Screening for Depression in Medical Settings: The Case Against Specific Scales

The prevailing view for detecting mood disorders in the presence of physical disease is to exclude somatic symptoms that might contaminate a diagnosis (See Parker and Hyatt, Chapter 10 for a presentation of this point of view). This chapter will examine whether this approach is beneficial, with a view to deciding whether new depression scales for each physical disorder (each excluding somatic symptoms) are required. There is a bidirectional relationship between depression and physical illness. New evidence suggests that among depressed individuals presenting in primary care, most have at least one comorbid psychiatric condition and at least one physical condition. At least 75% of elderly depressed patients in primary care also have a known physical illness, and in 30–50% this is of high severity. In one study only 10% of elderly depressed patients in primary care had pure depression with no comorbidity. Thus, comorbid depression should be considered ‘‘normal’’ in primary care. Some evidence suggests that those with comorbidity are less likely to have depression treatment initiated by their primary care practitioner. They are also less likely to recover from depression.9 Specific conditions such as speech disorders, arthritis, and dermatologic problems have been linked with worse outcomes of depression. The exact relationship of depression and comorbidities is complex. In one of the largest studies, Egede (2007) examined data from 30,801 adults captured in the 1999 Household National Health Interview Survey. The community prevalence of major depression was 4.7% in those without chronic medical illness but 7.7%, 9.8%, and 12% in those with one, two, or three or more chronic disorders, respectively (Fig. 11.1). Major depression was associated with significant increases in utilization, lost productivity, and functional disability. Patients with chronic medical illness and comorbid depression (and anxiety) also have significantly higher numbers of medical symptoms, even controlling for severity of disease. Around one in four people in the general population have functional disability, but in those with depression and medical comorbidity, at least three out of four have functional limitations.