Clinical Outcomes of Intravenous Ketamine Treatment for Depression in the VA Health System.

ABSTRACT

Objective/Background: Intravenous (IV) ketamine is effective for reducing symptoms of major depressive disorder in short-term clinical trials; this study characterized clinical outcomes of repeated infusions in routine clinical practice and the frequency and number of infusions used to sustain symptom improvement.Methods: Records of IV ketamine infusions for depression and associated Patient Health Questionnaire-9 (PHQ-9) scores were identified from Veterans Health Administration (VA) electronic medical records for patients treated in Fiscal Year 2020 and up to 12 months following the date of their first infusion.Results: Sample patients (n = 215) had a mean baseline PHQ-9 score of 18.6 and a mean of 2.1 antidepressant medication trials in the past year and 6.1 antidepressant trials in the 20 years prior to their first ketamine infusion. Frequency of infusions decreased from every 5 days to every 3-4 weeks over the first 5 months of infusions, with a mean of 18 total infusions over 12 months. After 6 weeks of treatment, 26% had a 50% improvement in PHQ-9 score (response) and 15% had PHQ-9 score ≤ 5 (remission). These improvements were similar at 12 and 26 weeks. No demographic characteristics or comorbid diagnoses were associated with 6-week PHQ-9 scores.Conclusions: While only a minority of patients treated with IV ketamine for depression experienced response or remission, symptom improvements achieved within the first 6 weeks were sustained over at least 6 months with decreasing infusion frequency. Further study is needed to determine optimal infusion frequency and potential for adverse effects with repeated ketamine infusions for depression.