When these 2 questions were tested in a primary care setting with patients not receiving psychotropic drugs, they had a sensitivity of 97% and a specificity of 67%.17 Other research also shows that simple questions about depression perform as well as longer questionnaires, further proof that screening for depression need not add undue length to the clinical assessment in primary care.18
Which instrument is best? Selection of a screening measure, whether it be the 2 simple questions noted above or a longer, more comprehensive tool, is the first step in the process of detecting depression in primary care settings. In making your choice, consider characteristics of the population being screened, psychometric properties of the instrument, time required to complete the measure, time required to score the measure, ease of use, and cost. A review of available screening instruments suitable for use by primary care physicians has been published in American Family Physician.19 The review includes screening measures developed specifically for adolescents, such as the Reynolds Adolescent Depression Scale, and those developed for older adults, such as the Geriatric Depression Scale.
What comes next? Making the diagnosis
Screening tools provide only a preliminary assessment. Elevated scores must be confirmed with diagnostic interviewing. Without proper follow-up, false-positive scores can lead to harmful labeling, unnecessary additional testing, and inappropriate treatment.
The diagnostic interview. Primary care physicians may feel competent to perform the diagnostic interview themselves, or they may refer patients identified by screening to a mental health professional. The interview should determine whether a patient meets the diagnostic criteria for a depressive disorder—including major depressive disorder or dysthymic disorder—found in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR).20 Bear in mind that criteria important for diagnosis, such as duration of symptoms, degree of impairment, and comorbid psychiatric or substance use disorders, are not revealed in the screening instruments.
Differential diagnosis. Depressive symptoms often overlap with medical conditions, such as hypothyroidism, and with other psychiatric illnesses, such as generalized anxiety disorder. That’s why the differential diagnosis is crucial.
Screen for bipolar disorder. Patients meeting criteria for a depressive disorder should be screened for bipolar disorder, because the 2 conditions are managed differently. Screening instruments for bipolar disorder have been less extensively studied than the depression screening instruments described earlier. The Mood Disorder Questionnaire is a brief, easy-to-use, self-report screening instrument for bipolar-spectrum disorders.21 This single-page measure screens for a lifetime history (“has there ever been a period of time”) of manic or hypomanic symptoms using 13 yes/no items, as well as 2 items assessing whether several symptoms were experienced during the same time period, and the level of functional impairment associated with such symptoms. As noted earlier, elevated scores on this and other screening instruments must be confirmed with diagnostic interviewing.
Use DSM criteria. Because of the varying clinical manifestations of depression, clinical judgment sometimes must supersede strict adherence to DSM-IV-TR criteria. Nevertheless, reliance on these well-established criteria is generally recommended as the best way to avoid over- or underdiagnosis, billing problems, and legal problems arising from an inaccurate diagnosis or inappropriate use of medications.
Treating depression
Depression is a highly treatable condition with generally good outcomes.22 A variety of antidepressant medications and psychotherapeutic modalities are available. Consensus-based guidelines have been developed to guide clinicians in the evaluation and treatment of depression.23 Remission—not simply treatment response or an improvement in symptoms—should be the targeted endpoint. STAR*D data revealed that “better but not remitted” patients consistently have a worse prognosis and higher relapse rates than those achieving full remission.8,24
Why me?
The answer: Primary care providers are the principal contacts for more than 50% of patients with mental illnesses. Approximately 35% of patients seen in primary care meet criteria for some form of depression and 10% suffer from major depression.25,26 Because individuals with depression use health care more frequently, the prevalence of major depression is 2 to 3 times higher in primary care settings than in the general population.27 Yet, a substantial proportion of primary care patients with major depression go undiagnosed, leading to a dangerous situation in which symptoms may worsen and suicidal ideation can develop.28 That’s why you, as a primary care practitioner, have such an important role to play in assessing, diagnosing, and treating depression.
Making a difference. Interventions initiated in the primary care setting have been shown to be effective for the treatment of depression.29 Findings of the STAR*D study confirm that primary care providers, when given the time, staffing, and reimbursement support, can provide high-quality, appropriate care for patients with depression, especially in uncomplicated cases.8