title: Independent effect of depression and anxiety on chronic obstructive pulmonary disease exacerbations and hospitalizations.
abstract: BACKGROUND
  Depression and anxiety are significant comorbid and potentially modifiable conditions in chronic obstructive pulmonary disease (COPD), but their effects on exacerbations are not clear.
  
  
  OBJECTIVE
  To investigate the independent effect of depression and anxiety on the risk of COPD exacerbations and hospitalizations.
  
  
  METHODS
  A multicenter prospective cohort study in 491 patients with stable COPD in China. Multivariate Poisson and linear regression analyses were used, respectively, to estimate adjusted incidence rate ratios (IRRs) and adjusted effects on duration of events.
  
  
  RESULTS
  Depression and anxiety were measured using the Hospital Anxiety and Depression Scale (HADS) at baseline. Other measurements included sociodemographic, clinical, psychosocial, and treatment characteristics. Patients were then monitored monthly for 12 months to document the occurrence and characteristics of COPD exacerbations and hospitalizations. Exacerbation was determined using both symptom-based (worsening of > or =1 key symptom) and event-based definitions (> or =1 symptom worsening plus > or =1 change in regular medications). A total of 876 symptom-based and 450 event-based exacerbations were recorded, among which 183 led to hospitalization. Probable depression (HADS depression score > or = 11) was associated with an increased risk of symptom-based exacerbations (adjusted IRR, 1.51; 95% confidence interval [CI], 1.01-2.24), event-based exacerbations (adjusted IRR, 1.56; 95% CI, 1.02-2.40), and hospitalization (adjusted IRR, 1.72; 95% CI, 1.04-2.85) compared with nondepression (score < or = 7). The duration of event-based exacerbations was 1.92 (1.04-3.54) times longer for patients with probable anxiety (HADS anxiety score > or = 11) than those with no anxiety (score < or = 7).
  
  
  CONCLUSIONS
  This study suggests a possible causal effect of depression on COPD exacerbations and hospitalizations. Further studies are warranted to confirm this finding and to test the effectiveness of antidepressants and psychotherapies on reducing exacerbations and improving health resource utilizations.
authors.affiliation: Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, Canada.
authors.forename: Wanning
authors.initials: W
authors.lastname: Xu
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Collet
authors.forename: Stanley
authors.initials: S
authors.lastname: Shapiro
authors.forename: Yingxiang
authors.initials: Y
authors.lastname: Lin
authors.forename: Ting
authors.initials: T
authors.lastname: Yang
authors.forename: Robert W
authors.initials: RW
authors.lastname: Platt
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
authors.forename: Jean
authors.initials: J
authors.lastname: Bourbeau