Risk of bipolar disorder in patients with COPD: a population-based cohort study.
Few studies have investigated the relationship between chronic obstructive pulmonary disease (COPD) and bipolar outcomes in the world. We sought to investigate the association between COPD and risk of bipolar disorder in a large national sample.



The insured aged 15 years or more with a new primary diagnosis of COPD (ICD-9: 491, 492, 494 and 496) between 2000 and 2007 were identified from Taiwan's National Health Insurance Research Database. We included individuals with an inpatient diagnosis of COPD and/or at least 1 year of two diagnoses of COPD in outpatient services. These 35,558 cases were compared to 35,558 sex-, age-, residence- and insurance premium-matched controls. We followed both groups until the end of 2008 for incidence of bipolar disorder, defined as ICD-9 codes 296.0-296.16, 296.4-296.81 and 296.89. Competing risk-adjusted Cox regression analyses were applied with adjusting for sex, age, residence, insurance premium, prednisone use, Charlson comorbidity index, diabetes, hypertension, hyperlipidemia, cardiovascular diseases, hospital admission days, outpatients' visits and mortality.



Of the total 71,116 subjects, 202 were newly diagnosed with bipolar disorder during the study period. The mean follow-up time was 6.0 (SD=2.2) years. COPD, younger age, lower economic status, lower dose of prednisone use, higher hospital admission days and higher outpatient visits were independent predictors of bipolar disorder.



COPD was associated with increased risk of bipolar disorder independent of a number of potential confounding factors in this study.
Department of Psychiatry, Lu-Tung Christian Hospital, Lukang, Taiwan; Department of Psychiatry, Changhua Christian Hospital, Changhua, Taiwan.
Pei-Jung
PJ
Tsai
Department of Psychiatry, Chung Shan Medical University Hospital, Taichung, Taiwan; Department of Psychiatry, School of Medicine, Chung Shan Medical University, Taichung, Taiwan.
Yin-To
YT
Liao
Department of Public Health, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Health Promotion and Health Education, National Taiwan Normal University, Taipei, Taiwan.
Charles Tzu-Chi
CT
Lee
Department of Neurology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
Chung-Yao
CY
Hsu
Department of Psychiatry, Chung Shan Medical University Hospital, Taichung, Taiwan; Department of Psychiatry, School of Medicine, Chung Shan Medical University, Taichung, Taiwan.
Ming-Hong
MH
Hsieh
Department of Psychiatry, Taichung Veterans General Hospital, Taichung, Taiwan.
Chia-Jui
CJ
Tsai
Department of Psychiatry, Tung's Taichung Metro Harbor Hospital, Taichung, Taiwan.
Ming-Han
MH
Hsieh
Chang Gung Medical Foundation, Chiayi Chang Gung Memorial Hospital Chiayi, Puzi City, Taiwan; Chang Gung University, Taoyuan, Taiwan. Electronic address: hjcch@yahoo.com.tw.
Vincent Chin-Hung
VC
Chen
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001714:Bipolar Disorder / Q000453:epidemiology*; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009313:National Health Programs / Q000706:statistics & numerical data; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology*; D012306:Risk; D013624:Taiwan / Q000453:epidemiology; D055815:Young Adult
Bipolar disorder; COPD; Prednisone