Depression in elderly outpatients with disabling chronic obstructive pulmonary disease

Age and Ageing, March, 1998 by Abebw M. Yohannes, Jamal Roomi, Robert C. Baldwin, Martin J. Connolly

Total [R.sup.2] = 0.50.

CRQ, Chronic Respiratory Questionnaire score; NEADL Nottingham extended activities of daily living score: [FEV.sub.1](%), forced expiratory volume in 1-s percentage.

(a) Household composition: 1, alone, living alone; 2, together, living with partner, child(ren) or brother(s)/sister(s).

(b) Previous occupation (social class scale).

Discussion

Previous studies have suggested a prevalence of depression in mixed-aged populations of COPD patients of around 40% [3]. In this study it was 46%. Here, the prevalence of depression exceeded that associated with other disabling conditions in patients of the same age and similar or greater levels of disability, and both were in excess of that found in normal elderly people living in the community: The null hypothesis was thus rejected.

However, it is arguable whether certain illnesses are associated with an unusually high risk for depression. For example, some studies of patients with idiopathic Parkinson's disease have found a prevalence of depression similar to that found for COPD patients in this study. It is uncertain whether the rate in idiopathic Parkinson's disease exceeds that of other chronic disorders (reviewed by Cummings [18]). In this study there was a clear difference, with an excess in COPD patients. The use of an heterogeneous comparison group may have accentuated differences but the study supports the notion of an increased vulnerability to depression in patients with COPD.

The concept of particular depressive syndromes associated with types of medical disorders has also been proposed, for example in stroke [19] and Parkinson's disease [18], but this too is controversial. Clearly being a `case' on a depression rating scale such as the BASDEC tells us little about the nature of the depression experienced and the interventions most likely to alleviate it. We are currently examining in more detail the profile of depressive symptoms in these patients using the Geriatric Mental Status Schedule [20], a structured in-depth psychiatric interview.

Our prevalence figure is close to the figure of 42% found in a `younger' elderly outpatient COPD study by Light et al. [21], which also failed to find an association between exercise tolerance and lowered mood. In the present study, poor quality of life and reduced activities of daily living were most closely associated with depression on the BASDEC. Unfortunately a cross-sectional study cannot address the direction of causality (i.e. whether poor quality of life and reduced activities of daily living lead to depression or depression leads to poor quality of life and reduced function).

One of the four dimensions of the CRQ, emotional function, contains some questions which overlap slightly with the BASDEC questionnaire. However, as the CRQ concentrates on symptoms during the 2-week period up to the day of assessment, it is unlikely that any artefactual interaction between BASDEC and CRQ would be of enough magnitude to explain the close relationship between the two scores.