A number of self-administered questionnaires are available for assessing depression severity, including the 9-item Patient Health Questionnaire depression module (PHQ-9). Because even briefer measures might be desirable for use in busy clinical settings or as part of comprehensive health questionnaires, we evaluated a 2-item version of the PHQ depression module, the PHQ-2.
The PHQ-2 inquires about the frequency of depressed mood and anhedonia over the past 2 weeks, scoring each as 0 ("not at all") to 3 ("nearly every day"). The PHQ-2 was completed by 6000 patients in 8 primary care clinics and 7 obstetrics-gynecology clinics. Construct validity was assessed using the 20-item Short-Form General Health Survey, self-reported sick days and clinic visits, and symptom-related difficulty. Criterion validity was assessed against an independent structured mental health professional (MHP) interview in a sample of 580 patients.
As PHQ-2 depression severity increased from 0 to 6, there was a substantial decrease in functional status on all 6 SF-20 subscales. Also, symptom-related difficulty, sick days, and healthcare utilization increased. Using the MHP reinterview as the criterion standard, a PHQ-2 score>> or =3 had a sensitivity of 83% and a specificity of 92% for major depression. Likelihood ratio and receiver operator characteristic analysis identified a PHQ-2 score of 3 as the optimal cutpoint for screening purposes. Results were similar in the primary care and obstetrics-gynecology samples.
The construct and criterion validity of the PHQ-2 make it an attractive measure for depression screening.