Demographic and clinical features as predictors of clozapine response in patients with schizophrenia spectrum disorders: A systematic review and meta-analysis

Development and initial evaluation of a clinical prediction model for risk of treatment resistance in first-episode psychosis: Schizophrenia Prediction of Resistance to Treatment (SPIRIT)

BACKGROUND

A clinical tool to estimate the risk of treatment-resistant schizophrenia (TRS) in people with first-episode psychosis (FEP) would inform early detection of TRS and overcome the delay of up to 5 years in starting TRS medication.

AIMS

To develop and evaluate a model that could predict the risk of TRS in routine clinical practice.

METHOD

We used data from two UK-based FEP cohorts (GAP and AESOP-10) to develop and internally validate a prognostic model that supports identification of patients at high-risk of TRS soon after FEP diagnosis. Using sociodemographic and clinical predictors, a model for predicting risk of TRS was developed based on penalised logistic regression, with missing data handled using multiple imputation. Internal validation was undertaken via bootstrapping, obtaining optimism-adjusted estimates of the model's performance. Interviews and focus groups with clinicians were conducted to establish clinically relevant risk thresholds and understand the acceptability and perceived utility of the model.

RESULTS

We included seven factors in the prediction model that are predominantly assessed in clinical practice in patients with FEP. The model predicted treatment resistance among the 1081 patients with reasonable accuracy; the model's C-statistic was 0.727 (95% CI 0.723-0.732) prior to shrinkage and 0.687 after adjustment for optimism. Calibration was good (expected/observed ratio: 0.999; calibration-in-the-large: 0.000584) after adjustment for optimism.

CONCLUSIONS

We developed and internally validated a prediction model with reasonably good predictive metrics. Clinicians, patients and carers were involved in the development process. External validation of the tool is needed followed by co-design methodology to support implementation in early intervention services.

Identifying and managing treatment resistance early with the integration of a clozapine clinic within an early intervention for psychosis service

BACKGROUND

Despite being the most effective antipsychotic medication for treatment-resistant psychosis, clozapine is often under-utilized with long delays to initiation.

AIMS

This study aimed to determine whether the integration of a clozapine clinic within an early intervention for psychosis service resulted in a change in the rate and time to initiation of clozapine, the number of trials of different antipsychotic medications prior to clozapine, community initiation and discontinuation rates.

METHODS

A clozapine clinic was established in the Early Psychosis Prevention and Intervention Centre in Melbourne. This was a pre- and post-evaluation study design. The 'clozapine clinic' cohort included those who commenced on clozapine from 01 January 2016 to 30 June 2018.

RESULTS

Prior to the clozapine clinic, 24 young people commenced clozapine over the 30-month period compared to 36 in the clozapine clinic cohort (RR = 1.30, 95% CI: 0.75-2.28, p = .32). In the pre-clozapine clinic cohort, 4.6% of all those with a first episode of psychosis were commenced on clozapine compared to 6% in the clozapine clinic cohort. Prior to the clozapine clinic, the median time to the commencement of clozapine was 72 weeks (IQR: 38, 87), compared to 53.5 weeks (IQR: 38, 81.5) in the clozapine clinic (Z = -0.86, p = .393). The mean number of different antipsychotic medications prior to commencing clozapine remained stable at 3.2 (SD ± 1.1) in both cohorts (t = -0.20, p = .841). There was a lower rate of discontinuation in the clozapine clinic (43.5% vs. 14.7%, HR = 0.30, 95% CI: 0.09-0.98, p = .046).

CONCLUSIONS

While this study was underpowered and there are limitations to the naturalistic study design, the findings lend support to the integration of a clozapine clinic within early intervention for psychosis services.

Safety of BEN guidelines in clozapine treatment: A Canadian perspective

OBJECTIVE

Unidentified benign ethnic neutropenia (BEN) has been recognized as a factor contributing to clozapine underutilization and discontinuation. Guidelines were implemented to accommodate BEN in Canada, and our main objective was to evaluate clozapine's safety in a sample of Canadian psychiatric patients with BEN.

METHOD

A retrospective chart review was conducted at the Centre for Addiction and Mental Health, Toronto, Canada. Through the clozapine clinic registry, participants were identified who (i) received clozapine using the approved BEN guidelines for hematological monitoring, and (ii) had at least one complete blood count pre- and post-clozapine initiation.

RESULTS

Our sample population was comprised of 41 BEN patients who were African-Caribbean (49 %), African (34 %), African-North American (12 %), Middle Eastern (2 %), and Indian-Caribbean (2 %). There was a significant reduction in hematological alerts for these patients while monitored under BEN guidelines (p < 0.001). The mean within-patient ANC value was not significantly different one year after clozapine initiation compared to the pre-clozapine baseline (p = 0.069). None of the patients discontinued clozapine for hematological reasons.

CONCLUSIONS

Findings demonstrated that patients monitored under the modified hematological guidelines for BEN can be safely treated with clozapine. These findings have important clinical ramifications as increased implementation of BEN guidelines may allow for broader use of clozapine.

A systematic review of neuroimaging studies of clozapine-resistant schizophrenia

This systematic review aimed to review neuroimaging studies comparing clozapine-resistant schizophrenia patients with clozapine-responding patients, and with first-line antipsychotic responding (FLR) patients. A total of 19 studies including 6 longitudinal studies were identified. Imaging techniques comprised computerized tomography (CT, n = 3), structural magnetic resonance imaging (MRI, n = 7), magnetic resonance spectroscopy (MRS, n = 5), functional MRI (n = 1), single-photon emission computerized tomography (SPECT, n = 3) and diffusion tensor imaging (DTI, n = 1). The most consistent finding was hypo-frontality in the clozapine-resistant group compared with the clozapine-responding group with possible differences in frontal-striatal-basal ganglia circuitry as well as the GABA level between the two treatment-resistant groups. Additional statistically significant findings were reported when comparing clozapine-resistant patients with the FLR group, including lower cortical thickness and brain volume of multiple brain regions as well as lower Glx/Cr level in the dorsolateral prefrontal cortex. Both treatment-resistant groups were found to have extensive differences in neurobiological features in comparison with the FLR group. Overall results suggested treatment-resistant schizophrenia is likely to be a neurobiological distinct type of the illness. Clozapine-resistant and clozapine-responding schizophrenia are likely to have both shared and distinct neurobiological features. However, conclusions from existing studies are limited, and future multi-center collaborative studies are required with a consensus clinical definition of patient samples, multimodal imaging tools, and longitudinal study designs.

Effects of Early Clozapine Treatment on Remission Rates in Acute Schizophrenia (The EARLY Trial): Protocol of a Randomized-Controlled Multicentric Trial

BACKGROUND

Quick symptomatic remission after the onset of psychotic symptoms is critical in schizophrenia treatment, determining the subsequent disease course and recovery. In this context, only every second patient with acute schizophrenia achieves symptomatic remission within three months of initiating antipsychotic treatment. The potential indication extension of clozapine-the most effective antipsychotic-to be introduced at an earlier stage (before treatment-resistance) is supported by several lines of evidence, but respective clinical trials are lacking.

METHODS

Two hundred-twenty patients with acute non-treatment-resistant schizophrenia will be randomized in this double-blind, 8-week parallel-group multicentric trial to either clozapine or olanzapine. The primary endpoint is the number of patients in symptomatic remission at the end of week 8 according to international consensus criteria ('Andreasen criteria'). Secondary endpoints and other assessments comprise a comprehensive safety assessment (i. e., myocarditis screening), changes in psychopathology, global functioning, cognition, affective symptoms and quality of life, and patients' and relatives' views on treatment.

DISCUSSION

This multicentre trial aims to examine whether clozapine is more effective than a highly effective second-generation antipsychotics (SGAs), olanzapine, in acute schizophrenia patients who do not meet the criteria for treatment-naïve or treatment-resistant schizophrenia. Increasing the likelihood to achieve symptomatic remission in acute schizophrenia can improve the overall outcome, reduce disease-associated burden and potentially prevent mid- and long-term disease chronicity.

Developing prediction models for symptom severity around the time of discharge from a tertiary-care program for treatment-resistant psychosis

Antipsychotics are the only therapeutic class indicated in the symptomatic management of psychotic disorders. However, individuals diagnosed with schizophrenia or schizoaffective disorder may not always benefit from these first-line agents. This refractoriness to conventional treatment can be difficult to address in most clinical settings. Therefore, a referral to a tertiary-care program that is better able to deliver specialized care in excess of the needs of most individuals may be necessary. The average outcome following a period of treatment at these programs tends to be one of improvement. Nonetheless, accurate prognostication of individual-level responses may be useful in identifying those who are unlikely to improve despite receiving specialized care. Thus, the main objective of this study was to predict symptom severity around the time of discharge from the Refractory Psychosis Program in British Columbia, Canada using only clinicodemographic information and prescription drug data available at the time of admission. To this end, a different boosted beta regression model was trained to predict the total score on each of the five factors of the Positive and Negative Syndrome Scale (PANSS) using a data set composed of 320 hospital admissions. Internal validation of these prediction models was then accomplished by nested cross-validation. Insofar as it is possible to make comparisons of model performance across different outcomes, the correlation between predictions and observations tended to be higher for the negative and disorganized factors than the positive, excited, and depressed factors on internal validation. Past scores had the greatest effect on the prediction of future scores across all 5 factors. The results of this study serve as a proof of concept for the prediction of symptom severity using this specific approach.

Feasibility and Effect of Increasing Clozapine Plasma Levels in Long-Stay Patients With Treatment-Resistant Schizophrenia

BACKGROUND

It is unknown whether increasing the clozapine plasma level to 400, 750, or even 1000 ng/mL is a feasible and effective strategy in patients with treatment-resistant schizophrenia (TRS). We investigated this in long-stay patients with TRS.

METHODS

In long-stay TRS patients, doses of clozapine were increased gradually to reach target plasma levels of 400, 750, or 1000 ng/mL, depending on the clinical response and tolerability. After an effective or tolerated level was reached, positive and negative syndrome scale scores were evaluated after 3 months and 1 year.

RESULTS

Twenty-eight patients were included. Overall, 54% of the patients, and especially patients 60 years and older, could not achieve one of the clozapine target levels because of adverse effects. Three physically vulnerable patients died, probably not directly related to clozapine use. Although only 21% of patients achieved a more than 20% reduction in total symptoms at the 1-year follow-up, the mean severity of positive symptoms decreased from 18.18 to 15.10 ( P < 0.01). The largest decrease in positive symptoms was seen in TRS patients who achieved a plasma level of 750 ng/mL of clozapine.

CONCLUSIONS

Most TRS patients older than 60 years could not tolerate high clozapine levels and so this should not be attempted in older or otherwise physically vulnerable patients. Increasing clozapine levels to approximately 750 ng/mL in middle-aged patients with longstanding TRS may modestly reduce the severity of positive symptoms and improve the response rate.

Genomic Stratification of Clozapine Prescription Patterns Using Schizophrenia Polygenic Scores

BACKGROUND

Treatment-resistant schizophrenia affects approximately 30% of individuals with the disorder. Clozapine is the medication of choice in treatment-resistant schizophrenia, but optimizing administration and dose titration is complex. The identification of factors influencing clozapine prescription and response, including genetics, is of interest in a precision psychiatry framework.

METHODS

We used linear regression models accounting for demographic, pharmacological, and clinical covariates to determine whether a polygenic risk score (PRS) for schizophrenia would be associated with the highest dose recorded during clozapine treatment. Analyses were performed across 2 independent multiancestry samples of individuals from a UK patient monitoring system, CLOZUK2 (n = 3133) and CLOZUK3 (n = 909), and a European sample from a Norwegian therapeutic drug monitoring service (n = 417). In a secondary analysis merging both UK cohorts, logistic regression models were used to estimate the relationship between schizophrenia PRSs and clozapine doses classified as low, standard, or high.

RESULTS

After controlling for relevant covariates, the schizophrenia PRS was correlated with the highest clozapine dose on record for each individual across all samples: CLOZUK2 (β = 12.22, SE = 3.78, p = .001), CLOZUK3 (β = 12.73, SE = 5.99, p = .034), and the Norwegian cohort (β = 46.45, SE = 18.83, p = .014). In a secondary analysis, the schizophrenia PRS was associated with taking clozapine doses >600 mg/day (odds ratio = 1.279, p = .006).

CONCLUSIONS

The schizophrenia PRS was associated with the highest clozapine dose prescribed for an individual in records from 3 independent samples, suggesting that the genetic liability for schizophrenia might index factors associated with therapeutic decisions in cohorts of patients with treatment-resistant schizophrenia.

Two subtypes of schizophrenia identified by an individual-level atypical pattern of tensor-based morphometric measurement

Difficulties in parsing the multiaspect heterogeneity of schizophrenia (SCZ) based on current nosology highlight the need to subtype SCZ using objective biomarkers. Here, utilizing a large-scale multisite SCZ dataset, we identified and validated 2 neuroanatomical subtypes with individual-level abnormal patterns of the tensor-based morphometric measurement. Remarkably, compared with subtype 1, which showed moderate deficits of some subcortical nuclei and an enlarged striatum and cerebellum, subtype 2, which showed cerebellar atrophy and more severe subcortical nuclei atrophy, had a higher subscale score of negative symptoms, which is considered to be a core aspect of SCZ and is associated with functional outcome. Moreover, with the neuroimaging-clinic association analysis, we explored the detailed relationship between the heterogeneity of clinical symptoms and the heterogeneous abnormal neuroanatomical patterns with respect to the 2 subtypes. And the neuroimaging-transcription association analysis highlighted several potential heterogeneous biological factors that may underlie the subtypes. Our work provided an effective framework for investigating the heterogeneity of SCZ from multilevel aspects and may provide new insights for precision psychiatry.

Superior temporal gyrus functional connectivity predicts transcranial direct current stimulation response in Schizophrenia: A machine learning study

Transcranial direct current stimulation (tDCS) is a promising adjuvant treatment for persistent auditory verbal hallucinations (AVH) in Schizophrenia (SZ). Nonetheless, there is considerable inter-patient variability in the treatment response of AVH to tDCS in SZ. Machine-learned models have the potential to predict clinical response to tDCS in SZ. This study aims to examine the feasibility of identifying SZ patients with persistent AVH (SZ-AVH) who will respond to tDCS based on resting-state functional connectivity (rs-FC). Thirty-four SZ-AVH patients underwent resting-state functional MRI at baseline followed by add-on, twice-daily, 20-min sessions with tDCS (conventional/high-definition) for 5 days. A machine learning model was developed to identify tDCS treatment responders based on the rs-FC pattern, using the left superior temporal gyrus (LSTG) as the seed region. Functional connectivity between LSTG and brain regions involved in auditory and sensorimotor processing emerged as the important predictors of the tDCS treatment response. L1-regularized logistic regression model had an overall accuracy of 72.5% in classifying responders vs. non-responders. This model outperformed the state-of-the-art convolutional neural networks (CNN) model-both without (59.41%) and with pre-training (68.82%). It also outperformed the L1-logistic regression model trained with baseline demographic features and clinical scores of SZ patients. This study reports the first evidence that rs-fMRI-derived brain connectivity pattern can predict the clinical response of persistent AVH to add-on tDCS in SZ patients with 72.5% accuracy.

Factors Associated With Poor Response to Clozapine in Schizophrenia: A Study From Northern India

PURPOSE/BACKGROUND

Limited numbers of studies have assessed the predictors of clozapine nonresponse. This study aimed to assess the demographic and clinical factors associated with an inadequate response to clozapine in patients with treatment-resistant schizophrenia (TRS).

METHODS/PROCEDURES

Two hundred eighty-seven outpatients with TRS receiving clozapine for more than 1 year were divided into 2 groups based on the need for a second antipsychotic medication and/or electroconvulsive therapy after receiving clozapine in the maximum tolerable dose for at least 3 months.

RESULTS/FINDINGS

One hundred two patients (35.4%) were considered to be clozapine nonresponders. Compared with responders, clozapine nonresponders were more often unemployed at the time of starting clozapine (P = 0.04), had a longer duration of untreated psychosis (P = 0.007), had received significantly higher number of adequate antipsychotic trials in the past (P = 0.02), had received antipsychotic polypharmacy in the past (P = 0.01), had experienced adverse effects with first- (P < 0.001) and second-generation antipsychotics (P = 0.01), and had more medical comorbidities (P = 0.03). The nonresponders more frequently had visual hallucinations (P = 0.001), and feelings/acts or impulses attributed to some external source (P = 0.03) in the lifetime, and had a significantly higher Clinical Global Impression severity score at the time of starting of clozapine (P < 0.001). While on clozapine, nonresponders received significantly higher dose of clozapine (P = 0.001) and higher proportion of them experienced constipation (P = 0.04), hypersalivation (P = 0.002), and obsessive-compulsive symptoms (P = 0.05) as adverse effects of clozapine.

CONCLUSIONS/IMPLICATIONS

The present study shows that approximately one-third of patients with TRS do not respond to clozapine. However, clozapine nonresponders, although broadly similar in sociodemographic profile to clozapine responders, differ from clozapine responders on past treatment profile.

Using a statistical learning approach to identify sociodemographic and clinical predictors of response to clozapine

BACKGROUND

A proportion of people with treatment-resistant schizophrenia fail to show improvement on clozapine treatment. Knowledge of the sociodemographic and clinical factors predicting clozapine response may be useful in developing personalised approaches to treatment.

METHODS

This retrospective cohort study used data from the electronic health records of the South London and Maudsley (SLaM) hospital between 2007 and 2011. Using the Least Absolute Shrinkage and Selection Operator (LASSO) regression statistical learning approach, we examined 35 sociodemographic and clinical factors' predictive ability of response to clozapine at 3 months of treatment. Response was assessed by the level of change in the severity of the symptoms using the Clinical Global Impression (CGI) scale.

RESULTS

We identified 242 service-users with a treatment-resistant psychotic disorder who had their first trial of clozapine and continued the treatment for at least 3 months. The LASSO regression identified three predictors of response to clozapine: higher severity of illness at baseline, female gender and having a comorbid mood disorder. These factors are estimated to explain 18% of the variance in clozapine response. The model's optimism-corrected calibration slope was 1.37, suggesting that the model will underfit when applied to new data.

CONCLUSIONS

These findings suggest that women, people with a comorbid mood disorder and those who are most ill at baseline respond better to clozapine. However, the accuracy of the internally validated and recalibrated model was low. Therefore, future research should indicate whether a prediction model developed by including routinely collected data, in combination with biological information, presents adequate predictive ability to be applied in clinical settings.

Clinical predictors of response to clozapine in Tunisian patients with treatment resistant schizophrenia

INTRODUCTION

Treatment resistant schizophrenia (TRS), affecting approximately one-third of patients with schizophrenia, is associated with a serious impairment in global psychosocial functioning. Clozapine is the only licensed drug for TRS. However its prescription remains limited by its side effects requiring mandatory monitoring. The need to identify clinical factors associated with good response to clozapine in TRS has been established. The presence of ethnic differences in these factors and the scarcity of data on the Tunisian or more generally the North-African population warrants the conduct of a clinical study on the subject. The aim of this study was to investigate demographic, clinical, and biochemical patient characteristics as potential predictors of response to clozapine.

METHODS

This is a cross-sectional and retrospective study, at the "F and A psychiatry departments" of Razi Hospital in Manouba, Tunisia. All patients, with DSM 5 diagnosis of schizophrenia in its resistant form, on clozapine for at least 12 months and who consulted from June 1, 2018 to November 30, 2018 were included. We investigated premorbid functioning by the premorbid adjusment scale, demographic and clinical characteristics, and clozapine plasma level as potential clozapine response predictors. The response to clozapine was defined by a total BPRS score of 35 or less.

RESULTS

Sixty-three patients were included in the study. The mean age at clozapine introduction was 30,84 ±9,25 years. The mean duration of clozapine treatment was 7,22 ± 4,02 years. There were 16 clozapine responders (25%) who had BPRS total scores below or equal to 35 and 47 non-responders (75%). A higher premorbid social functioning in childhood (p = 0,018) and early adolescence (p = 0,024) was associated with better response to clozapine. A delay clozapine initiation shorter than 7 years(p = 0,036), one atypical antipsychotic trial (p = 0,029) and schizophrenia paranoid subtype (p< 0.01) were found to be significantly predictive of good clozapine response. None of the demographic factors or biochemical characteristics were associated with clozapine response.

CONCLUSIONS

Our work is consistent with previous studies suggesting the need for clinicians to be aware of the clinical predictors of a good response to clozapine to overcome their reluctance to prescribe it. It also highlighted the major prognostic role of premorbid adjustment in the clinical response to treatment. However, prospective studies including therapeutic drug monitoring would be very useful to better delineate the sub-group of patients to whom clozapine would benefit the most and to improve prescription modalities.

Clozapine induces metformin-resistant prediabetes/diabetes that is associated with poor clinical efficacy in patients with early treatment-resistant schizophrenia

BACKGROUND

Two distinct subtypes of treatment-resistant schizophrenia (TRS) have been recently reported, including early-treatment resistance (E-TR) and late-treatment resistance (L-TR). This study was to assess clozapine-induced metformin-resistant prediabetes/diabetes and its correlation with clinical efficacy in schizophrenia E-TR subtype.

METHODS

This prospective cohort study enrolled 230 patients with schizophrenia E-TR subtype and they were treated with adequate doses of clozapine for 16 weeks, during which patients with prediabetes/diabetes were assigned to receive add-on metformin. The main outcomes and measures included incidence of clozapine-induced prediabetes/diabetes and metformin-resistant prediabetes/diabetes, and the efficacy of clozapine as assessed by the Positive and Negative Syndrome Scale (PANSS) score.

RESULTS

Clozapine-induced prediabetes/diabetes occurred in 76.52% of patients (170 prediabetes and 6 diabetes), of which the blood sugar of 43 (24.43%) patients was controlled with metformin. Despite add-on metformin, 47.06% (74/170) of prediabetes patients progressed to diabetes. In total, the incidence of clozapine-induced metformin-resistant prediabetes/diabetes was 75.57% (133/176). On completion of 16-week clozapine treatment, 16.52% (38/230) patients showed clinical improvement with PANSS scores of ≥50% declining. Furthermore, clozapine-induced prediabetes/diabetes was significantly correlated with the poor clinical efficacy of clozapine for schizophrenia E-TR subtype.

CONCLUSIONS

The incidence of clozapine-induced metformin-resistant prediabetes/diabetes was considerably high in the schizophrenia E-TR subtype. Clozapine-induced metformin-resistant prediabetes/diabetes represents an independent risk factor that adversely affects the clinical efficacy of clozapine for the schizophrenia E-TR subtype. This study provided new evidence for re-evaluating the use of clozapine for TRS, especially E-TR subtype, and the use of metformin for the glycemic control of clozapine-induced prediabetes/diabetes.

Predictors of response to pharmacological treatments in treatment-resistant schizophrenia - A systematic review and meta-analysis

BACKGROUND

As the burden of treatment-resistant schizophrenia (TRS) on patients and society is high it is important to identify predictors of response to medications in TRS. The aim was to analyse whether baseline patient and study characteristics predict treatment response in TRS in drug trials.

METHODS

A comprehensive search strategy completed in PubMed, Cochrane and Web of Science helped identify relevant studies. The studies had to meet the following criteria: English language clinical trial of pharmacological treatment of TRS, clear definition of TRS and response, percentage of response reported, at least one baseline characteristic presented, and total sample size of at least 15. Meta-regression techniques served to explore whether baseline characteristics predict response to medication in TRS.

RESULTS

77 articles were included in the systematic review. The overall sample included 7546 patients, of which 41% achieved response. Higher positive symptom score at baseline predicted higher response percentage. None of the other baseline patient or study characteristics achieved statistical significance at predicting response. When analysed in groups divided by antipsychotic drugs, studies of clozapine and other atypical antipsychotics produced the highest response rate.

CONCLUSIONS

This meta-analytic review identified surprisingly few baseline characteristics that predicted treatment response. However, higher positive symptoms and the use of atypical antipsychotics - particularly clozapine -was associated with the greatest likelihood of response. The difficulty involved in the prediction of medication response in TRS necessitates careful monitoring and personalised medication management. There is a need for more investigations of the predictors of treatment response in TRS.

Efficacy and safety of clozapine in psychotic disorders-a systematic quantitative meta-review

A recent increase in the literature regarding the evidence base for clozapine has made it increasingly difficult for clinicians to judge "best evidence" for clozapine use. As such, we aimed at elucidating the state-of-the-art for clozapine with regard to efficacy, effectiveness, tolerability, and management of clozapine and clozapine-related adverse events in neuropsychiatric disorders. We conducted a systematic PRISMA-conforming quantitative meta-review of available meta-analytic evidence regarding clozapine use. Primary outcome effect sizes were extracted and transformed into relative risk ratios (RR) and standardized mean differences (SMD). The methodological quality of meta-analyses was assessed using the AMSTAR-2 checklist. Of the 112 meta-analyses included in our review, 61 (54.5%) had an overall high methodological quality according to AMSTAR-2. Clozapine appears to have superior effects on positive, negative, and overall symptoms and relapse rates in schizophrenia (treatment-resistant and non-treatment-resistant subpopulations) compared to first-generation antipsychotics (FGAs) and to pooled FGAs/second-generation antipsychotics (SGAs) in treatment-resistant schizophrenia (TRS). Despite an unfavorable metabolic and hematological adverse-event profile compared to other antipsychotics, hospitalization, mortality and all-cause discontinuation (ACD) rates of clozapine surprisingly show a pattern of superiority. Our meta-review outlines the superior overall efficacy of clozapine compared to FGAs and most other SGAs in schizophrenia and suggests beneficial efficacy outcomes in bipolar disorder and Parkinson's disease psychosis (PDP). More clinical studies and subsequent meta-analyses are needed beyond the application of clozapine in schizophrenia-spectrum disorders and future studies should be directed into multidimensional clozapine side-effect management to foster evidence and to inform future guidelines.

Investigating Predictors of Clozapine Response in Adolescents with Schizophrenia and Schizoaffective Disorder

Objectives: We aimed to determine the clinical predictors of clozapine response in patients with early-onset schizophrenia (EOS)/schizoaffective disorder and the effect of substance use disorder (SUD) on treatment outcomes. Methods: Medical records of patients with treatment-resistant EOS receiving clozapine were identified for data analysis dated between January 2015 and April 2020. Patients on clozapine were followed in an inpatient unit of a tertiary care mental health hospital. Using the Positive and Negative Symptom Scale (PANSS), ≥30% reduction was defined as the response criteria after clozapine treatment. Results: Of 50 subjects (age: 16.3 ± 1.3 years, 36.0% female), 22 subjects (44.0%) met the defined response criteria. Clozapine responder (CLZ-R) and clozapine nonresponder (CLZ-NR) groups were similar regarding age at illness onset, sex, and duration of untreated psychosis. The CLZ-R group had higher baseline positive PANSS scores (24.8 ± 8.1 vs. 17.1 ± 6.6, p = 0.001, d = 1.0) and total PANSS scores (94.8 ± 17.2 vs. 80.1 ± 19.8, p = 0.008, d = 0.8) compared with the CLZ-NR counterparts. The duration of hospital stay was longer in the CLZ-NR group (122.3 ± 48.2 vs. 87.3 ± 36.2 days, p = 0.007). Among 32 male patients, the presence of SUD (n = 9, 28.1%) was associated with a less reduction in total PANSS scores (F = 7.5, p = 0.010) and higher levels of positive symptoms at the end of the treatment (12.8 ± 4.1 vs. 18.8 ± 7.4, p = 0.006, d = 1.0). Synthetic cannabinoids were the most common substance type used among males with treatment-refractory EOS (25.0%). Conclusions: Our results did not support the role of sociodemographic variables in clozapine response. Positive symptoms and SUD yielded a prognostic value in patients receiving clozapine.

Predictors of clozapine discontinuation at 2 years in treatment-resistant schizophrenia

INTRODUCTION

Little is known about predictors of clinical response to clozapine treatment in treatment-resistant psychosis. Most published cohorts are small, providing inconsistent results. We aimed to identify baseline clinical predictors of future clinical response in patients who initiate clozapine treatment, mainly focusing on the effect of age, duration of illness, baseline clinical symptoms and homelessness.

METHODOLOGY

Retrospective cohort of patients with treatment-resistant schizophrenia, aged between 15 and 60 years, that initiated clozapine between 2014 and 2017. Sociodemographic characteristics, years from illness diagnosis, and clinical presentation before the initiation of clozapine were collected and analyzed. All-cause discontinuation at two years follow-up was used as the primary measure of clozapine response.

RESULTS

261 patients were included with a median age at illness diagnosis of 23 years old (IQR 19-29) and a median age at clozapine initiation of 25 (IQR: 21-33). 72.33% (183/253) continued clozapine after two years follow-up. Being homeless was associated to higher clozapine non-adherence, with an OR of 2.78 (95%CI 1.051-7.38) (p = 0.039, controlled by gender). Older age at clozapine initiation and longer delay from first schizophrenia diagnosis to clozapine initiation were also associated with higher clozapine non-adherence, with each year increasing the odds of discontinuation by 1.043 (95%CI 1.02-1.07; p = 0.001) and OR 1.092 (95%CI 1.01-1.18;p = 0.032) respectively.

CONCLUSION

Starting clozapine in younger patients or shortly after schizophrenia diagnosis were associated with better adherence.

Clozapine resistant schizophrenia: Newer avenues of management

About 40%-70% of the patients with treatment-resistant schizophrenia have a poor response to adequate treatment with clozapine. The impact of clozapine-resistant schizophrenia (CRS) is even greater than that of treatment resistance in terms of severe and persistent symptoms, relapses and hospitalizations, poorer quality of life, and healthcare costs. Such serious consequences often compel clinicians to try different augmentation strategies to enhance the inadequate clozapine response in CRS. Unfortunately, a large body of evidence has shown that antipsychotics, antidepressants, mood stabilizers, electroconvulsive therapy, and cognitive-behavioural therapy are mostly ineffective in augmenting clozapine response. When beneficial effects of augmentation have been found, they are usually small and of doubtful clinical significance or based on low-quality evidence. Therefore, newer treatment approaches that go beyond the evidence are needed. The options proposed include developing a clinical consensus about the augmentation strategies that are most likely to be effective and using them sequentially in patients with CRS. Secondly, newer approaches such as augmentation with long-acting antipsychotic injections or multi-component psychosocial interventions could be considered. Lastly, perhaps the most effective way to deal with CRS would be to optimize clozapine treatment, which might prevent clozapine resistance from developing. Personalized dosing, adequate treatment durations, management of side effects and non-adherence, collaboration with patients and caregivers, and addressing clinician barriers to clozapine use are the principal ways of ensuring optimal clozapine treatment. At present, these three options could the best way to manage CRS until research provides more firm directions about the effective options for augmenting clozapine response.

A Repeated Time-to-Positive Symptoms Improvement among Malaysian Patients with Schizophrenia Spectrum Disorders Treated with Clozapine

Clozapine remains the drug of choice for resistant schizophrenia. However, its dose-response relationship is still controversial. The current investigation aimed to develop a repeated time-to-positive symptoms improvement following the onset of clozapine treatment in Malaysian schizophrenia spectrum disorder patients. Data from patients’ medical records in the Psychiatric Clinic, Penang General Hospital, were retrospectively analyzed. Several parametric survival models were evaluated using nonlinear mixed-effect modeling software (NONMEM 7.3.0). Kaplan–Meier-visual predictive check (KM-VPC) and sampling-importance resampling (SIR) methods were used to validate the final model. A total of 116 patients were included in the study, with a mean follow-up of 306 weeks. Weibull hazard function best fitted the data. The hazard of positive symptoms improvement decreased 4% for every one-year increase in age over the median of 41 years (adjusted hazard ratio (aHR), 0.96; 95% confidence intervals (95% CI), (0.93–0.98)). However, patients receiving a second atypical antipsychotic agent had four-folds higher hazard (aHR, 4.01; 95% CI, (1.97–7.17)). The hazard increased 2% (aHR, 1.02; 95% CI, (1.01–1.03)) for every 1 g increase in the clozapine six months cumulative dose over the median of 34 g. The developed model provides essential information on the hazard of positive symptoms improvement after the first clozapine dose administration, including modifiable predictors of high clinical importance.

Clozapine: Why Is It So Uniquely Effective in the Treatment of a Range of Neuropsychiatric Disorders?

Clozapine is superior to other antipsychotics as a therapy for treatment-resistant schizophrenia and schizoaffective disorder with increased risk of suicidal behavior. This drug has also been used in the off-label treatment of bipolar disorder, major depressive disorder (MDD), and Parkinson's disease (PD). Although usually reserved for severe and treatment-refractory cases, it is interesting that electroconvulsive therapy (ECT) has also been used in the treatment of these psychiatric disorders, suggesting some common or related mechanisms. A literature review on the applications of clozapine and electroconvulsive therapy (ECT) to the disorders mentioned above was undertaken, and this narrative review was prepared. Although both treatments have multiple actions, evidence to date suggests that the ability to elicit epileptiform activity and alter EEG activity, to increase neuroplasticity and elevate brain levels of neurotrophic factors, to affect imbalances in the relationship between glutamate and γ-aminobutyric acid (GABA), and to reduce inflammation through effects on neuron-glia interactions are common underlying mechanisms of these two treatments. This evidence may explain why clozapine is effective in a range of neuropsychiatric disorders. Future increased investigations into epigenetic and connectomic changes produced by clozapine and ECT should provide valuable information about these two treatments and the disorders they are used to treat.

Prevalence and predictors of treatment-resistant schizophrenia in a tertiary hospital in Northeast Brazil

OBJECTIVE

To investigate epidemiological factors related to treatment-resistant schizophrenia (TRS) in Northeast Brazil, a region where data about mental health are still scarce.

METHODS

This retrospective cross-sectional study included all patients with schizophrenia currently receiving treatment at the outpatient psychiatric clinic of a tertiary hospital in Northeast Brazil. They were divided into TRS and treatment-responsive groups, and epidemiological characteristics of both groups were compared. A logistic regression model investigated factors related to treatment resistance.

RESULTS

Two hundred and five patients were included, 155 treatment-resistant and 50 treatment-responsive. The TRS group had higher use of benzodiazepines (36.1 vs. 18%, p = 0.017) and antiepileptics (36.8 vs. 8.0%, p < 0.001), antipsychotic polypharmacy (28.6 vs. 8%, p = 0.003) and suicide attempts (35.6 vs. 20%, p = 0.04). Age at onset was younger (19.7±7.3 vs. 24.6±8.6 years, p = 0.001) and CGI was higher in TRS (3.72±1.00 vs. 3.16±1.00, p = 0.001). In logistic regression, being married was a protector (odds ratio [OR] = 0.248, 95% confidence interval [95%CI] 0.091-0.679, p = 0.007) and younger age at onset was a predictor (OR = 1.076, 95%CI 1.034-1.120, p < 0.001) of treatment resistance.

CONCLUSION

Early onset of disease was associated with more treatment resistance, while being married with less resistance. Clinicians should identify early predictors of resistance in order to reduce unfavorable outcomes.

Clozapine Is Better Tolerated in Younger Patients: Risk Factors for Discontinuation from a Nationwide Database in Japan

OBJECTIVE

The effectiveness of clozapine is clearly superior to other antipsychotics in the treatment of refractory schizophrenia. Clozapine leads to various side effects, and therefore many patients are forced to discontinue. In this study, we analyzed the registry database of all cases in Japan to identify risk factors for discontinuation of clozapine.

METHODS

The Clozaril patient monitoring service® (CPMS) database from July 31, 2009 to January 26, 2020 was acquired. We defined the following exclusion criteria: patients who had ever taken clozapine by a non-CPMS method, such as an individual import or clinical trial, patients who did not receive clozapine after being enrolled in CPMS, and patients with initial doses other than 12.5 mg (outside the current protocol). Therefore, all patients in this study are new users. Multivariate Cox regression analysis was used to investigate independent risk factors associated with time to discontinuation of clozapine.

RESULTS

We identified 8,263 patients as the study population. Clozapine discontinuation was significantly associated with age 40 and older [hazard ratio (HR)=1.66, p<0.001], intolerance to olanzapine (HR=1.31, p=0.018), previous treatment with clozapine (HR=1.30, p=0.001), and leukocyte counts <6,000/mm3 (HR=1.24, p<0.001). The Kaplan-Meier curves for clozapine discontinuation by age group revealed that older age at the time of clozapine introduction tended to have lower continuation rates.

CONCLUSION

Careful administration is important because patients with these factors have a high risk of discontinuation. In addition, the initiation of clozapine during the younger period was more effective and more tolerated.

Possible pharmacogenetic factors in clozapine treatment failure: a case report

There is still much to learn about the predictors of therapeutic response in psychiatry, but progress is gradually being made and precision psychiatry is an exciting and emerging subspeciality in this field. This is critically important in the treatment of refractory psychotic disorders, where clozapine is the only evidence-based treatment but only about half the patients experience an adequate response. In this case report, we explore the possible biological mechanisms underlying treatment failure and discuss possible ways of improving clinical outcomes. Further work is required to fully understand why some patients fail to respond to the most effective treatment in refractory schizophrenia. Therapeutic drug monitoring together with early pharmacogenetic testing may offer a path for some patients with refractory psychotic symptoms unresponsive to clozapine treatment.

Predictors of Treatment-Resistant and Clozapine-Resistant Schizophrenia: A 12-Year Follow-up Study of First-Episode Schizophrenia-Spectrum Disorders

Studies on the long-term development and early predictors of treatment-resistant schizophrenia (TRS) and clozapine-resistant TRS (CR-TRS) in patients with first-episode schizophrenia-spectrum disorders (FES) are limited and have not considered the impact of early intervention services (EIS). This study aimed to explore the development of TRS and CR-TRS among patients with FES over 12 years of follow-up. Of the 1234 patients with FES, 15% developed TRS. A total of 450 patients with schizophrenia or schizoaffective disorder were included in a nested case-control study (157 TRS and 293 non-TRS). Younger age of onset, poorer premorbid social adjustment during adulthood, longer duration of first episode, a greater number of relapses, and a higher antipsychotic dose in the first 24 months were associated with earlier TRS. CR-TRS patients, constituting 25% of TRS patients, had a poorer premorbid social adjustment in late adolescence and longer delay before clozapine initiation compared with non-CR-TRS. CR-TRS had poorer clinical and functional outcomes at 12-year follow-up. However, TRS patients on clozapine had a lower mortality rate compared with non-TRS patients. EIS did not have a significant impact on the development of TRS, but patients in the EIS group had a shorter delay of clozapine initiation. Results suggested that neurodevelopmental factors, early clinical characteristics, and requirement for higher antipsychotic dose may be associated with TRS development, highlighting multiple pathways leading to this form of illness. Specific interventions including relapse prevention and early initiation of clozapine during the early course of illness may reduce the rate of TRS and improve patient outcomes.

Focus on Clozapine Withdrawal- and Misuse-Related Cases as Reported to the European Medicines Agency (EMA) Pharmacovigilance Database

BACKGROUND

Clozapine is of high clinical relevance for the management of both treatment-resistant schizophrenia and psychotic disturbances with concurrent drug misuse. Although the molecule presents with a range of well-known side-effects, its discontinuation/withdrawal syndrome has been only anecdotally described.

AIMS

the 2005-2018 European Medicines Agency (EMA) dataset of Adverse Drug Reactions (ADRs) was analyzed to identify and describe possible clozapine withdrawal- and misuse-/abuse-/dependence-related issues.

METHOD

A descriptive analysis of clozapine-related ADRs was performed when available, data on ADRs' outcome, dosage, and possible concomitant drug(s) were considered.

RESULTS

Out of 11,847 clozapine-related ADRs, some 599 (5.05%) were related to misuse/abuse/dependence/withdrawal issues, including 258 withdrawal-related (43.1%); 241 abuse-related (40.2%); and 80 intentional product misuse-related (13.3%) ADRs. A small number of overdose- and suicide-related ADRs were reported as well. Clozapine was typically (69.2%) identified alone, and most (84.7%) fatalities/high-dosage intake instances were reported in association with a history of substance abuse.

CONCLUSIONS

Previous suggestions about the possibility of a clozapine discontinuation/withdrawal occurrence are here supported, but further studies are needed. However, the misuse/abuse cases here identified might be difficult to interpret, given the lack of studies highlighting the possible recreational use of clozapine. The high-dosage intake, fatal outcomes and clozapine/polydrug abuse issues reported here may, however, be a reason for concern.

Clozapine Use in Patients with Early-Stage Schizophrenia in a Chinese Psychiatric Hospital

OBJECTIVE

Previous studies suggest that clozapine is commonly underutilized and that its initiation is delayed in patients with first-episode schizophrenia. Knowledge regarding clozapine use among Chinese patients with early-stage schizophrenia is limited. The aim of the present study was to investigate the point prevalence of and patterns and factors associated with clozapine use in patients with early-stage schizophrenia discharged from a psychiatric hospital in China.

METHODS

A retrospective study was conducted to analyze the prescriptions of 867 consecutive patients with early-stage schizophrenia who were admitted to the Affiliated Brain Hospital of Guangzhou Medical University between Jan 1, 2011 and Dec 31, 2016.

RESULTS

At discharge from the hospital, 114 (13.1%) patients were prescribed clozapine. Among the patients taking clozapine, 93 patients (81.6%) were prescribed clozapine polypharmacy, and only 21 patients (18.4%) were prescribed clozapine monotherapy. None of the patients were prescribed an overdose of clozapine. The mean daily dosage of clozapine was 160.97 mg, 149.05 mg and 213.69 mg among all patients taking clozapine, patients taking clozapine polypharmacy and patients taking clozapine monotherapy, respectively. The antipsychotic most frequently combined with clozapine was risperidone. Logistic regression suggested that the length of hospital stay, high school education, lower benzodiazepine use and antipsychotic polypharmacy were independently and significantly associated with clozapine use (P<0.05).

CONCLUSION

Although clozapine has been commonly used in China in recent years, the present study found that clozapine was not commonly used in patients with early-stage schizophrenia. An underutilization and delayed initiation of clozapine may exist in a portion of patients with early-stage schizophrenia. Given the unfavorable outcomes of underutilized and delayed clozapine use, future studies may be needed to assess and increase clozapine use in this population.