A rapid positive influence of S- ketamine on the anxiety of patients in palliative care: a retrospective pilot study

Background Patients in palliative care need rapid-acting pharmacological options for psychological distress. N-methyl-D-aspartate antagonist ketamine is known to have a fast onset of anti-depressant and anxiolytic action. Its S -enantiomer S- ketamine (or esketamine) is an analgesic used as a routine treatment for refractory pain as an intravenous infusion (0.25 mg/kg over 45 min). This study investigates whether S- ketamine pain therapy has a positive impact on psychological distress caused by anxiety and depression in palliative care. Methods Patient routine data from a palliative care unit of a tertiary care hospital were used in a retrospective analysis after positive ethics approval. Eight patients, who received analgesic S- ketamine treatment, were compared to a control group matched by gender and age. The main analysis was conducted using three-way mixed MANOVA followed by two-way mixed ANOVA. Target variables were the values for anxiety and depression in the state-trait anxiety-depression inventory STADI. The predictor variables were the time of measurement before (T1) and after (T2) S- ketamine application and group membership. Results Comparison of the S- ketamine group ( n = 8; 4 male, 4 female; average age 52 years) with the control group ( n = 8; 3 male, 5 female; average age 55 years) revealed a significant multivariate effect on anxiety and depression F (1, 14) = 4.78; p = 0.046; r = 0.50. The univariate comparisons showed a significant reduction of the anxiety scores from T1 to T2 in the S- ketamine group compared to the control group F (1, 14) = 10.14; p = 0.007; r = 0.65. With regard to depression, there was no significant reduction from T1 to T2 in the group comparison F (1, 14) = 1.60; p = 0.23; r = 0.32. No long-lasting effects on pain were found. Conclusions Our findings show that psychological distress of patients in palliative care may improve after a single administration of S- ketamine, which mainly alleviates anxiety in those patients. Limitations of this study arise from non-randomization, retrospective analysis and low sample size. Therefore, further prospective and ideally randomized studies are necessary.