Diagnosing Depression in Adults

Initial Screening Approach

The American College of Physicians recommends beginning screening with the 2-item Patient Health Questionnaire (PHQ-2) to assess for depressed mood and anhedonia over the past 2 weeks, and if the score is 2 or higher, proceed to the full PHQ-9 or a clinical diagnostic interview using DSM criteria 1, 2
If the PHQ-2 score is 0-1, no further screening is needed, according to the Journal of Clinical Oncology 5
If the PHQ-2 score is 2-3, proceed to the full PHQ-9 or a structured diagnostic interview, as recommended by the Journal of Clinical Oncology and the Annals of Internal Medicine 1, 5

For the general adult population, the PHQ-9 (9 items) assesses all DSM-IV major depressive disorder symptoms, with scoring as follows: 1-7 (minimal), 8-14 (moderate), 15-19 (moderately severe), 20-27 (severe), according to the Journal of Clinical Oncology 6, 7, 2
The Beck Depression Inventory (BDI, 21 items) scores 20 or higher to suggest clinical depression, assessing behavioral, cognitive, and somatic components, including suicidal ideation, as noted by the Journal of Clinical Oncology 6, 7, 8, 2
The Hamilton Rating Scale for Depression (HAM-D, 17 items) is a clinician-administered scale with scores 7-17 (mild), 18-24 (moderate), and 25 or higher (severe depression), according to the Journal of Clinical Oncology 6, 7, 8, 2
The Center for Epidemiological Studies-Depression Scale (CES-D, 20 items) scores 16 or higher to indicate moderate to severe symptomatology, relatively unaffected by physical symptoms, as recommended by the Journal of Clinical Oncology 6, 7, 8, 2

For older adults (65 years or older), the Geriatric Depression Scale (GDS) is recommended, specifically designed for elderly patients, excluding somatic symptoms that may confuse diagnosis, according to the Journal of Clinical Oncology 6, 7, 8
For patients with medical comorbidities, use screening tools that minimize somatic symptom overlap, such as the Hospital Anxiety and Depression Scale (HADS) or the CES-D, as suggested by the Journal of Clinical Oncology 6, 7, 8

Always assess for suicidal ideation, homicidal ideation, and self-harm thoughts, regardless of screening score or symptom severity, according to Praxis Medical Insights and the Journal of Clinical Oncology 10, 5
If any risk of self-harm or harm to others is identified, immediately refer for emergency psychiatric evaluation and initiate harm-reduction interventions, as recommended by the Journal of Clinical Oncology and Praxis Medical Insights 6, 11, 8, 10

All positive screening tests must trigger a full diagnostic interview using DSM criteria to confirm major depressive disorder or dysthymia, according to the Annals of Internal Medicine and Praxis Medical Insights 1, 3, 4, 9
The DSM diagnostic criteria require at least 5 of 9 symptoms present during the same 2-week period, with at least one symptom being either depressed mood or anhedonia, causing clinically significant functional impairment, as noted by the Journal of Clinical Oncology and Praxis Medical Insights 5, 10

Document how symptoms interfere with work, relationships, self-care, and daily activities, as functional impairment is crucial for determining diagnosis and severity, according to Praxis Medical Insights and the Journal of Clinical Oncology 10, 5
Moderate depression (PHQ-9 8-14) is expected to result in mild to moderate functional impairment, while severe depression (PHQ-9 15 or higher) is expected to result in moderate to marked functional impairment, as recommended by Praxis Medical Insights 10