Objectives: The objective of this study was to assess the measurement properties of the self-reported Patient Health Questionnaire-9 (PHQ-9) and its 10-item observer version (PHQ-10OV) among nursing home residents.
Methods: We conducted a retrospective study of Minimum Data Set 3.0 assessments for national cohorts of Medicare Fee-for-Service beneficiaries who were newly admitted or incident long-stay residents in 2014-2015 at US nursing homes (NHs) certified by the Center for Medicare and Medicaid Services. Statistical analyses included examining internal reliability with McDonald's omega, structural validity with confirmatory factor analysis, and hypothesis testing for expected gender differences and criterion validity with descriptive statistics. The Chronic Condition Warehouse depression diagnoses were used as an administrative reference standard.
Results: Both the PHQ-9 and PHQ-10OV had good internal reliability with omega values above 0.85. The self-reported scale yielded good model fit for a one-factor solution, while the PHQ-10OV had slightly poorer fit and a lower standardized factor loading on the additional irritability item. Both scales appear sufficiently one-dimensional given that somatic items had higher factor loading on a general depression factor than on a somatic subfactor. We were unable to obtain expected gender differences on the PHQ-10OV scale. The PHQ-9 and PHQ-10OV were both highly specific but had poor sensitivity compared with an administrative reference standard.
Conclusions: The PHQ-9 appears to be a valid and promising measurement instrument for research about depression among NH residents, while the validity of the PHQ-10OV should be examined further with a structured psychiatric interview as a stronger criterion standard.
Keywords: depression; long-term care; measurement; psychometrics.
© 2019 John Wiley & Sons, Ltd.