Patients With COPD and Depression at Higher Risk for 3-Year Mortality

December 4, 2007 — A new study has shown that patients with severe chronic obstructive pulmonary disease (COPD) who have moderate to severe depressive symptoms are at an increased risk for 3-year mortality, with those patients scoring 15 or higher on the Beck Depression Inventory (BDI) facing the greatest risk.
Not only did the study conclude that depression is common among patients with COPD, but it also found that, for the most part, these patients are not receiving treatment for their depression. Less than one fourth of patients with depressive symptoms were receiving treatment for these symptoms.
"This study suggests that depression is under-treated among patients with COPD," said Vincent S. Fan, MD, an investigator in the Division of Health Services Research and Development at the Veterans Affairs Puget Sound Health Care System and assistant professor, Division of Pulmonary and Critical Care, University of Washington, Seattle, who was one of the study authors.
"Providers should consider screening for depression since prior research has suggested that treatment can improve respiratory symptoms and anxiety in patient with COPD," he told Medscape Psychiatry.
The new report is published in the November 26 issue of the Archives of Internal Medicine.
Depression Common in COPD
COPD is the fourth leading cause of death in the United States, the study authors write. Patients with COPD are at increased risk for depression, with prevalence among these patients estimated at between 7% and 42%. These patients also have relatively high rates of anxiety, they note, seen in 10% to 16% of this population.
The data for the current study were collected as part of the National Emphysema Treatment Trial (NETT) — a randomized controlled trial of lung volume reduction surgery vs continued medical treatment — conducted at 17 clinics across the United States between January 29, 1998, and July 31, 2002. Patients with emphysema and severe limitations of airflow in this analysis were randomized to medical therapy.
Baseline depressive symptoms were measured with the 21-item BDI, and general anxiety was measured with the State-Trait Anxiety Inventory (the State scale asks patients how they feel at a particular point in time, and the Trait scale asks them how they feel in general). Patients then completed 6 to 10 weeks of pulmonary rehabilitation before the randomization.
The analysis for this study included 610 patients. The mean BDI score was 9.3%, with 40.8% of participants scoring 10 or higher (a score usually consistent with mild to moderate depression).
Only 24.5% of patients with mild to moderate depressive symptoms were taking an antidepressant.
During follow-up, 26.9% of study subjects were hospitalized or were seen in the emergency department for COPD, and 30.5% were hospitalized for respiratory tract reasons. The overall 1-year mortality was 7.5%. During the same 1-year period, 25 patients had lung volume reduction surgery (4 later died), and 3 patients had lung transplants.
Significant Increased Mortality Risk
In these study patients, a BDI score of 10 or higher was not associated with hospitalization or mortality after adjustment for severity of disease. However, when the researchers did an analysis using BDI divided into quintiles, they did find a slightly increased risk for 3-year mortality among patients with a score of 11 to 14 vs those with a score of less than 5 (adjusted odds ratio for patients with a BDI score of 11-14 was 1.97) and a statistically significantly increased risk among those with a BDI score of 15 or higher (adjusted odds ratio was 2.74 for patients with a score of 15 or more).
This increased risk remained even after adjusting for severity of disease, something which is necessary in this patient population, said Dr. Fan. "Because patients with more severe COPD have a higher prevalence of depression, adjusting for disease severity is essential to determine the independent effect of depression," he told Medscape Psychiatry.
The study authors noted that it might be necessary to view BDI thresholds differently in patients with COPD. "Symptoms of depression such as psychomotor slowing or fatigue may overlap notably with COPD," they wrote. "Patients in the present study had a mean SD BDI score of9.3. . .suggesting that for COPD, a higher threshold for depressive symptoms may be needed compared with ischemic heart disease to identify patients at increased risk for adverse outcomes."
The researchers found no association between antidepressant use and mortality. Finally, the study also looked at anxiety and found that baseline anxiety was not associated with the risk for hospitalization or mortality at 1 or 3 years. "Although some studies had suggested that anxiety might increase the risk of COPD hospitalizations, we did not find that anxiety affected the risk of being hospitalized for an exacerbation among patients in the NETT trial," said Dr. Fan.
The study was supported by a grant from the Department of Veteran Affairs Health Service Research and Development Service and by the NETT Coordinating Center. The NETT is supported by grants from the National Heart, Lung, and Blood Institute, by the Centers for Medicare and Medicaid Services, and by the Agency for Healthcare Research and Quality. Six of the study authors have obtained funding.
Arch Intern Med. 2007;167:2345-2353.