Acute and longer-term outcomes using ketamine as a clinical treatment at the Yale psychiatric hospital

Introduction

Ketamine has emerged as a rapid-acting antidepressant, though controversy remains regarding whether sufficient data exist to justify its use outside of research protocols. In October 2014, our institution began providing ketamine as an off-label therapy for patients not able to participate in research protocols on a case-by-case basis. Here we describe our experience over 30 months providing ketamine as a clinical treatment to participants with severe and treatment-resistant mood disorders.

Method

Initially, patients were treated with a single- or double-infusion protocol (0.5mg/kg over 40 minutes intravenously). We later transitioned to a 4-infusion protocol over two weeks.

Results

Overall, 54 patients have received ketamine at our institution, with 518 total infusions performed. A subset of 44 patients with mood disorders initiated the four-infusion protocol, of which 45.5% responded and 27.3% remitted by the 4th infusion. A subsample (N=14) have received ketamine on a long-term basis, ranging from 12 to 45 total treatments, over a course of 14 to 126 weeks. We found no evidence of cognitive decline, increased proclivity to delusions, or emergence of symptoms consistent with cystitis in this subsample.

Conclusion

In general, ketamine infusions have been tolerated well. The response and remission rates in our clinical sample were lower than those observed in some research protocols. The small number of patients who have been treated on a maintenance schedule limits the conclusions that can be drawn regarding long-term safety of ketamine, however no long-term adverse effects have been observed in our sample.