Delayed Initiation of Clozapine Continues to Be a Substantial Clinical Concern

What is the current scope of research assessing patients' and clinicians' perspectives on clozapine treatment? A comprehensive scoping review

OBJECTIVES

Clozapine is continuously underused. The existing systematic reviews addressing barriers to clozapine prescribing primarily focus on clinical staff's attitudes and perceived barriers to prescribing. However, a preliminary literature search revealed additional literature on the subject not previously included in systematic reviews, including literature on patient perspectives. A scoping review is warranted to map the scope of primary studies on patients' and/or clinicians' perspectives on clozapine treatment and to identify gaps in research.

DESIGN

A scoping review was designed and reported in accordance with established guidelines for scoping reviews.

DATA SOURCES

The electronic databases Cochrane Library, CINAHL, Web of Science, PsycINFO, MEDLINE, EMBASE, Google Scholar and two grey literature databases were searched. Furthermore, citation tracking of selected studies was undertaken.

ELIGIBILITY CRITERIA

We included primary, empirical studies reporting clinicians' and/or patients' perspectives on clozapine treatment. No limitation was set for the year of publication or type of primary study.

DATA EXTRACTION AND SYNTHESIS

Two researchers independently screened for studies, extracted the data and coded the content. Findings were summarised visually and narratively.

RESULTS

146 studies were included. Most studies reported on patients' or clinicians' perspectives on active clozapine treatment or on clinicians' perspectives on barriers to clozapine initiation in general. Three gaps in research were identified: (1) clozapine-eligible, yet clozapine-naïve, patients' attitudes towards clozapine commencement, (2) clinicians' reasons for clozapine withholding and perceived facilitators of clozapine treatment in specific patient-cases and (3) patient and clinician perspectives on clozapine discontinuation, continuation and rechallenge in specific patient cases.

CONCLUSIONS

Research on clozapine perspectives tends to repeat itself. Future studies addressing the identified gaps in evidence could provide the insights needed to optimise clozapine utilisation.

Optimization of Clozapine Treatment: Study of Variables Affecting Response in Uruguayan Patients With Schizophrenia

PURPOSE/BACKGROUND

Clozapine is the recommended drug for treatment-resistant schizophrenia. Drug response could be affected by numerous factors such as age, sex, body mass index, co-medication, consumption of xanthine-containing beverages, smoking, and genetic variants of the enzymes involved in clozapine metabolism (CYP1A2, CYP3A4, and, to a lesser extent, CYP2C19 and CYP2D6). This study evaluated genetic and nongenetic variables that may affect clozapine plasma concentrations in Uruguayan patients with schizophrenia.

METHODS/PROCEDURES

Demographic data including sex, age, ethnicity, body weight, smoking habit, concomitant medication, and xanthine consumption were collected through a data collection form. Clozapine and norclozapine concentrations were determined using an HPLC system equipped with a UV detector. Genetic variants were determined through next-generation sequencing using Illumina sequencing technology and a panel of DNA probes.

FINDINGS/RESULTS

Fifty patients were included in the study. After evaluation, only tobacco use and obesity had a significant impact on clozapine exposure (P < 0.05). The high prevalence of the genetic variant CYP1A2*1F may account for the significant impact that tobacco smoking has on clozapine concentrations. Some common adverse effects observed in this study depend on clozapine plasma concentrations, such as constipation and sialorrhea.

IMPLICATIONS/CONCLUSIONS

These types of studies provide the clinician with tools to optimize clozapine therapy, attempting to use the minimum effective dose and attenuating the burden of concentration-dependent adverse reactions.

Clozapine as a mood stabiliser for schizoaffective disorder: Effectiveness during a three-month follow-up

Clozapine has shown signs of effectiveness in treating symptoms of schizoaffective disorder, although little research has been carried out to specifically assess this question. The objective of this current work was to analyse the mood-stabilising effectiveness and tolerability of clozapine in patients with schizoaffective disorder. This was a prospective, longitudinal, and quasi-experimental trial with three months of follow-up in patients with refractory schizoaffective disorder (PANSS score exceeding 80). Clinical response was evaluated through monthly visits using the YMRS, MADRS, CDSS, CGI-S and UKU. Twenty-seven participants (63% men, 37% women) with a mean age of 32.56 years were included. Clozapine significantly reduced the symptoms of mania, as measured by the YMRS (pre-treatment: 16.19, post-treatment: 0.67; p < 0.01) as well as the symptoms of depression, quantified with the CDSS (pre-treatment: 6.11, post-treatment: 0.67; p < 0.01), MADRS (pre-treatment: 9.56, post-treatment: 1.07; p < 0.01), and CGI-S (pre-treatment: 4.74, post-treatment: 1.15; p < 0.01). The prescription of clozapine significantly reduced the average daily dose of neuroleptics, measured in mg of chlorpromazine (pre-treatment: 1253.55, post-treatment: 742.59; p < 0.01) and hypnosedatives, measured in mg of diazepam (pre-treatment: 33.88, post-treatment: 5.74; p < 0.05) required in these patients. Patient-perceived tolerability, measured with the UKU, also improved during follow-up (pre-treatment: 12.89, post-treatment: 8.14; p < 0.01). The efficacy of clozapine was significant for the affective symptoms of schizoaffective disorder, thereby improving patient tolerability and permitting reductions in the other medications the patients used.

Prevalence of treatment-resistant schizophrenia among people with early psychosis and its clinical and demographic correlates

OBJECTIVE

The prevalence of treatment-resistant schizophrenia (TRS) among people with first-episode schizophrenia (FES) has been sub-optimally researched in Australia and internationally. We evaluated the prevalence of TRS among a cohort of FES patients and compared their sociodemographic and clinical characteristics to those with FES who were treatment responsive.

METHODS

Over 2 years, we collated demographic, clinical and treatment-related data of all patients with ICD-10 (International Classification of Diseases, Tenth revision) diagnosis of schizophrenia who were active in October 2020 at four early psychosis intervention services (EPIS) in Western Australia. We used a modified version of Suzuki et al. criteria to diagnose TRS. The data were analysed utilising descriptive statistics, the Mann-Whitney U test, Student's t-test and the False-Discovery Rate method.

RESULTS

The prevalence of TRS among the 167 patients diagnosed with FES was 41.3%, and the rates did not differ significantly between the services (p = 0.955). Those in the TRS group were less independent (p = 0.011), had more prolonged unemployment (p = 0.014) and were more likely to be on disability pension (p = 0.011) compared to the treatment responsive group. Furthermore, they had greater severity of symptoms (p = 0.002), longer duration of psychiatric symptoms (p = 0.019), more hospitalisations (p = 0.002) and longer cumulative admission durations (p = 0.002).

CONCLUSIONS

Our study revealed that treatment resistance to antipsychotics is prevalent among people with FES managed at EPIS. Notably, it establishes an association between TRS and heightened clinical severity and psychosocial and treatment burden. These findings highlight the imperative for early detection of treatment resistance and timely and specialised interventions for this condition in mental health services.

Predicting treatment resistance in positive and negative symptom domains from first episode psychosis: Development of a clinical prediction model

BACKGROUND

Treatment resistance (TR) in schizophrenia may be defined by the persistence of positive and/or negative symptoms despite adequate treatment. Whilst previous investigations have focused on positive symptoms, negative symptoms are highly prevalent, impactful, and difficult to treat. In the current study we aimed to develop easily employable prediction models to predict TR in positive and negative symptom domains from first episode psychosis (FEP).

METHODS

Longitudinal cohort data from 1027 individuals with FEP was utilised. Using a robust definition of TR, n = 51 (4.97 %) participants were treatment resistant in the positive domain and n = 56 (5.46 %) treatment resistant in the negative domain 12 months after first presentation. 20 predictor variables, selected by existing evidence and availability in clinical practice, were entered into two LASSO regression models. We estimated the models using repeated nested cross-validation (NCV) and assessed performance using discrimination and calibration measures.

RESULTS

The prediction model for TR in the positive domain showed good discrimination (AUC = 0.72). Twelve predictor variables (male gender, cannabis use, age, positive symptom severity, depression and academic and social functioning) were retained by each outer fold of the NCV procedure, indicating importance in prediction of the outcome. However, our negative domain model failed to discriminate those with and without TR, with results only just over chance (AUC = 0.56).

CONCLUSIONS

Treatment resistance of positive symptoms can be accurately predicted from FEP using routinely collected baseline data, however prediction of negative domain-TR remains a challenge. Detailed negative symptom domains, clinical data, and biomarkers should be considered in future longitudinal studies.

Dysfunction of the NMDA Receptor in the Pathophysiology of Schizophrenia and/or the Pathomechanisms of Treatment-Resistant Schizophrenia

For several decades, the dopamine hypothesis contributed to the discovery of numerous typical and atypical antipsychotics and was the sole hypothesis for the pathophysiology of schizophrenia. However, neither typical nor atypical antipsychotics, other than clozapine, have been effective in addressing negative symptoms and cognitive impairments, which are indices for the prognostic and disability outcomes of schizophrenia. Following the development of atypical antipsychotics, the therapeutic targets for antipsychotics expanded beyond the blockade of dopamine D2 and serotonin 5-HT2A receptors to explore the partial agonism of the D2 receptor and the modulation of new targets, such as D3, 5-HT1A, 5-HT7, and metabotropic glutamate receptors. Despite these efforts, to date, psychiatry has not successfully developed antipsychotics with antipsychotic properties proven to be superior to those of clozapine. The glutamate hypothesis, another hypothesis regarding the pathophysiology/pathomechanism of schizophrenia, was proposed based on clinical findings that N-methyl-D-aspartate glutamate receptor (NMDAR) antagonists, such as phencyclidine and ketamine, induce schizophrenia-like psychotic episodes. Large-scale genome-wide association studies (GWASs) revealed that approximately 30% of the risk genes for schizophrenia (the total number was over one hundred) encode proteins associated with glutamatergic transmission. These findings supported the validation of the glutamate hypothesis, which was inspired by the clinical findings regarding NMDAR antagonists. Additionally, these clinical and genetic findings suggest that schizophrenia is possibly a syndrome with complicated pathomechanisms that are affected by multiple biological and genetic vulnerabilities. The glutamate hypothesis has been the most extensively investigated pathophysiology/pathomechanism hypothesis, other than the dopamine hypothesis. Studies have revealed the possibility that functional abnormalities of the NMDAR play important roles in the pathophysiology/pathomechanism of schizophrenia. However, no antipsychotics derived from the glutamatergic hypothesis have yet been approved for the treatment of schizophrenia or treatment-resistant schizophrenia. Considering the increasing evidence supporting the potential pro-cognitive effects of glutamatergic agents and the lack of sufficient medications to treat the cognitive impairments associated with schizophrenia, these previous setbacks cannot preclude research into potential novel glutamate modulators. Given this background, to emphasize the importance of the dysfunction of the NMDAR in the pathomechanism and/or pathophysiology of schizophrenia, this review introduces the increasing findings on the functional abnormalities in glutamatergic transmission associated with the NMDAR.

Elevated intrinsic cortical curvature in treatment-resistant schizophrenia: Evidence of structural deformation in functional connectivity areas and comparison with alternate indices of structure

BACKGROUND

Research suggests structural and connectivity abnormalities in patients with treatment-resistant schizophrenia (TRS) compared to first-line responders and healthy-controls. However, measures of these abnormalities are often influenced by external factors like nicotine and antipsychotics, limiting their clinical utility. Intrinsic-cortical-curvature (ICC) presents a millimetre-scale measure of brain gyrification, highly sensitive to schizophrenia differences, and associated with TRS-like traits in early stages of the disorder. Despite this evidence, ICC in TRS remains unexplored. This study investigates ICC as a marker for treatment resistance in TRS, alongside structural indices for comparison.

METHODS

We assessed ICC in anterior cingulate, dorsolateral prefrontal, temporal, and parietal cortices of 38 first-line responders, 30 clozapine-resistant TRS, 37 clozapine-responsive TRS, and 52 healthy-controls. For comparative purposes, Fold and Curvature indices were also analyzed.

RESULTS

Adjusting for age, sex, nicotine-use, and chlorpromazine equivalence, principal findings indicate ICC elevations in the left hemisphere dorsolateral prefrontal (p < 0.001, η2partial = 0.142) and temporal cortices (LH p = 0.007, η2partial = 0.060; RH p = 0.011, η2partial = 0.076) of both TRS groups, and left anterior cingulate cortex of clozapine-resistant TRS (p = 0.026, η2partial = 0.065), compared to healthy-controls. Elevations that correlated with reduced cognition (p = 0.001) and negative symptomology (p < 0.034) in clozapine-resistant TRS. Fold and Curvature indices only detected group differences in the right parietal cortex, showing interactions with age, sex, and nicotine use. ICC showed interactions with age.

CONCLUSION

ICC elevations were found among patients with TRS, and correlated with symptom severity. ICCs relative independence from sex, nicotine-use, and antipsychotics, may support ICC's potential as a viable marker for TRS, though age interactions should be considered.

Impact of patient-specific factors on clozapine metabolism in individuals with treatment-resistant schizophrenia or schizoaffective disorder

BACKGROUND

There is high inter-individual variability in clozapine metabolism due to genetic and non-genetic differences. Patient-specific factors such as smoking, inflammation indicated by elevated C-reactive protein (CRP), and certain concurrent medications have a significant influence on clozapine metabolism.

AIM

To assess which patient-specific factors best explain variability in clozapine metabolism estimated by clozapine concentration to dose (C/D) ratios.

METHODS

A retrospective cohort analysis using electronic medical data was conducted on 172 inpatients at the BC Psychosis Program. Patients with normal renal and liver function were included if they were on clozapine and had at least one steady-state plasma concentration. The degree of influence of each factor on the variability of clozapine metabolism in the entire cohort and subgroups stratified by fluvoxamine use was evaluated using multiple linear regression analysis of C/D ratios.

RESULTS

Model fit testing showed that the entire cohort model accounts for 52.7% of C/D ratio variability, while the no fluvoxamine and fluvoxamine models accounted for 40.8% and 43.8%. In the entire cohort (n = 172), fluvoxamine use explained the highest variance, and C/D ratios were higher by 30.6% on average. The second strongest predictor was elevated CRP > 10 mg/L, and C/D ratios were higher by 22.9% on average. Subsequently, obesity, nonsmoker status, and female sex explained a significant but modest proportion of variance. Among participants on fluvoxamine (n = 58), only fluvoxamine dose was associated with an increase, and for every 25 mg increase in dose, C/D ratios increased by 5% on average.

CONCLUSION

In a clinical population, this study replicated the relationship between reduced rate of clozapine metabolism and the use of fluvoxamine, elevated CRP, obesity, nonsmoking status, and female sex; and the magnitude of the effects were large enough to be clinically relevant.

Development of an individualized risk calculator of treatment resistance in patients with first-episode psychosis (TRipCal) using automated machine learning: a 12-year follow-up study with clozapine prescription as a proxy indicator

About 15-40% of patients with schizophrenia are treatment resistance (TR) and require clozapine. Identifying individuals who have higher risk of development of TR early in the course of illness is important to provide personalized intervention. A total of 1400 patients with FEP enrolled in the early intervention for psychosis service or receiving the standard psychiatric service between July 1, 1998, and June 30, 2003, for the first time were included. Clozapine prescriptions until June 2015, as a proxy of TR, were obtained. Premorbid information, baseline characteristics, and monthly clinical information were retrieved systematically from the electronic clinical management system (CMS). Training and testing samples were established with random subsampling. An automated machine learning (autoML) approach was used to optimize the ML algorithm and hyperparameters selection to establish four probabilistic classification models (baseline, 12-month, 24-month, and 36-month information) of TR development. This study found 191 FEP patients (13.7%) who had ever been prescribed clozapine over the follow-up periods. The ML pipelines identified with autoML had an area under the receiver operating characteristic curve ranging from 0.676 (baseline information) to 0.774 (36-month information) in predicting future TR. Features of baseline information, including schizophrenia diagnosis and age of onset, and longitudinal clinical information including symptoms variability, relapse, and use of antipsychotics and anticholinergic medications were important predictors and were included in the risk calculator. The risk calculator for future TR development in FEP patients (TRipCal) developed in this study could support the continuous development of data-driven clinical tools to assist personalized interventions to prevent or postpone TR development in the early course of illness and reduce delay in clozapine initiation.

Non-prescribing of clozapine for outpatients with schizophrenia in real-world settings: The clinicians' perspectives

Clozapine is the gold standard for treating treatment-resistant schizophrenia although continuously underutilized. Previous surveys of clinicians have found that some of the most frequently cited barriers to clozapine prescribing are related to the blood-monitoring requirements. However, these surveys tend to explore general perspectives and may not reflect the true impact of different barriers in real-world outpatient settings. This study aimed to explore this issue. First, by surveying the clinicians responsible for the treatment of 39 clozapine-eligible, yet clozapine-naive, outpatients with schizophrenia. Then, based on the survey results, explanatory interviews with the participating psychiatrists were conducted and analyzed thematically. The most frequently cited reason for non-prescribing of clozapine was the expected non-compliance with blood-monitoring requirements; however, overall stability and/or severe mental illness was chosen as the most important reason in most patient-cases. The qualitative analysis highlighted the combined impact of standard clinical practice, personal experiences, and organizational constraints on clozapine utility.

Deconstructing the genetic architecture of treatment-resistant schizophrenia in East Asian ancestry

BACKGROUND

Treatment-resistant schizophrenia (TRS) affects a substantial proportion of patients who do not respond adequately to antipsychotic medications, yet the underlying biological mechanism remains poorly understood. This study investigates the link between the genetic predisposition to schizophrenia and TRS.

METHODS

857 individuals diagnosed with schizophrenia were divided into TRS (n = 142) and non-TRS (n = 715) based on well-defined TRS criteria. Polygenic risk scores (PRS) were calculated using schizophrenia genome-wide association summary statistics from East-Asian and European ancestry populations. PRS was estimated using both P-value thresholding and Bayesian framework methods. Logistic regression analyses were performed to differentiate between TRS and non-TRS individuals.

RESULTS

The schizophrenia PRS derived from the East-Asian training dataset effectively distinguished between TRS and non-TRS individuals (R2 = 0.029, p = 4.86 ×10-5, pT = 0.1, OR = 1.52, 95% CI = 1.242-1.861), with higher PRS values observed in the TRS group. Similar PRS analysis was conducted based on the European ancestry GWAS summary statistics, but we found superior prediction based on the East-Asian ancestry discovery data.

CONCLUSION

This study reveals an association between common risk variants for schizophrenia and TRS status, suggesting that the genetic burden of schizophrenia may partly contribute to treatment resistance in individuals with schizophrenia. These findings propose the potential use of genetic risk factors for early TRS identification and timely access to clozapine. However, the ancestral background of the discovery sample is crucial for successfully implementing PRS in clinical settings.

A Novel Gliotransmitter, L-β-Aminoisobutyric Acid, Contributes to Pathophysiology of Clinical Efficacies and Adverse Reactions of Clozapine

Clozapine is listed as one of the most effective antipsychotics and has been approved for treating treatment-resistant schizophrenia (TRS); however, several type A and B adverse reactions, including weight gain, metabolic complications, cardiotoxicity, convulsions, and discontinuation syndromes, exist. The critical mechanisms of clinical efficacy for schizophrenia, TRS, and adverse reactions of clozapine have not been elucidated. Recently, the GABA isomer L-β-aminoisobutyric acid (L-BAIBA), a protective myokine in the peripheral organs, was identified as a candidate novel transmission modulator in the central nervous system (CNS). L-BAIBA activates adenosine monophosphate-activated protein kinase (AMPK) signalling in both the peripheral organs and CNS. Activated AMPK signalling in peripheral organs is an established major target for treating insulin-resistant diabetes, whereas activated AMPK signalling in the hypothalamus contributes to the pathophysiology of weight gain and metabolic disturbances. Clozapine increases L-BAIBA synthesis in the hypothalamus. In addition, the various functions of L-BAIBA in the CNS have recently been elucidated, including as an activator of GABA-B and group-III metabotropic glutamate (III-mGlu) receptors. Considering the expressions of GABA-B and III-mGlu receptors (localised in the presynaptic regions), the activation of GABA-B and III-mGlu receptors can explain the distinct therapeutic advantages of clozapine in schizophrenia or TRS associated with N-methyl-D-aspartate (NMDA) receptor disturbance compared with other atypical antipsychotics via the inhibition of the persistent tonic hyperactivation of thalamocortical glutamatergic transmission in the prefrontal cortex. L-BAIBA has also been identified as a gliotransmitter, and a detailed exploration of the function of L-BAIBA in tripartite synaptic transmission can further elucidate the pathophysiology of effectiveness for treating TRS and/or specific adverse reactions of clozapine.

Rates and Reasons for Clozapine Treatment Interruptions: Impact of the Frequency of Hematologic Monitoring and Cardiac Adverse Events

BACKGROUND

Differing rates and reasons for interruptions of clozapine treatment have been reported globally. This article evaluated the rates and reasons for clozapine therapy interruptions in Australia and explored the impact of the frequency of hematological monitoring on these parameters.

METHODS

Data of the patients who were newly commenced on clozapine at three metropolitan public mental health services in Western Australia over 11 years were retrospectively collated. The rate and reasons for clozapine therapy interruptions and their association with the frequency of hematological monitoring, age, sex, and treatment site were analyzed using parametric, nonparametric, and correlational analyses.

RESULTS

Of the 457 patients whose data were collected, 69.6% had an interruption of treatment with 41.2% of those occurring during the period of mandatory weekly hematological monitoring in the first 18 weeks. Nonadherence (57.4%) and adverse effects (28.8%) were the 2 main reasons for the treatment interruptions. Cardiac issues accounted for the majority of the interruptions (61.8%) due to specified adverse effects, and these occurred significantly more commonly within the first 18 weeks. Location, age, and sex did not predict the possibility of treatment interruptions.

CONCLUSIONS

The high rates of clozapine treatment interruption observed during the period of weekly monitoring point toward the need to address the burden of frequent hematological monitoring for patients. Disproportionately higher rates of interruption due to cardiac adverse effects observed in this study compared with research from non-Australian settings raise the possibility of geographical differences in the adverse effects leading to treatment discontinuation.

Low Dose Clozapine in Early Onset Resistant Schizophrenia: Case Report and Two Year Follow-up

Childhood-onset schizophrenia (COS) is considered a rare and severe form of schizophrenia, with onset before age 13 and only half of affected patients responding to nonclozapine antipsychotics.¹ These patients with resistant COS show favorable responses to clozapine, but with higher adverse effects than seen in adults. Some resistant cases respond at a lower dose with minimal adverse effects.² However, it is unclear which patients will respond to a low dose and how long one should wait before increasing the dose of clozapine. We report a patient with resistant COS who showed a favorable but delayed-onset response to low-dose clozapine.

Second to none: rationale, timing, and clinical management of clozapine use in schizophrenia

Despite its enduring relevance as the single most effective and important evidence-based treatment for schizophrenia, underutilization of clozapine remains considerable. To a substantial degree, this is attributable to a reluctance of psychiatrists to offer clozapine due to its relatively large side-effect burden and the complexity of its use. This underscores the necessity for continued education regarding both the vital nature and the intricacies of clozapine treatment. This narrative review summarizes all clinically relevant areas of evidence, which support clozapine's wide-ranging superior efficacy - for treatment-resistant schizophrenia (TRS) and beyond - and make its safe use eminently feasible. Converging evidence indicates that TRS constitutes a distinct albeit heterogeneous subgroup of schizophrenias primarily responsive to clozapine. Most importantly, the predominantly early onset of treatment resistance and the considerable decline in response rates associated with its delayed initiation make clozapine an essential treatment option throughout the course of illness, beginning with the first psychotic episode. To maximize patients' benefits, systematic early recognition efforts based on stringent use of TRS criteria, a timely offer of clozapine, thorough side-effect screening and management as well as consistent use of therapeutic drug monitoring and established augmentation strategies for suboptimal responders are crucial. To minimize permanent all-cause discontinuation, re-challenges after neutropenia or myocarditis should be considered. Owing to clozapine's unique efficacy, comorbid conditions including substance use and most somatic disorders should not dissuade but rather encourage clinicians to consider clozapine. Moreover, treatment decisions need to be informed by the late onset of clozapine's full effects, which for reduced suicidality and mortality rates may not even be readily apparent. Overall, the singular extent of its efficacy combined with the high level of patient satisfaction continues to distinguish clozapine from all other available antipsychotics.

Dopamine supersensitivity psychosis and delay of clozapine treatment in patients with treatment-resistant schizophrenia

Both the underutilization of clozapine and treatment resistance of patients to clozapine are serious problems worldwide. Identifying clinical markers predicting response to clozapine would help clinicians more effectively utilize clozapine treatment. The present study retrospectively assessed dopamine supersensitivity psychosis (DSP) in addition to other measures such as age at disease onset and delay of clozapine introduction for a total of 47 treatment-resistant schizophrenia (TRS) patients. The response to clozapine was judged with CGI-C at 1 and 2 years from clozapine introduction. Results revealed that the DSP group tended to have a longer delay between designation of TRS and introduction of clozapine and continued to have slightly more severe psychopathology after treatment with clozapine, showing only slight improvement. The logistic regression analysis showed that the age at disease onset was the only significant indicator, predicting responsiveness to clozapine: patients with an onset age <20 years had a significantly better response to clozapine than patients with an onset age ≥20 years. The present study suggests that DSP might be related to a longer delay in clozapine introduction and the persistence of refractory symptoms despite clozapine treatment, whereas early age of disease onset might be related to a better response to clozapine.

Patients' and primary carers' views on clozapine treatment for schizophrenia: A cross-sectional study in Qatar

Subjective views of clozapine treatment among patients with schizophrenia in the Middle East and North African MENA Region have not previously been assessed. Globally, few studies have assessed the views of carers to clozapine treatment. We conducted a cross-sectional survey, using a clinician administered structured interview, of patients with schizophrenia/schizoaffective disorder prescribed clozapine in Qatar, and their primary carers. Participants were asked to rate clozapine against prior their antipsychotic treatment in terms of specific benefits and side effects. Forty-two patients and 33 carers participated in the study. Of the patients, two thirds were male, approximately half were Qatari and the mean age was 33.9 years. Patients and carers rated clozapine as superior to prior antipsychotic treatment on all 7 potential benefits inquired about. The greatest perceived benefit was improved mood. Patients rated clozapine as less likely to cause extrapyramidal side effects but more likely to cause 18 other potential side effects compared to prior antipsychotic treatment, with the greatest difference being for nocturnal salivation, increased appetite, and constipation. Nearly half of patients (48 %) and two thirds of carers (64 %) stated that they would have preferred to start clozapine earlier in their illness. Sixty percent of patients and 37 % of carers regarded the information that they had received from health professionals on clozapine as inadequate. Less than half of patients and approximately-two thirds of carers had adequate knowledge of haematological monitoring for clozapine. Generally, there were significantly positive correlation between patients and carers regarding the overall side effects of clozapine treatment. Likewise, improvement in hearing voices paranoid thoughts correlated with improved quality of life. In summary, the results show that patients and carers appreciate the benefits of clozapine despite its side effects being problematic. The results support clozapine being offered earlier in treatment and services providing more information on clozapine to patients and carers.

Clozapine research from India: A systematic review

BACKGROUND

Although clozapine is much researched in western literature, a review on Indian research on clozapine published in 2010 reported limited data and need for further research in this area.

AIM

We aimed to conduct a systematic review of research on clozapine from India from 2010 to mid-2022 and also compare the same with research output before 2010.

METHODOLOGY

A systematic various search engines, i.e., PUBMED, Medknow, Hinari and Google Scholar was done using the key words clozapine and India. Published articles with clozapine in the title and having an author from India, published during 2010 to July 2022 were included.

RESULTS

Initial Internet and hand searches yielded 280 articles, out of which 126 articles were excluded due to various reasons and 154 articles, were included for the review. This included 84 case reports, 49 original articles, 11 review articles and 10 letters to the editor as comments. We found an increase in the number of publications during the period of 2010-2022 compared to 1997-2009 in all types of publications. Over the years a significant proportion of the articles focused on various side effects of clozapine, factors associated with response and non-response to clozapine and evaluation of outcomes other than efficacy/effectiveness. However, all the studies were limited to a single centre with no multicentric studies on clozapine.

CONCLUSION

Over the last 12 years or so, there is increase in the number of publications on clozapine. However, there is lack of multicentric studies.

Clozapine prescription trends in Brazil in the last decade

OBJECTIVE

Clozapine is a second-generation antipsychotic indicated for treatment-resistant schizophrenia. Studies in several countries have shown a low rate of clozapine use despite the fact that approximately 30% of schizophrenia cases are treatment-resistant. In Brazil, few studies have addressed the frequency and variety of antipsychotic use in individuals diagnosed with schizophrenia (ICD F20). The objective of this study was to measure the rates of clozapine use in this population in the last decade using Brazilian Ministry of Health data.

METHODS

Prescriptions made between 2010 and 2020 in all 26 states and the Federal District registered at the Outpatient Information System Database from the Brazilian Health System (SIASUS) were evaluated.

RESULTS

A total of 25,143,524 prescriptions were recorded in this period, with clozapine representing 8.86% of all antipsychotics. The most frequently prescribed antipsychotic for patients with schizophrenia was olanzapine (35.8%), followed by quetiapine (27.5%). From 2010 to 2020, the rate of clozapine prescriptions in Brazil increased from 7.2% to 10.9%.

CONCLUSIONS

Despite a slight increase in prescriptions in the last decade, clozapine is still underutilized in Brazil.

Pharmacogenomics of Clozapine-induced agranulocytosis: a systematic review and meta-analysis

Although clozapine is the most effective pharmacotherapy for treatment-resistant schizophrenia, it is under-utilized, and initiation is often delayed. One reason is the occurrence of a potentially fatal adverse reaction, clozapine-induced agranulocytosis (CIA). Identifying genetic variations contributing to CIA would help predict patient risk of developing CIA and personalize treatment. Here, we (1) review existing pharmacogenomic studies of CIA, and (2) conduct meta-analyses to identify targets for clinical implementation. A systematic literature search identified studies that included individuals receiving clozapine who developed CIA and controls who did not. Results showed that individuals carrying the HLA-DRB1*04:02 allele had nearly sixfold (95% CI 2.20–15.80, p_corrected = 0.03) higher odds of CIA with a negative predictive value of 99.3%. Previously unreplicated alleles, TNFb5, HLA-B*59:01, TNFb4, and TNFd3 showed significant associations with CIA after multiple-testing corrections. Our findings suggest that a predictive HLA-DRB1*04:02-based pharmacogenomic test may be promising for clinical implementation but requires further investigation.

Genome-wide association analyses of symptom severity among clozapine-treated patients with schizophrenia spectrum disorders

Clozapine is the most effective antipsychotic for patients with treatment-resistant schizophrenia. However, response is highly variable and possible genetic underpinnings of this variability remain unknown. Here, we performed polygenic risk score (PRS) analyses to estimate the amount of variance in symptom severity among clozapine-treated patients explained by PRSs (R2) and examined the association between symptom severity and genotype-predicted CYP1A2, CYP2D6, and CYP2C19 enzyme activity. Genome-wide association (GWA) analyses were performed to explore loci associated with symptom severity. A multicenter cohort of 804 patients (after quality control N = 684) with schizophrenia spectrum disorder treated with clozapine were cross-sectionally assessed using the Positive and Negative Syndrome Scale and/or the Clinical Global Impression-Severity (CGI-S) scale. GWA and PRS regression analyses were conducted. Genotype-predicted CYP1A2, CYP2D6, and CYP2C19 enzyme activities were calculated. Schizophrenia-PRS was most significantly and positively associated with low symptom severity (p = 1.03 × 10-3; R2 = 1.85). Cross-disorder-PRS was also positively associated with lower CGI-S score (p = 0.01; R2 = 0.81). Compared to the lowest tertile, patients in the highest schizophrenia-PRS tertile had 1.94 times (p = 6.84×10-4) increased probability of low symptom severity. Higher genotype-predicted CYP2C19 enzyme activity was independently associated with lower symptom severity (p = 8.44×10-3). While no locus surpassed the genome-wide significance threshold, rs1923778 within NFIB showed a suggestive association (p = 3.78×10-7) with symptom severity. We show that high schizophrenia-PRS and genotype-predicted CYP2C19 enzyme activity are independently associated with lower symptom severity among individuals treated with clozapine. Our findings open avenues for future pharmacogenomic projects investigating the potential of PRS and genotype-predicted CYP-activity in schizophrenia.

Demographic and clinical characteristics of patients who recommence clozapine following therapy interruptions

OBJECTIVE

The proportion of patients who recommence clozapine after cessation, the time taken to resume clozapine post-cessation, and distinguishing demographic and clinical characteristics of this group have been poorly researched. We evaluated these in the current study.

METHOD

We retrospectively extracted selected demographic and clinical variables and clozapine treatment interruption and recommencement data up to December 2018 of a cohort of 458 patients who first commenced clozapine between 2006 and 2016. The study was conducted at three Australian health services.

RESULTS

Of the 310 (69%) patients who had at least one interruption of clozapine treatment, 170 (54.8%) did not resume clozapine, and 140 (45.2%) recommenced it after the first interruption. More than half of those who recommenced did so within a month and 80% by 12 months. Cox regression analysis revealed that age was significantly associated with recommencement, with a 2% decrease in the likelihood of restarting after an interruption for each year later that clozapine was initially commenced (HR = 0.98 95%CI: 0.97, 0.997, p = 0.02). Those who ceased clozapine due to adverse effects were less likely to restart than those who ceased due to noncompliance (HR = 0.63 95%CI: 0.41, 0.97, p = 0.03). More time on clozapine prior to interruption increased the likelihood of restarting it, with each additional month on clozapine increasing this likelihood by 1% (HR = 1.01 95%CI: 1.01, 1.02, p < 0.001).

CONCLUSION

If the distinguishing demographic and clinical characteristics of the group identified in this study are corroborated through further research, this could further validate the need to identify treatment resistance and commence clozapine early in people with schizophrenia and provide appropriate interventions to those more at risk of permanent discontinuation of clozapine.

Neuropsychological differences between treatment-resistant and treatment-responsive schizophrenia: a meta-analysis

Antipsychotic treatment resistance affects up to a third of individuals with schizophrenia. Of those affected, 70-84% are reported to be treatment resistant from the outset. This raises the possibility that the neurobiological mechanisms of treatment resistance emerge before the onset of psychosis and have a neurodevelopmental origin. Neuropsychological investigations can offer important insights into the nature, origin and pathophysiology of treatment-resistant schizophrenia (TRS), but methodological limitations in a still emergent field of research have obscured the neuropsychological discriminability of TRS. We report on the first systematic review and meta-analysis to investigate neuropsychological differences between TRS patients and treatment-responsive controls across 17 published studies (1864 participants). Five meta-analyses were performed in relation to (1) executive function, (2) general cognitive function, (3) attention, working memory and processing speed, (4) verbal memory and learning, and (5) visual-spatial memory and learning. Small-to-moderate effect sizes emerged for all domains. Similarly to previous comparisons between unselected, drug-naïve and first-episode schizophrenia samples v. healthy controls in the literature, the largest effect size was observed in verbal memory and learning [dl = -0.53; 95% confidence interval (CI) -0.29 to -0.76; z = 4.42; p < 0.001]. A sub-analysis of language-related functions, extracted from across the primary domains, yielded a comparable effect size (dl = -0.53, 95% CI -0.82 to -0.23; z = 3.45; p < 0.001). Manipulating our sampling strategy to include or exclude samples selected for clozapine response did not affect the pattern of findings. Our findings are discussed in relation to possible aetiological contributions to TRS.

Medication Gaps and Antipsychotic Polypharmacy in Previously Hospitalized Schizophrenia Patients: An Electronic Cohort Study in Three Canadian Provinces

BACKGROUND

Real world evidence about antipsychotics focuses on rehospitalization. Modeling the time course of pharmacotherapy would show patients' adherence to medications and physicians' adherence to medication guidelines. We aimed to calculate the cumulative time spent in second generation antipsychotics (SGAs), gaps, antipsychotic polypharmacy, and clozapine in discharged schizophrenia patients.

METHODS

Hospitalization and pharmacy dispensing data from 2008-2018 in Manitoba, Saskatchewan, and British Columbia were linked and an electronic cohort (N = 2,997) was created (mean follow-up: 49 months, SD = 38). Cohort members were required to have a minimum of 6 weeks medicated with aripiprazole, olanzapine, paliperidone, quetiapine, risperidone, or ziprasidone.

RESULTS

The multistate model predicted that schizophrenia patients accumulated 44 months in SGA monotherapy, 4 months in polypharmacy, 11 months in medication gaps and 17 days in clozapine over a 5-year period. The majority of transitions were between SGA and medication gap. Accumulated time in medication gaps was seven times as much as in clozapine. Each 10% delay in SGA initiation post-discharge was associated with a 2, 1, and 6% higher risk for polypharmacy (95% CI: 1.01-1.02), gap (95% CI: 1.01-1.01), and clozapine (95% CI: 1.04-1.08), respectively.

INTERPRETATION

Schizophrenia patients accumulated more time unmedicated and in polypharmacy compared to clozapine. Either treatment guidelines for schizophrenia are not followed, or real-world challenges hamper their implementation.

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.

Clozapine Management in Schizophrenia Inpatients: A 5-Year Prospective Observational Study of Its Safety and Tolerability Profile

BACKGROUND

Clozapine is well known for its efficacy and clinical superiority compared to other antipsychotics in treatment-resistant schizophrenia (TRS). However, it is frequently underutilized worldwide because of its acute adverse events, as well as for its long-term cardiometabolic and hematological consequences.

OBJECTIVE

The aim of the study was to evaluate 5-year safety in chronic TRS inpatients with continuous clozapine use.

METHODS

Patients with TRS and clozapine treatment were evaluated for 5 years. All participants were assessed using the Brief Psychiatric Rating Scale (BPRS), Glasgow Antipsychotic Side-effect Scale for Clozapine (GASS-C), Social Performance Scale (PSP) and Short Portable Mental Status Questionnaire (SPMSQ). Clinical, cardiometabolic and hematological data were collected periodically. General linear models (GLM) repeated measures controlling for CLZ dose were utilized to determine differences in variables across the time.

RESULTS

Overall, 189 inpatients were screened for study participation. The final sample included twenty-one TRS patients (16 males, 76%) with an average age of 57.6 years, all with 5-year continuous use of clozapine (mean dose 266 mg/day). There was not a significant effect of time on BPRS (p=0.774), PSP (p=0.855) and SPMSQ (p=0.066); differences remained not significant after controlling for CLZ dose (p=0.585, p=0.467 and p=0.105, respectively). No changes were found in blood and clinical parameters except for red blood cell count, which decreased over time (p=0.024; η2= 0.952). Patients reported a significant BMI decrease (-8.98 kg, p=0.008) between baseline and 5 years last observation.

CONCLUSION

The findings show how the application of a structured dietary, clinical and therapeutic monitoring program in psychiatric care facilities could allow the safe and effective long-term cardiometabolic and hematological management of clozapine. The unique role that clozapine plays in the current treatment of patients with TRS requires greater clinical awareness. Although its acute and chronic side effects are notorious, its safety management is feasible and broadens its potential practical application.

A Chart Audit Study of Clozapine Utilization in Early Psychosis

PURPOSE

This study aimed to document the treatment trajectories and clozapine use in first-episode psychosis patients and to document the underlying reasons for using or not using clozapine in patients not achieving psychosis remission.

METHODS

We conducted a retrospective chart audit of patients aged 18 to 30 years having DSM-5 diagnoses of schizophrenia spectrum psychotic disorders treated in 3 Canadian early intervention programs for psychosis. The severity of the patient's illness (using the Clinical Global Impression Severity [CGI-S] scale) and remission of psychosis were rated before and after each antipsychotic trial.

RESULTS

One hundred and forty-seven patients were included in the study. There were 19.7% patients exposed to clozapine after an average of 2.4 antipsychotic trials and a mean delay of 470.8 days. There were 75.9% patients who improved their CGI-S score (mean improvement, 2.5) after the clozapine trial and 62.1% achieved a CGI-S score ≤3. Full remission of psychosis on clozapine was achieved in 69.0% of the patients. Clozapine was successfully used for some patients with a nonadherent profile in our sample (eg, personality disorder, substance use disorder). Although the mean duration of clozapine trials during the observation period was 688.6 days, no patient discontinued clozapine because of adherence issues.

CONCLUSIONS

Clozapine use in these early intervention programs were at a rate consistent to what is expected from the literature and allowed a majority of patients to achieve remission of psychosis and to experience a robust improvement of severity of illness.

A potential biomarker for treatment stratification in psychosis: evaluation of an [18F] FDOPA PET imaging approach

[¹⁸F]FDOPA PET imaging has shown dopaminergic function indexed as K_i^cer differs between antipsychotic treatment responders and non-responders. However, the theragnostic potential of this biomarker to identify non-responders has yet to be evaluated. In view of this, we aimed to evaluate this as a theragnostic test using linear and non-linear machine-learning (i.e., Bernoulli, support vector, random forest and Gaussian processes) analyses and to develop and evaluate a simplified approach, standardised uptake value ratio (SUVRc). Both [¹⁸F]FDOPA PET approaches had good test-rest reproducibility across striatal regions (K_i^cer ICC: 0.68-0.94, SUVRc ICC: 0.76-0.91). Both our linear and non-linear classification models showed good predictive power to distinguish responders from non-responders (receiver operating curve area under the curve for region-of-interest approach: K_i^cer = 0.80, SUVRc = 0.79; for voxel-wise approach using a linear support vector machine: 0.88) and similar sensitivity for identifying treatment non-responders with 100% specificity (K_i^cer: ~50%, SUVRc: 40-60%). Although the findings were replicated in two independent datasets, given the total sample size (n = 84) and single setting, they warrant testing in other samples and settings. Preliminary economic analysis of [¹⁸F]FDOPA PET to fast-track treatment-resistant patients with schizophrenia to clozapine indicated a potential healthcare cost saving of ~£3400 (equivalent to $4232 USD) per patient. These findings indicate [¹⁸F]FDOPA PET dopamine imaging has potential as biomarker to guide treatment choice.

Demographic and clinical variables associated with response to clozapine in schizophrenia: a systematic review and meta-analysis

Clozapine is the only licensed pharmacotherapy for treatment-resistant schizophrenia. However, response to clozapine is variable. Understanding the demographic and clinical features associated with response to clozapine may be useful for patient stratification for clinical trials or for identifying patients for earlier initiation of clozapine. We systematically reviewed the literature to investigate clinical and demographic factors associated with variation in clozapine response in treatment-resistant patients with schizophrenia spectrum disorders. Subsequently, we performed a random-effects meta-analysis to evaluate differences in duration of illness, age at clozapine initiation, age of illness onset, body weight and years of education between clozapine responders and non-responders. Thirty-one articles were eligible for qualitative review and 17 of these were quantitatively reviewed. Shorter duration of illness, later illness onset, younger age at clozapine initiation, fewer hospitalisations and fewer antipsychotic trials prior to clozapine initiation showed a trend to be significantly associated with a better response to clozapine. Meta-analysis of seven studies, totalling 313 subjects, found that clozapine responders had a significantly shorter duration of illness compared to clozapine non-responders [g = 0.31; 95% confidence interval (CI) 0.06-0.56; p = 0.01]. The results imply that a delay in clozapine treatment may result in a poorer response and that a focus on prompt treatment with clozapine is warranted.

Clozapine-related drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome: a systematic review

INTRODUCTION

The Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) syndrome is a severe, multiorganic, and potentially life-threatening drug-induced hypersensitivity reaction, linked to several common drugs, including antiepileptics, antibiotics, and several psychotropic drugs, including clozapine. Due to the importance of clozapine in the management of treatment-resistant schizophrenia, a systematic review and characterization of clozapine-related DRESS syndrome is long overdue.

AREAS COVERED

This systematic review was conducted following PRISMA guidelines. PubMed, Embase, PsychINFO, and the Cochrane Library databases were independently reviewed up to 1 November 2019 for articles reporting clozapine-related DRESS syndrome cases. The RegiSCAR score system was applied to systematically characterize the clinical presentations of selected studies.

EXPERT OPINION

Clozapine-related DRESS syndrome was reported in six patients from four articles. Five patients received polypharmacy. Skin rash and liver involvement with elevated liver enzymes were very common. No fatal cases were found. Treatment mainly included clozapine discontinuation and immunosuppression. The mismatch between incidences of DRESS with other responsible drugs, the common misdiagnosis of this syndrome, and the fact that an extensive literature search only identified six cases suggests that clozapine-related DRESS may be overlooked. It is, therefore, necessary to optimize diagnostic strategies to identify immune-related side effects of clozapine.

Glutamate metabolites in treatment resistant schizophrenia: A meta-analysis and systematic review of 1H-MRS studies

Nearly a third to half of schizophrenia patients are non-responsive to first-line antipsychotics and are labelled treatment resistant schizophrenia (TRS). Neurochemical abnormalities in TRS may not be dopaminergic but possibly glutamate (Glu) related. Studies that have examined glutamatergic abnormalities using proton magnetic resonance spectroscopy (¹H-MRS) in TRS, have showed inconsistent results. Hence, we conducted a meta-analysis of ¹H-MRS studies comparing levels of Glu-and its metabolites in the brains of TRS and non-treatment resistant schizophrenia (nTRS) patients. Four eligible studies were included in the analysis. Summary effect size for the group difference between TRS (n = 101, including Ultra-TRS) and nTRS (n = 61) in Glu-levels in the anterior cingulate cortex (ACC) as measured with Hedges's g was 0.21 (95% CI: -0.42 to 0.85; p = 0.5) suggesting absence of significant difference. However, on leave one out analysis, one iteration showed significant difference in Glu-levels between the groups (Hedges's g = 0.46; p = 0.02) with higher Glu-levels in TRS implying significant effect of a single study on the effect size. The higher ACC Glu-in TRS was not associated with symptom severity or antipsychotic administration, indicating a possible trait abnormality. The limited number of datasets comparing Glu-metabolites in other brain regions are narratively described. Our analysis is limited by the significant heterogeneity between studies. Further longitudinal, prospective studies are needed to confirm higher Glu-metabolite levels in ACC in TRS and explore this potential trait abnormality.

Clozapine use - has practice changed?

BACKGROUND

One-third of individuals with schizophrenia have treatment-resistant illness. Of these, up to 60% will respond to clozapine treatment.

AIMS

This study retrospectively examined clozapine prescribing patterns against National Institute for Health and Care Excellence (NICE) guidelines as treatment-resistant illness emerged in a first-episode psychosis cohort.

METHODS

A total of 339 individuals with a first-episode psychosis were included in the study. Clozapine prescribing patterns were compared against the NICE guidelines and the impact of clozapine use on one index of service utilisation (hospitalisation) was assessed.

RESULTS

A total of 32 individuals (9.4%) from the cohort were prescribed clozapine. The mean time to clozapine trial was 2.1 years (SD 1.95; range 0.17-6.25). The mean number of adequate trials of antipsychotic prior to starting clozapine was 2.74 (SD 1.13; range 1-5). Following clozapine initiation, mean hospital admissions per year reduced from 2.3 to 0.3 (p=0.00). Mean hospital days pre- and post-clozapine also reduced (147 vs. 53; p=0.00). In total, 18 patients discontinued clozapine use during follow-up - 5 temporarily and 13 permanently.

CONCLUSIONS

Patients are being prescribed clozapine earlier than previously demonstrated, though delays are still evident, and many patients discontinue treatment. More work needs to be undertaken to understand and address factors which lead to its discontinuation.

A symptom combination predicting treatment-resistant schizophrenia - A strategy for real-world clinical practice

Early identification of symptoms that can predict treatment-resistant schizophrenia (TRS) could help clinicians to avoid delays in clozapine therapy. This study aims to investigate symptom patterns that could predict TRS using a discovery/replication study design. First, we followed a cohort of inpatients with schizophrenia (n = 164) in which the most discriminative items at baseline of the Positive and Negative Syndrome Scale (PANSS) were determined using logistic regression with TRS status as an outcome. Using Receiver Operating Characteristic (ROC) curves, we tested the prediction performance of multiple combinations of the identified items. The same items' combination was tested in an independent replication sample of (n = 207) outpatients with schizophrenia. In the discovery sample, the best combination to predict TRS at the discharge was the sum of three baseline PANSS items - conceptual disorganization (P2), difficulty in abstract thinking (N5), and unusual thought content (G9). The P2 + N5 + G9 model yielded an area under the curve (AUC) of 0.881, a sensitivity of 77.8%, and a specificity of 83.3%. In the outpatient sample, the model P2 + N5 + G9 predictive accuracy for TRS was only in the range of "acceptable" with an AUC of 0.756 and sensitivity of 72.3% and a specificity of 74.4%. Overall, the P2 + N5 + G9 model corresponds to the construct of formal thought disorder composed of disorganized thinking, concrete thinking, and bizarre-idiosyncratic thinking. Pronounced levels of these symptoms are easily identifiable in clinical practice and may be a feasible strategy in TRS. Replicating in first-episode cohorts is desirable to understand the likely clinical utility.