Clinical predictive factors and trajectories of suicidal remission over 6 weeks following intravenous ketamine for suicidal ideation

BACKGROUND

Ketamine is efficient for short-term reduction of suicidal ideas. Predictive factors and outcome trajectories are poorly characterized.

METHODS

Secondary analyses were conducted on the KETIS study (Abbar et al. BMJ 2022): 156 suicidal patients were randomized to two intravenous infusions of racemic ketamine (0.5 mg/kg) or placebo. Response or remission was assessed over six weeks based on the Beck Scale for Suicidal Ideation (SSI). We calculated i) predictive values of 12 baseline variables on remission ii) outcome courses, and iii) positive (PPV) and negative predictive values.

RESULTS

In multivariate analyses, bipolar disorder, lower patient-rated suicidal ideas, and higher physical pain were predictive of suicidal remission at day 3. No clinical factor predicted remission at week 6. Twenty and 24 different clinical courses were identified in early (day 3) and later (week 6) follow-up, respectively, including around 40 % sustained remission, 50 % fluctuating course and 10 % no response. Suicidal remissions at day 1 and day 3 were highly predictive of remissions at day 3 and week 6 (PPV = 96.8 and 92.6 %).

LIMITATIONS

SSI may not be adapted for rapid variations and repeated measures.

CONCLUSIONS

Clinical factors were poorly predictive of remission. Fluctuations in suicidal ideas were frequent, even after ketamine (although less than placebo), necessitating vigilance and multimodal care. Remission at day 1 after one infusion was highly predictive of future remission. The benefits of a second infusion will have to be tested.

Ketamine for the acute treatment of severe suicidal ideation: double blind, randomised placebo controlled trial

OBJECTIVE

To confirm the rapid onset anti-suicidal benefits of ketamine in the short term and at six weeks, overall and according to diagnostic group.

DESIGN

Prospective, double blind, superiority, randomised placebo controlled trial.

SETTING

Seven French teaching hospitals between 13 April 2015 and 12 March 2019.

ELIGIBILITY CRITERIA FOR PARTICIPANTS

Aged 18 or older with current suicidal ideation, admitted to hospital voluntarily. Exclusion criteria included a history of schizophrenia or other psychotic disorders, substance dependence, and contraindications for ketamine.

PARTICIPANTS

156 participants were recruited and randomised to placebo (n=83) or ketamine (n=73), stratified by centre and diagnosis: bipolar, depressive, or other disorders.

INTERVENTION

Two 40 minute intravenous infusions of ketamine (0.5 mg/kg) or placebo (saline) were administered at baseline and 24 hours, in addition to usual treatment.

MAIN OUTCOME MEASURES

The primary outcome was the rate of patients in full suicidal remission at day 3, according to the scale for suicidal ideation total score ≤3. Analyses were conducted on an intention-to-treat basis.

RESULTS

More participants receiving ketamine reached full remission of suicidal ideas at day 3 than those receiving placebo: 46 (63.0%) of 83 participants in the ketamine arm and 25 (31.6%) of 73 in the placebo arm (odds ratio 3.7 (95% confidence interval 1.9 to 7.3), P<0.001). This effect differed according to the diagnosis (treatment: P<0.001; interaction: P=0.02): bipolar (odds ratio 14.1 (95% confidence interval 3.0 to 92.2), P<0.001), depressive (1.3 (0.3 to 5.2), P=0.6), or other disorders (3.7 (0.9 to 17.3, P=0.07)). Side effects were limited. No manic or psychotic symptom was seen. Moreover, a mediating effect of mental pain was found. At week 6, remission in the ketamine arm remained high, although non-significantly versus placebo (69.5% v 56.3%; odds ratio 0.8 (95% confidence interval 0.3 to 2.5), P=0.7).

CONCLUSIONS

The findings indicate that ketamine is rapid, safe in the short term, and has persistent benefits for acute care in suicidal patients. Comorbid mental disorders appear to be important moderators. An analgesic effect on mental pain might explain the anti-suicidal effects of ketamine.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02299440.

Residual Viremia Is Linked to a Specific Immune Activation Profile in HIV-1-Infected Adults Under Efficient Antiretroviral Therapy

Chronic immune activation persists in persons living with HIV-1 even though they are aviremic under antiretroviral therapy, and fuels comorbidities. In previous studies, we have revealed that virologic responders present distinct profiles of immune activation, and that one of these profiles is related to microbial translocation. In the present work, we tested in 140 HIV-1-infected adults under efficient treatment for a mean duration of eight years whether low-level viremia might be another cause of immune activation. We observed that the frequency of viremia between 1 and 20 HIV-1 RNA copies/mL (39.5 ± 24.7% versus 21.1 ± 22.5%, p = 0.033) and transient viremia above 20 HIV-1 RNA copies/mL (15.1 ± 16.9% versus 3.3 ± 7.2%, p = 0.005) over the 2 last years was higher in patients with one profile of immune activation, Profile E, than in the other patients. Profile E, which is different from the profile related to microbial translocation with frequent CD38+ CD8+ T cells, is characterized by a high level of CD4+ T cell (cell surface expression of CD38), monocyte (plasma concentration of soluble CD14), and endothelium (plasma concentration of soluble Endothelial Protein C Receptor) activation, whereas the other profiles presented low CD4:CD8 ratio, elevated proportions of central memory CD8+ T cells or HLA-DR+ CD4+ T cells, respectively. Our data reinforce the hypothesis that various etiological factors shape the form of the immune activation in virologic responders, resulting in specific profiles. Given the type of immune activation of Profile E, a potential causal link between low-level viremia and atherosclerosis should be investigated.

Microbial Translocation Is Linked to a Specific Immune Activation Profile in HIV-1-Infected Adults With Suppressed Viremia

Persistent immune activation in virologically suppressed HIV-1 patients, which may be the consequence of various factors including microbial translocation, is a major cause of comorbidities. We have previously shown that different profiles of immune activation may be distinguished in virological responders. Here, we tested the hypothesis that a particular profile might be the consequence of microbial translocation. To this aim, we measured 64 soluble and cell surface markers of inflammation and CD4+ and CD8+ T-cell, B cell, monocyte, NK cell, and endothelial activation in 140 adults under efficient antiretroviral therapy, and classified patients and markers using a double hierarchical clustering analysis. We also measured the plasma levels of the microbial translocation markers bacterial DNA, lipopolysaccharide binding protein (LBP), intestinal-fatty acid binding protein, and soluble CD14. We identified five different immune activation profiles. Patients with an immune activation profile characterized by a high percentage of CD38+CD8+ T-cells and a high level of the endothelial activation marker soluble Thrombomodulin, presented with higher LBP mean (± SEM) concentrations (33.3 ± 1.7 vs. 28.7 ± 0.9 μg/mL, p = 0.025) than patients with other profiles. Our data are consistent with the hypothesis that the immune activation profiles we described are the result of different etiological factors. We propose a model, where particular causes of immune activation, as microbial translocation, drive particular immune activation profiles responsible for particular comorbidities.

Transmission of wireless neural signals through a 0.18 µm CMOS low-power amplifier

In the field of Brain Machine Interfaces (BMI) researchers still are not able to produce clinically viable solutions that meet the requirements of long-term operation without the use of wires or batteries. Another problem is neural compatibility with the electrode probes. One of the possible ways of approaching these problems is the use of semiconductor biocompatible materials (silicon carbide) combined with an integrated circuit designed to operate with low power consumption. This paper describes a low-power neural signal amplifier chip, named Cortex, fabricated using 0.18 μm CMOS process technology with all electronics integrated in an area of 0.40 mm(2). The chip has 4 channels, total power consumption of only 144 μW, and is impedance matched to silicon carbide biocompatible electrodes.