Mental Health
Depression screening using the Patient Health Questionnaire (PHQ)-9: Discrepancies between the sum score and diagnostic algorithm approach and the role of physical functioning in a nationally representative sample of U.S. adults Debbie Huang* Emily Goldmann Debbie Huang Rasmika Kumar Daniel Hagen Emily Goldmann
Background: The PHQ-9 is a validated instrument commonly used to screen for depressive symptoms. PHQ-9 scoring approaches include a dichotomized sum score (range 0-27) using a cut point of 10 and a diagnostic algorithm that reflects diagnostic criteria for major depressive episode in the Diagnostic and Statistical Manual of Mental Disorders (DSM)-5. Because several PHQ-9 items are somatic in nature, discordance in screening results using these scoring approaches may be related to physical functioning.
Methods: We used data from the 2021-2023 National Health and Nutrition Examination Survey (NHANES) for adult participants who had a positive screen for depression using the sum score approach (PHQ-9≥10) to compare those who did vs. those who did not also meet criteria for depression using the diagnostic algorithm approach (endorsed at least 5 of 9 PHQ-9 symptoms at least more than half of the days in the past two weeks, with at least one symptom being depressed mood or anhedonia). Logistic regression models examined the association between having a positive screen using the diagnostic algorithm approach and reporting at least one physical functioning limitation from the Short Set on Functioning (WG-SS), controlling for demographic variables.
Results: Among the 773 participants with PHQ-9≥10 (14% of 5,273 adult NHANES participants), 42% also screened positive using the diagnostic algorithm approach. Adjusting for age, gender, race/ethnicity, education, and marital status, physical functioning impairment was not associated with screening positive for depression using the diagnostic algorithm (adj. OR=1.1; 95% CI: 0.6,1.9).
Conclusion: Impairment in physical functioning did not explain differences between screening results using the sum score vs. the diagnostic algorithm approach among U.S. adults. Investigators should carefully consider the implications of using either approach. Further research on the comparative utility of PHQ-9 scoring approaches is warranted.