BACKGROUND: We sought to determine whether depressive or anxiety symptoms are associated with chronic obstructive pulmonary disease (COPD) hospitalization or mortality. These data 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. METHODS: Prospective cohort study among participants in the NETT with emphysema and severe airflow limitation who were randomized to medical therapy. Primary outcomes were 1- and 3-year mortality, as well as COPD or respiratory-related hospitalization or emergency department visit during the 1-year follow-up period. Of 610 patients randomized to medical therapy, complete data on hospitalization and mortality were available for 3 years of follow-up for 603 patients (98.9%). RESULTS: Depressive symptoms were assessed using the Beck Depression Inventory (BDI) questionnaire, and anxiety was assessed using the State-Trait Anxiety Inventory. Among 610 subjects, 40.8% had at least mild to moderate depressive symptoms. Patients in the highest quintile of BDI score (BDI score, >or=15) had an increased risk of respiratory hospitalization in unadjusted analysis compared with patients in the lowest quintile (BDI score, < 5) (odds ratio [OR], 2.26; 95% confidence interval [CI], 1.30-3.93). After adjustment for disease severity, this relationship was no longer statistically significant. The adjusted risk of 3-year mortality was increased among those in the highest quintile of BDI score (OR, 2.74; 95% CI, 1.42-5.29) compared with those in the lowest quintile. Anxiety was not associated with hospitalization or mortality in this population. CONCLUSIONS: Depressive symptoms are common in patients with severe COPD and are treated in few subjects. Depressive symptoms are associated with increased risk for 3-year mortality but not 1-year mortality or hospitalization.