Long-term maintenance therapy with ketamine infusions for treatment-resistant depression: a retrospective chart review
E. Peters, A. Al Hasani, K. Shukla, K. HalpapeIntroduction
Ketamine therapy for treatment-resistant depression has a well-established rapid antidepressant effect for acute symptom management. However, there is far less research on the efficacy of long-term maintenance therapy for relapse prevention.
Objectives
To examine the utility of long-term maintenance therapy with ketamine infusions delivered in a naturalistic treatment setting.
Methods
We conducted a retrospective chart review of data from 56 outpatients with treatment-resistant depression receiving intravenous ketamine therapy in Saskatchewan, Canada. Depressive symptoms were assessed before each treatment session with the 17-item Hamilton Depression Rating Scale (HAM-D). The lowest HAM-D score after 3-6 infusions marked the start of maintenance therapy. From this point forward, Kaplan-Meier survival curves were used to estimate the probability of relapse (i.e., HAM-D score increase ≥ 25%, for two consecutive visits) over the next 365 days.
Results
Patients received, on average, 14 maintenance infusions over 253 days. The average number of days between infusions, per patient, was 25.5 ( SD = 8.86). Average HAM-D scores at the start of maintenance ( M = 17.2, SD = 7.31) did not increase by the final session ( M = 16.5, SD = 8.81; t = -0.94, p = .35). After 365 days, the estimated relapse rate was 21-36% depending on the minimum HAM-D score required to define a relapse. The average time to the start of a relapse was approximately 6 months, but individual times ranged from 14 to 328 days.
Conclusions
Long-term maintenance therapy with intravenous ketamine can be continued for up to a year alongside conventional treatment. During this time, roughly a third of patients may experience a persistent depressive symptom exacerbation of unknown clinical significance. More research is needed to determine the nature of these symptom exacerbations.
Disclosure of Interest
None Declared