The association between depressive symptoms and health status in patients with chronic pulmonary disease¹

Abstract

This study evaluated the association between depressive symptoms and health related quality of life (HRQoL) in patients with chronic pulmonary disease using both general and disease-specific HRQoL measures. A cross-sectional analysis of HRQoL measures completed by patients enrolled in the Department of Veteran Affairs Ambulatory Care Quality Improvement Project. 1252 patients with chronic pulmonary disease screened positive for emotional distress and returned the Hopkins Symptom Checklist-20 (SCL-20). 733 of 1252 had a score of 1.75 or greater on the SCL-20 indicating significant depressive symptoms. Depressive symptoms were associated with statistically significantly worse general and pulmonary health as reflected by lower scores on all sub-scales of both the Medical Outcomes Short Form-36 and the Seattle Obstructive Lung Disease Questionnaire. In fact, 11% to 18% of the variance in physical function sub-scales was attributed to depressive symptoms alone. Patients with chronic pulmonary disease and depressive symptoms reported significantly more impaired functioning and worse health status when compared to those patients without depressive symptoms. Because there are highly effective treatments for depression, selective screening of patients with chronic pulmonary disease for depression may identify a group that could potentially benefit from treatment interventions.

Introduction

Patients who suffer from chronic obstructive pulmonary disease (COPD) have been reported to have significant impairment in health-related quality of life (HRQoL) [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15]. However, the correlation between objective measures of COPD severity and outcomes on HRQoL measures has been shown to be weak to moderate. For instance, the relationship between pulmonary spirometry and HRQoL measures has been reported to be moderate to non-significant [1], [3], [5], [8], [9], [10], [15]. Spirometry measures seem to predict primarily the physical disability domain on the HRQoL [5], [9], [10]. However, other factors seem to be more associated with the different domains on HRQoL measures [3], [5], [9], [10], [13], [15].

Depressive and anxious symptoms have been reported to be associated with decreased HRQoL in patients with COPD [3], [5], [9]. Tension-anxiety symptoms have been shown to be associated with more marked decreases on a general HRQoL measure than other factors including spirometry, dyspnea, and exercise tolerance [5]. Interestingly, using a general HRQoL measure, Stewart et al reported that patients with COPD scored lower on a mental health sub-scale than patients with hypertension, diabetes mellitus, congestive heart failure, myocardial infarction, angina, arthritis and back pain. Only patients with chronic gastro-intestinal disease scored lower on mental health measures [16]. Not only are depressive and anxiety symptoms associated with decreased HRQoL in patients with COPD, but depressive and anxiety symptoms appear to be prevalent in this population. Significant depressive symptoms have been reported to range between 16–74% in patients with COPD [17], [18], [19], [20], [21].

Limitations of the literature reviewed above include that these reports: 1) have focused on symptoms of anxiety and depression as part of a validation study; 2) have only used either a general or disease-specific HRQoL measure; 3) have studied small numbers of patients, or 4) have used broad scales of psychiatric symptoms that do not focus on specific depressive symptoms or severity [3], [5], [9]. We are unaware of any reports that have addressed the association between significant depressive symptoms on both a general and disease specific HRQoL in a large sample of patients who suffer from chronic pulmonary disease.

In this paper we analyzed data from a large Veterans Affairs-funded study to more specifically address the association of depressive symptoms and HRQoL in patients with chronic pulmonary disease. We sought to answer the following questions. Using a scale that measures severity of depressive symptoms, do patients with COPD and significant depressive symptoms have worse HRQoL on both a general and disease specific measure? If patients with COPD and significant depressive symptoms do have impaired HRQoL, which domains are most affected? How much of the variance on both general and disease specific HRQoL measures is associated with depressive symptoms?