not meet the diagnostic criteria for DSM-IV BD as measured by Mini International Neuropsychiatric Interview (MINI)) differ from those with BD, and from those suffering from MDD without manic features in terms of basic demographic and clinical variables.
  
  
  METHODS
  A total of 1487 patients treated for MDD were consecutively examined in 13 mental health centers in China. The patients' socio-demographic and clinical characteristics were recorded using a standardized protocol and data collection procedure. The HCL-32 was self-completed by patients to identify hypomanic symptoms, and the MINI was used by clinicians to establish DSM-IV diagnoses.
  
  
  RESULTS
  The proportions of undiagnosed BD (all types), BD-I and BD-II were 20.8%, 7.9% and 12.8%, respectively. The HCL-32 had low positive predictive value (0.43). Compared to MDD patients without subthreshold manic features, MDD patients with subthreshold manic features were younger at onset, less likely to be married and had more depressive episodes on a seasonal basis, and more frequent depressive episodes overall. Compared to BD patients, MDD patients with subthreshold manic features had an older age at onset and less frequent depressive episodes and less family history of psychiatric disorders, appetite, weight gain and time spent sleeping, suicide ideation and attempts and psychotic symptoms.
  
  
  CONCLUSIONS
  At least one fifth of Chinese patients treated for MDD may have an undiagnosed BD. The HCL-32 is useful to identify broader subthreshold bipolar features. The findings need to be confirmed by longitudinal studies using more comprehensive, standardized instruments.
authors.affiliation: Mood Disorders Center, Beijing Anding Hospital, Capital Medical University, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Hu
authors.forename: Yu-Tao
authors.initials: YT
authors.lastname: Xiang
authors.forename: Gabor S
authors.initials: GS
authors.lastname: Ungvari
authors.forename: Faith B
authors.initials: FB
authors.lastname: Dickerson
authors.forename: Amy M
authors.initials: AM
authors.lastname: Kilbourne
authors.forename: Tian-Mei
authors.initials: TM
authors.lastname: Si
authors.forename: Yi-Ru
authors.initials: YR
authors.lastname: Fang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Lu
authors.forename: Hai-Chen
authors.initials: HC
authors.lastname: Yang
authors.forename: Helen F K
authors.initials: HF
authors.lastname: Chiu
authors.forename: Kelly Y C
authors.initials: KY
authors.lastname: Lai
authors.forename: Jian
authors.initials: J
authors.lastname: Hu
authors.forename: Zhi-Yu
authors.initials: ZY
authors.lastname: Chen
authors.forename: Yi
authors.initials: Y
authors.lastname: Huang
authors.forename: Jing
authors.initials: J
authors.lastname: Sun
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Wang
authors.forename: Hui-Chun
authors.initials: HC
authors.lastname: Li
authors.forename: Jin-Bei
authors.initials: JB
authors.lastname: Zhang
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000175:diagnosis* / Q000453:epidemiology; D002681:China / Q000453:epidemiology; D015897:Comorbidity; D003865:Major Depressive Disorder / Q000453:epidemiology* / Q000523:psychology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged