Major Depressive Disorder: Tracking Treatment Trajectories in Veterans
—With a specific focus on U.S. veterans who received a diagnosis of depression after 9/11, a team of researchers recently examined the clinical characteristics and healthcare utilization patterns of those with moderate-to-severe major depressive disorder.
The investigators behind a new study examining the heterogeneity of course trajectories of moderate-to-severe major depressive disorder (MDD) in U.S. military veterans cited previous findings from epidemiologic studies demonstrating that, in most adults, depression is considered to be episodic in nature. The long-term trajectory of depression, they added, has been shown to be quite variable.1
Although most knowledge on depression trajectories has been derived from analyses conducted in civilian populations, depression is known to be widespread among veterans. In fact, when civilian and Veterans Affairs (VA) patient populations are compared, the utilization of health services and loss of productivity associated with MDD is higher among veterans.2
How the study was conducted
The research team behind the current study sought to assess the heterogeneity in 10-year trajectories associated with moderate-to-severe MDD in a group of U.S. veterans.1 The investigators explored MDD-linked service utilization, including mental healthcare history and related clinical characteristics, in veterans who were involved in military operations after September 11, 2001, and received an initial diagnosis of depression after this time.
“To our knowledge, our study is the first to evaluate trajectories of depression diagnoses over a 10-year period within the context of health service utilization among Veterans using medical record data,” the authors noted.1
Information was obtained from the Corporate Data Warehouse (CDW) of the Veterans Health Administration (VHA). Study inclusion criteria were as follows:
- Served in Operation Enduring Freedom and Operation Iraqi Freedom (OEF/OIF) and received VA care between 2001 and 2021 (the study period)
- Received at least 1 diagnosis of depression
- Experienced 1 or more positive depression screen on the Patient Health Questionnaire (PHQ) at any time during the study period
Electronic medical records were collected from a total of 293,265 veterans who served in OEF/OIF, in order to identify those who were diagnosed with MDD during the study period. Eligible participants needed to have a full year of prior clinical data available, along with health-related information associated with VHA services obtained for ≥10 years following their first depression diagnosis.
Patients are assigned to 1 of 4 depression trajectories
Latent class growth analysis (LCGA) was utilized to create group trajectories and to identify distinct groups of patients who have similar trajectories, with each patient assigned a probability of having membership in a particular group. “The response variable for the LCGA models was a past-year contact within the VA system with an MDD diagnosis,” the authors explained.1
A total of 25,307 patients—or roughly 1 in 12 who served in OEF/OIF—fulfilled eligibility criteria. Of these individuals, 25,252 had no missing values in the variables of interest and were enrolled in the study. Overall, 84% (21,280) of the patients were male, and nearly 70% (17,630) were White. The mean participant age at initial recorded MDD diagnosis was 34.1 (±9.25) years.
At baseline, 35.7% (9021) of the patients were diagnosed with posttraumatic stress disorder (PTSD), 3.4% (848) were not receiving VA benefits, 3.0% (747) had a history of combination treatment with psychotherapy plus medication prior to their initial depression diagnosis, and 1.9% (474) were diagnosed with severe MDD at their initial episode.
Based on LCGA, a comparison was conducted of demographics and clinical characteristics linked to the following 4 depression trajectories reported in the study population:
- Brief contact at the VA with a diagnosis of MDD: 29.8% (7536) of participants
- Later reentry into the VA system with a diagnosis of MDD: 40.2% (10,142) of participants
- Persistent contact with a probable diagnosis of MDD (defined as >60% of the time): 17.7% (4481) of participants
- Prolonged initial contact at a VA facility with a diagnosis of MDD (defined as 81% likelihood of contact in the first year, which declined to 20% by year 8 and rose to 33% by year 10): 12.2% (3093) of participants
Putting the findings into context
The results of the study revealed that, compared with veterans who had trajectories indicative of brief contact with the VA system regarding an MDD diagnosis, those participants who underwent protracted therapy (individuals in the persistent contact group or the prolonged initial contact group) were more likely to be diagnosed with PTSD, or with moderate-to-severe or recurrent MDD.
These findings should be interpreted with some caution, however. The trajectories used are based entirely on the presence of a diagnosis within patients’ medical charts and provider-rated disease severity, without the use of any patient-reported symptom severity measures, including the PHQ-9, which was never administered systematically during the study period.
“Among our Veterans, female, minority, and Veterans receiving VA benefits for military-associated disabilities were more likely to engage with care for depression persistently,” the authors emphasized. “Healthcare systems should prioritize further understanding [of] both reasons for return to care and drop out of care or refraining from returning to mental healthcare.”1
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