Clinical Summary
Clinical Summary: Clinical Outcomes of Intravenous Ketamine Treatment for Depression in the VA Health System
Veterans with major depressive disorder often have chronic, highly treatment-resistant illness, substantial psychiatric comorbidity, and limited benefit from standard antidepressants. This study shows what intravenous ketamine looks like in routine VA care over months rather than weeks, including how often patients improve, how long treatment is continued, and how infusion schedules change in practice.
Design
we analyzed VA medical record data
N
215 patients
Population
patients who received IV ketamine for depression in VA in FY20
Duration
over the next 12 months
Key Findings
- At 6 weeks, the mean improvement in PHQ-9 scores was 4.6 (SD = 6.8, median = 3.0; n = 164); 47% achieved minimally clinically important difference, 26% achieved response, and 15% achieved remission.
- At 12 weeks, the mean improvement in PHQ-9 scores was 4.4 (SD = 6.5, median = 4.0; n = 169); 44% achieved minimally clinically important difference, 25% achieved response, and 12% achieved remission.
- At 26 weeks, the mean improvement in PHQ-9 scores was 4.7 (SD = 6.7, median = 4.0 n = 171); 50% achieved minimally clinically important difference, 28% achieved response, and 13% achieved remission.
- In bivariate regression, the only variable associated with change in PHQ-9 score at 6 weeks was number of infusions, with a β coefficient of 0.7 (P = .002), indicating that each additional infusion was associated with a mean 0.7-point greater improvement in the 6-week PHQ-9 score.
- Treatment was typically continued beyond an acute series: in the 12 months following their initial infusion, 96% received additional infusions, with a mean total of 18 treatments (SD = 13, median = 16), and the interval between infusions increased from a mean of 5 days during the month after the first infusion to 23–28 days during months 5 to 12.
Clinical Bottom Line
In routine VA care, repeated intravenous ketamine produced modest but durable symptom improvement for a subset of patients with highly treatment-resistant depression, with about one-fourth reaching response and most gains occurring within 6 weeks. Maintenance treatment commonly continued for months as infusion frequency tapered.
Practice Implications
- Set expectations that meaningful improvement often requires repeated treatment: among those who ever met criteria, mean time to minimally clinically important difference was 51 days and 9 infusions, and mean time to response was 56 days and 9 infusions.
- Use an initial higher-frequency phase when pursuing intravenous ketamine, because more infusions within 6 weeks were linked to greater PHQ-9 improvement (β coefficient of 0.7; P = .002).
- Discuss that remission is less common than partial improvement in this population, with remission rates of 15% at 6 weeks, 12% at 12 weeks, and 13% at 26 weeks.
- Consider intravenous ketamine for complex major depressive disorder presentations seen in VA practice, including substantial psychiatric comorbidity, because demographic and diagnostic characteristics were not related to 6-week PHQ-9 outcomes and 70% of patients had posttraumatic stress disorder.
