Beck Depression Inventory
The Beck Depression Inventory (BDI: Beck et al 1996) is a series of questions developed to measure the intensity, severity, and depth of depression in patients with psychiatric diagnoses. Its long form is composed of 21 questions, each designed to assess a specific symptom common among people with depression such as pessimism, sense of failure, mood, self-dissatisfaction, guilt, punishment, self-dislike, self-accusation, suicidal ideas, crying, irritability, social withdrawal, body image, work difficulties, insomnia, fatigue, appetite, weight loss, bodily pre-occupation and loss of libido. Items 1 to 13 assess symptoms that are psychological in nature, while items 14 to 21 assess physical symptoms. Scores can range from 0 – 63, with higher scores indicating more severe depressive symptoms. Scores can be described as minimal depression (0-9), mild depression (10-18), moderate depression (19-29) and severe depression (30-63).
Patient Health Questionnaire (PHQ-9)
The Patient Health Questionnaire (PHQ) is a self-administered version of the PRIME-MD diagnostic tool for common mental disorders. The PHQ-9 is the depression component, which scores each of the 9 DSM-IV criteria as “0” (not at all) to “3” (nearly every day). It is commonly used to monitor the severity of depression and response to treatment. Reliability and validity of the tool have indicated it has sound psychometric properties. Internal consistency of the PHQ-9 has been shown to be high and studies of the measure have produced Cronbach alphas of .86 and .89 (Kroenke and Spitzer, 2001). PHQ-9 total score for the nine items ranges from 0 to 27. Scores of 5, 10, 15, and 20 represent the cut-off points for mild, moderate, moderately severe and severe depression, respectively.