Measurement stability and differential domain-specific trajectories of the PHQ-9 in late-life depression: Evidence from a collaborative care trial.
J Affect DisordJun 27, 2026 (epub)
Rebecca Ndukwe, Marcia Scazufca, Pepijn Van de Ven
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In 30 seconds
This randomized controlled trial analyzed the stability of the two-factor structure of the PHQ-9 in older adults (N=558) with moderate-to-severe depression. Results indicated metric invariance across three assessments, with the intervention leading to a steeper improvement in cognitive-affective symptoms, while somatic symptoms showed no significant change.
Key findings
- Metric invariance of the PHQ-9 structure was supported across three assessment points.
- The intervention resulted in a steeper improvement in cognitive-affective symptoms.
- No significant effect was observed on somatic symptom trajectories.
- Within-person somatic deviations were temporally associated with cognitive-affective deviations.
Why it matters
Understanding the stability of the PHQ-9's structure and its domain-specific trajectories can enhance monitoring and treatment strategies for late-life depression, particularly in collaborative care settings.