Body mass index, waist circumference, insulin, and leptin plasma levels differentiate between clozapine-responsive and clozapine-resistant schizophrenia

BACKGROUND

Between 25% and 50% of patients suffering from treatment-resistant schizophrenia fail to achieve a clinical response with clozapine. The rapid identification and treatment of this subgroup of patients represents a challenge for healthcare practice.

AIMS

To evaluate the relationship between metabolic alterations and the clinical response to clozapine.

METHODS

A multicenter, observational, case-control study was performed. Patients diagnosed with schizophrenia treated with clozapine were eligible (minimum dose 400 mg/d for at least 8 weeks and/or clozapine plasma levels ⩾ 350 µg/mL). According to the Positive and Negative Syndrome Scale (PANSS) total score, patients were classified as clozapine-responsive (CR) (<80 points) or clozapine non-responsive (CNR) (⩾80 points). Groups were compared based on demographic and treatment-related characteristics, together with body mass index (BMI), waist circumference, insulin, leptin, and C-reactive protein plasma levels. Plasma levels of clozapine and its main metabolite, nor-clozapine, were measured in all the participants. In addition, the potential relationship between PANSS scores and leptin or insulin plasma levels was assessed.

RESULTS

A total of 46 patients were included: 25 CR and 21 CNR. BMI and waist circumference, fasting insulin and leptin plasma levels were lower in the CNR group, while C-reactive protein was not different. Moreover, significant negative correlations were observed between PANSS positive and general psychopathology subscores, on one hand, and insulin and leptin plasma levels, on the other hand, as well as between PANSS negative subscores and leptin plasma levels.

CONCLUSIONS

Our results suggest that the lack of metabolic effect induced by clozapine is associated with the lack of clinical response.

Difference between treatment-resistant schizophrenia and clozapine-resistant schizophrenia

We read the impressive review article “Clozapine resistant schizophrenia: Newer avenues of management” with great enthusiasm and appreciation. The author believes that preventing clozapine resistance from developing may be the most effective treatment strategy for patients with clozapine-resistant schizophrenia (CRS), and optimizing clozapine treatment is a key component. Disentangling the differences between treatment-resistant schizophrenia and CRS is important for studies addressing treatment strategies for these difficult-to-treat populations.

A prospective multicenter assessor-blinded randomized controlled study to compare the efficacy of short versus long protocols of electroconvulsive therapy as an augmentation strategy to clozapine in patients with ultra-resistant schizophrenia (SURECT study)

Background

Although clozapine is the most effective antipsychotic drug for treatment-resistant schizophrenia, it leads to a poor or partial response in 40 to 70% of patients. Augmentation of clozapine with electroconvulsive therapy (ECT) is a highly effective and relatively safe treatment for these clozapine-resistant patients. However, parameters are not yet well specified, such as the optimal number of sessions, their frequency, and the relevance of maintenance ECT. Our objective is to compare the efficacy and tolerance between two protocols of combined ECT and clozapine treatment in patients with ultra-resistant schizophrenia (URS): a 6-month protocol (short protocol with 20 ECT sessions) and a 12-month protocol (long protocol with 40 ECT sessions).

Methods

Sixty-four patients with schizophrenia with persistent psychotic symptoms despite clozapine treatment will be enrolled in a prospective multicentric assessor-blinded randomized controlled trial. Patients will be randomly assigned to the short or the long protocol. The main outcome is the response rate assessed by the Positive and Negative Symptoms Scale (PANSS) 3 months after the end of the treatment in patients following the long protocol compared to those following the short protocol. The response was defined as a 30% reduction on the PANSS baseline. Clinical assessments (PANSS, BPRS, HAMD-21, YMRS, CGI, GAF, Modified Overt Aggression Scale (MOAS), and Subjective Scale to Investigate Cognition in Schizophrenia (SSTICS)) and plasma clozapine concentration will be performed at baseline and at 2, 4, 6, 9, 12, and 15 months. Neuropsychological measures (MMSE, RL/RI-16, Doors test, D2 Test of Attention, Copy of the Rey-Osterrieth complex figure) will be performed at baseline and at 6 and 15 months.

Discussion

The aims of this research are to optimize protocols of combined ECT with clozapine in patients with URS and to offer specific recommendations for these patients’ care.

Trial registration

ClinicalTrials.gov NCT03542903. Registered on May 31, 2018. Id RCB: 2017-A02657-46