Assessing Depression in Primary Care with the PHQ‐9: Can It Be Carried Out over the Telephone?

Background: Telephone assessment of depression for research purposes is increasingly being used. The Patient Health Questionnaire 9‐item depression module (PHQ‐9) is a well‐validated, brief, self‐reported, diagnostic, and severity measure of depression designed for use in primary care (PC). To our knowledge, there are no available data regarding its validity when administered over the telephone. Objective: The aims of the present study were to evaluate agreement between self‐administered and telephone‐administered PHQ‐9, to investigate possible systematic bias, and to evaluate the internal consistency of the telephone‐administered PHQ‐9. Methods: Three hundred and forty‐six participants from two PC centers were assessed twice with the PHQ‐9. Participants were divided into 4 groups according to administration procedure order and administration procedure of the PHQ‐9: Self‐administered/Telephone‐administered; Telephone‐administered/Self‐administered; Telephone‐administered/Telephone‐administered; and Self‐administered/Self‐administered. The first 2 groups served for analyzing the procedural validity of telephone‐administered PHQ‐9. The last 2 allowed a test–retest reliability analysis of both self‐ and telephone‐administered PHQ‐9. Intraclass correlation coefficient (ICC) and weighted κ (for each item) were calculated as measures of concordance. Additionally, Pearson's correlation coefficient, Student's t ‐test, and Cronbach's α were analyzed. Results: Intraclass correlation coefficient and weighted κ between both administration procedures were excellent, revealing a strong concordance between telephone‐ and self‐administered PHQ‐9. A small and clinically nonsignificant tendency was observed toward lower scores for the telephone‐administered PHQ‐9. The internal consistency of the telephone‐administered PHQ‐9 was high and close to the self‐administered one. Conclusions: Telephone and in‐person assessments by means of the PHQ‐9 yield similar results. Thus, telephone administration of the PHQ‐9 seems to be a reliable procedure for assessing depression in PC.