COPD Exacerbations Linked to Depression and Anxiety

By Crystal Phend
MONTREAL, 02 nov 2008-- Depression may cause exacerbations of chronic obstructive pulmonary disease, and anxiety prolongs them, researchers said. COPD patients with symptoms of depression were at a 51% to 56% increased risk of exacerbations and a 72% increased risk of hospitalization, reported Jean Bourbeau, M.D., of McGill University here, and colleagues in the Nov. 1 issue of the American Journal of Respiratory and Critical Care Medicine. The prospective, longitudinal study also showed that exacerbations lasted almost twice as long for patients with pre-existing anxiety symptoms. A comprehensive evaluation of confounding suggested that the associations were likely causal, although Dr. Bourbeau emphasized the need for caution in talking about causal relationships.
Since better detection and treatment of depression in COPD patients could improve clinical outcomes, the findings provide a further argument for treating depression in these patients, he said.
Like other chronic diseases, COPD is frequently seen with comorbid depression and anxiety, the researchers said.
For chronic conditions like diabetes and hypertension, increasing evidence suggests that depression and anxiety directly impact health rather than merely being consequences or markers of disease severity, they noted.
To see whether the same was true for COPD, the researchers conducted a prospective cohort study of 491 adults with stable COPD seen at the respiratory departments of 10 general hospitals in Beijing.
All participants completed questionnaires on baseline anxiety and depression using the Hospital Anxiety and Depression Scale (HADS) and were followed monthly by telephone over a 12-month period for subsequent exacerbations and other clinical events.
Depression was probable for 9% of patients based on HADS depression scores above 11 at baseline. Anxiety was also probable for the 5.1% of patients with HADS anxiety scores greater than 11.
After adjustment for known confounders and COPD severity, depression showed a significant dose-response association with clinical events.
Compared with nondepressed patients who had HADS depression scores below seven, probable depression was associated with an increased risk of the following:
Exacerbations with worsening of dyspnea or sputum amount, color or purulence (incidence rate ratio 1.51, 95% confidence interval 1.01 to 2.24).
Exacerbations with worsening symptoms and a change in antibiotics, corticosteroid, or bronchodilator medication (IRR 1.56, 95% CI 1.02 to 2.40).
Hospitalization (IRR 1.72, 95% CI 1.04 to 2.85).
These associations remained significant after adjustment for lung function measured by FEV1% and grade of dyspnea, although not consistently so after controlling for baseline six-minute-walk distance.
Although anxiety was not linked to exacerbation incidence or hospitalization, it was associated with a 1.92 times longer duration of exacerbation than was seen among those with no anxiety as indicated by scores below seven (95% CI 1.04 to 3.54).
Hospitalizations also tended to be longer -- 2.45 times longer with probable depression (95% CI 0.76 to 7.87) and 1.99 times longer with probable anxiety (95% CI 0.59 to 6.72) -- but the associations were not significant.
Possible mechanisms to explain the effect of depression on COPD exacerbation suggested by Dr. Bourbeau's group included:
Immune effects of depression that may impact susceptibility to environmental triggers of COPD exacerbation, such as viral or bacterial infection and air pollutants.
Reduced ability to adapt to having a chronic illness and increased awareness of and focus on physical symptoms.
Lower self-confidence and a feeling of hopelessness leading to poor self-care and adherence to medications that may make them more vulnerable when exposed to a trigger of COPD exacerbation.
Limitations of the study included an 8% dropout rate, which was higher among patients with more severe COPD, and other possible unmeasured confounders.
Further study is needed to confirm the findings and determine whether intervention to treat depression and anxiety may reduce exacerbations and improve health resource utilization, the researchers said.
The study was supported by the Canadian Institute of Health Research through the Global Health Research Initiative.
The researchers reported no conflicts of interest.
Primary source: American Journal of Respiratory and Critical Care MedicineSource reference:Xu W, et al "Independent Effect of Depression and Anxiety on Chronic Obstructive Pulmonary Disease Exacerbations and Hospitalizations" Am J Respir Crit Care Med 2008; 178: 913-920.