Accurately Identifying Major Depression in Traumatic Brain Injury

What is the study about?

This study looked at how well two depression screening tools — the PHQ-2 and the PHQ-9 — can detect major depressive disorder (MDD) in people who have had a traumatic brain injury (TBI). Depression is a serious mental health condition that causes persistent sadness, loss of interest, and other problems that interfere with daily life. MDD is a clinical diagnosis of depression that meets specific criteria. PHQ‑2 has 2 questions on mood and interest; PHQ‑9 has 9 covering full depression symptoms. Both ask about symptoms in the past 2 weeks. The study looked at whether standard cutoff scores used by large health organizations are accurate for people with TBI or need adjustment for this group.

What did the study find?

The study found that the PHQ-2 works well as a first-step screening tool for depression in people with TBI, but the best cutoff score for people with TBI is different from what large health organizations currently use. The key findings were:

PHQ-2 used alone: A cutoff score of 2 works best for people with TBI, correctly identifying 86% of those with MDD and 83% of those without it. The higher cutoff of 3 or more (used by the VA and Medicare) only detects 73% of cases, so more people with depression are missed.

PHQ-2 and PHQ-9 used together (2-step approach): This worked better. First, anyone scoring 1 or higher on the PHQ‑2 completed the full PHQ‑9. A positive PHQ‑9 meant having 5 or more symptoms for several days or more. This two-step approach identified 93% of people with MDD and correctly ruled out 89% without it. 

Efficiency: Using this 2-step approach, only 53.6% of patients needed to complete the full 9-question PHQ-9, saving time for both patients and clinicians.
 

The standard approach (PHQ-2 score of 3 or more, then PHQ-9 score of 10 or more) identified only 70% of people with TBI who had MDD—missing nearly 1 in 3 cases. The TBI-specific approach identified 93%, a 23-point improvement.

Who participated in the study?

The study included 135 adults with mild to severe TBI from a Seattle trauma center. All were 18 or older, English-speaking, and had confirmed TBI based on imaging or a low score on the Glasgow Coma Scale (GCS). Participants were assessed about 4 months after injury. The average age was 42; most were male (71%) and white (90%). The main causes of TBI were motor vehicle crashes (47%) and falls (32%). Participants were assessed at multiple time points within the first year after their injury and were assessed on average 3.8 months post-TBI.

How was the study conducted?

Participants completed PHQ-9 interviews by phone at multiple points within a year after TBI; PHQ-2 scores were derived from the first two items from the PHQ-9. Within 7 days, trained nurse practitioners administered the Structured Clinical Interview for DSM-IV (SCID) in person or by phone, which served as the reference for correctly diagnosing MDD. Researchers assessed how accurately the PHQ-2 and PHQ-9 identified MDD, tested PHQ-2 reliability, and examined its correlation with other measures. Statistical methods accounted for oversampling of participants with higher depression scores.

How can people use the results?

TBI survivors and families: Depression affects about 1 in 4 people after moderate–severe TBI and is often missed. If you’re asked two questions about mood and interest, even answering “several days” to one may justify further evaluation—you don’t need a high score to get help. Knowing about these screening tools can help you have an informed conversation with your healthcare provider.

Clinicians (doctors, nurses, therapists, and rehabilitation teams): Using a lower cutoff of 1 or more on the PHQ-2, followed by a full PHQ-9 with a threshold of 5 or more symptoms endorsed at “several days,” produces much better results for this population. Clinicians working with TBI patients should consider adopting these TBI-specific thresholds in their practice.

Researchers: Larger, multi-site studies are needed to confirm these findings across more diverse TBI populations. Future research should also explore whether these optimized cutoff scores perform equally well across different TBI severity levels, age groups, and racial and ethnic groups.

Policy makers and health systems (VA, Medicare, CMS): The current depression screening thresholds used by the VA/DoD and Centers for Medicare and Medicaid Services (CMS) appear to underperform for people with TBI, potentially leaving a large proportion of this vulnerable population without a diagnosis or treatment. Updating guidelines to a TBI-specific 2-step PHQ-2/PHQ-9 approach could improve detection and reduce undertreatment.

Reference

Bombardier, C. H., Mistretta, E. G., Altschuler, R., Barber, J., & Fann, J. R. (2025). The accuracy of the PHQ-2 alone and combined with the PHQ-9 to identify major depression in traumatic brain injury. Journal of Head Trauma Rehabilitation, Advance online publication. https://doi.org/10.1097/HTR.0000000000001054

Disclaimer

The contents of this quick review were developed under a grant from the National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR grant number 90DPKT0009). NIDILRR is a Center within the Administration for Community Living (ACL), Department of Health and Human Services (HHS). The contents of this quick review do not necessarily represent the policy of NIDILRR, ACL, HHS, and you should not assume endorsement by the Federal Government.

The content of this Quick Review was generated and edited using Claude and Microsoft Co-Pilot and was carefully reviewed and edited by experts to ensure accuracy.