Examining the psychometric properties of brief screening measures of depression and anxiety in chronic pain: the Patient Health Questionnaire 2-item and Generalized Anxiety Disorder 2-item

Objective: Individuals with chronic pain experience anxiety and depressive symptoms at rates higher than the general population. The Patient Health Questionnaire 2-item (PHQ-2) and Generalized Anxiety Disorder 2-item (GAD-2) are brief screening measures of depression and anxiety, respectively. These brief scales are well-suited for use in routine care due to their brevity and ease of administration, yet their psychometric properties have not been established in heterogeneous chronic pain samples when administered over the Internet. Materials and Methods: Using existing data from randomized controlled trials of an established Internet-delivered pain management program (n = 1333), we assessed the reliability, validity, diagnostic accuracy, and responsiveness to treatment change in the PHQ-2 and GAD-2, as well as the long-form counterparts. Exploratory analyses were conducted to obtain cutoff scores using those participants with diagnostic data (n = 62). Results: The PHQ-2 and GAD-2 demonstrated appropriate reliability (eg, Cronbach's α = 0.79–0.84), validity (eg, higher scores in individuals with a diagnosis; p < 0.001), and responsiveness to treatment change (eg, pre- to post-treatment scores, p < 0.001). The psychometric properties of the short forms compared well with the longer forms. Cutoff scores on the short forms were consistent with general population samples, while cutoff scores on the long forms were higher than previously observed using general population samples. All four scales favored specificity over sensitivity. Conclusions: The PHQ-2 and GAD-2 demonstrated acceptable psychometric properties in the current sample, as did the long forms. Based on our findings, the PHQ-2 and GAD-2 can be used as screening tools with chronic pain samples when administered over the Internet.