In Reply Individuals who screen positive for depression but fall below the formal diagnostic threshold often have clinically significant depression. According to the assumptions by Dr Nurnberg, the positive predictive value of the Patient Health Questionnaire-2 (PHQ-2) in the general population is 5%. However, a primary care study reported that the PHQ-2 has a positive predictive value of 38.6% for major depressive disorder and 74.9% for any depressive disorder.1 The absence of expert assessments of depression in the Medical Expenditure Panel Surveys prevent firm conclusions concerning the operating characteristics of the PHQ-2 in the general population. Even after allowing for the dependence of the positive predictive value on prevalence, however, we view the PHQ-2 as a reasonable brief indicator of clinically significant depression.
Olfson M, Blanco C, Marcus SC. Screening for Depression Through a Glass Darkly—Reply. JAMA Intern Med. 2017;177(3):447-448. doi:10.1001/jamainternmed.2016.9287