Screening for depression can be problematic, since most screening instruments are long and time-consuming. The main features of depression, according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), are a two-week history of depressed mood and loss of interest in most activities. Whooley and colleagues evaluated a two-question instrument to determine its adequacy in identifying patients with major depression.
The two questions asked were as follows: (1) “During the past month, have you often been bothered by feeling down, depressed or hopeless?” and (2) “During the past month, have you often been bothered by little interest or pleasure in doing things?” The results of this two-question test were compared with those of other tests that have been substantiated to screen for depression.
Patients attending an urgent care clinic were asked to participate in the study. A self-report questionnaire and a structured interview were administered. Demographic information and any history of depression were obtained in each patient. The two questions were then asked. Subsequently, the other six validated tests were administered. A blinded review of medical records was conducted to determine whether the physician who saw the patient recognized depression in the patient.
A total of 536 patients participated in the study. The prevalence of major depression in this patient population was 18.1 percent, as determined by the National Institute of Mental Health Diagnostic Interview Schedule (a structured interview based on DSM-IV criteria). The physicians identified depression in only 8.8 percent of the patients. The two-question test had a sensitivity of 96 percent and a negative predictive value of 98 percent. The positive predictive value was 33 percent. The two-question test found 17 true positives and one false negative for every 100 patients tested.
The authors conclude that this two-question screening tool for depression is as effective as other instruments in detecting depression. If a patient answers “no” to both questions, he or she is very unlikely to have depression.
editor's note: Other studies have shown similar findings, namely that extensive instruments for depression screening may be no more effective, and certainly are more cumbersome, than simply asking a patient if he or she is or has been feeling depressed or sad. The standard instruments still have a role in identification of patients who are depressed, but a simpler test may be better in the case of screening for depression.—g.b.h.