Depression in primary care--more like asthma than appendicitis: the Michigan Depression Project

To explore the relationships between detection, treatment, and outcome of depression in the primary care setting, based upon results from the Michigan Depression Project (MDP).

A weighted sample of 425 adult family practice patients completed a comprehensive battery of questionnaires exploring stress, social support, overall health, health care utilization, treatment attitudes, self-rated levels of stress and depression, along with the Center for Epidemiologic Studies Depression Scale (CES-D), the Hamilton Rating Scale for Depression (HAM-D), and the Structured Clinical Interview for DSM-III (SCID), which served as the criterion standard for diagnosis. A comparison sample of 123 depressed psychiatric outpatients received the same assessment battery. Family practice patients received repeated assessment of depressive symptoms, stress, social support, and health care utilization over a period of up to 60 months of longitudinal follow-up.

The central MDP findings confirm that significant differences in past history, severity, and impairment exist between depressed psychiatric and family practice patients, that detection rates are significantly higher for severely depressed primary care patients, and that clinicians use clinical cues such as past history, distress, and severity of symptoms to "detect" depression in patients at intermediate and mild levels of severity. As well, there is a lack of association between detection and improved outcome in primary care patients.

These results call into question the assumption that "depression is depression" irrespective of the setting and physician, and they are consistent with a model of depressive disorder as a subacute or chronic condition characterized by clinical parameters of severity, staging, and comorbidity, similar to asthma. This new model can guide further investigation into the epidemiology and management of mood disorders in the primary care setting.