Discontinuation of clozapine: a 15-year naturalistic retrospective study of 320 patients

Comparison of the Effectiveness and Safety of Clozapine Between Once-Daily and Divided Dosing Regimen in Patients With Treatment-Resistant Schizophrenia

BACKGROUND

Clozapine is the most effective antipsychotic with respect to the incidence of discontinuation and is indicated for treatment-resistant schizophrenia. Although the recommendation for clozapine administration is divided dosing, once-daily dosing of clozapine is commonly prescribed in many countries. However, there is currently no clinical data comparing all-cause discontinuation between the 2 methods of administration of clozapine.

OBJECTIVES

To compare the all-cause discontinuation and safety of clozapine administration between once-daily and divided dosing regimens.

METHODS

This was a retrospective cohort study. Participants were patients with treatment-resistant schizophrenia who had received 300 to 600 mg/day of clozapine for at least 3 months. Data were collected from outpatient medical records at Somdet Chaopraya Institute of Psychiatry. Eligible patients were classified into 2 groups: once-daily dosing and divided dosing. The primary outcome was the all-cause discontinuation rate between groups. The duration of the study was 2 years.

RESULTS

One hundred eighteen patients were included and analyzed in this study (once-daily dosing group: n = 58; divided dosing group: n = 60). There was no significant difference in all-cause discontinuation between the 2 groups (odds ratio 1.03; 95% confidence interval: [0.28, 3.79]: P = 1.00), or adverse events between groups.

CONCLUSION AND RELEVANCE

In patients with treatment-resistant schizophrenia, there were no significant differences in effectiveness or safety between once-daily and divided dosing of clozapine. Further prospective studies with larger sample sizes are required to confirm these findings.

High rates of myocarditis with clozapine in the Hunter region of Australia

OBJECTIVE

To study the causes of clozapine treatment discontinuation and measure clozapine-induced myocarditis (CIM) rates in an Australian region, to compare the observed rates of CMI with reports from Australia and the world, and discuss factors related to CIM incidence rates in the region.

METHODS

The study is a retrospective clinical audit of 327 patients prescribed clozapine. All patients were monitored by the mandatory CIM monitoring protocol for the first six weeks of treatment. The validity of a diagnosis of CIM was assessed using six criteria. Socio-demographic and clinical factors and clozapine prescription practices were analysed for their association with CIM. The study could not examine co-existing medical illness, co-prescribed psychotropic medication, genetics, and environmental factors.

RESULTS

CIM occurred in 9.8 % of the cohort after a mean treatment duration of 19.5 days. The diagnosis of CIM was considered valid in all cases. Gender, age at the start of treatment, ethnicity, cumulative clozapine dose, dose titration, and clozapine/norclozapine ratio were unrelated to CIM.

CONCLUSION

The CIM rate in the Hunter region was higher than in the rest of Australia and the world and increased after adopting the monitoring protocol. Over-diagnosis, patient's age and gender, ethnicity, cumulative clozapine dose, dosing titration, and clozapine metabolism rate were unrelated to the high occurrence rates. The possible role of comorbid illnesses, co-prescribed psychiatric medications, genetic, and environmental factors in the etiology of CIM requires further study. The reasons underlying the high rates of CIM in the Hunter region need further exploration.

Schizophrenia Patients Discharged on Clozapine Plus Long-Acting Injectable Antipsychotics From a Public Psychiatric Hospital in Taiwan, 2006-2021

BACKGROUND

Some schizophrenia patients treated with clozapine experience an inadequate response and adherence problems. The purpose of this study was to compare time to rehospitalization within 6 months in schizophrenia patients discharged on 3 clozapine regimens. Additionally, the temporal trend of prescription rate in each group was also explored.

METHODS

Schizophrenia patients discharged from the study hospital from January 1, 2006, to December 31, 2021, (n = 3271) were included in the analysis. The type of clozapine prescribed at discharge was divided into 3 groups: clozapine plus long-acting injectable antipsychotics (clozapine + LAIs), clozapine plus other oral antipsychotics (clozapine + OAPs), and clozapine monotherapy. Survival analysis was used to compare time to rehospitalization within 6 months after discharge among the 3 groups. The temporal trend in the prescription rate of each group was analyzed using the Cochran-Armitage Trend test.

RESULTS

Patients discharged on clozapine + LAIs had a significantly longer time to rehospitalization than those on clozapine + OAPs or clozapine monotherapy. The prescription rates of clozapine + LAIs and clozapine + OAPs significantly increased over time, whereas the prescription rates of clozapine monotherapy significantly decreased.

CONCLUSIONS

Compared with the clozapine + OAPs group, the clozapine + LAIs group had a lower risk of rehospitalization and a lower dose of clozapine prescribed. Therefore, if a second antipsychotic is required for patients who are taking clozapine alone, LAIs should be considered earlier.

Clinician Reasons for Stopping Clozapine: A Retrospective Cohort Study

BACKGROUND

Little information is available on clozapine discontinuation rates in developing country settings.

AIM

The present study aimed to evaluate the incidence and reasons clinicians stopped clozapinine in patients after initiating treatment with the same. In addition, the study also aimed to assess the rechallenge rate, that is, restarting clozapine after a decision to discontinue the same by the clinicians.

METHODOLOGY

The treatment records of 859 patients started on clozapine were reviewed to identify the patients for whom the clinician stopped clozapine at least once because of any reason. The reasons for stopping clozapine were reviewed. In addition, the treatment records were also examined for rechallenge with clozapine at a later date.

RESULTS

Clozapine was stopped by the clinicians in 44 of the 859 patients (5.12%). The most common reason for stopping clozapine was blood dyscrasias (n = 12), followed by poor adherence making the hematological monitoring difficult (n = 9), and intolerable sedation (n = 7). In half of the patients (n = 22), clozapine was restarted by the clinicians for further management of schizophrenia. Successful rechallenge was done in 58.33% of patients with blood dyscrasias, 44.44% with poor adherence, and 71.4% with intolerable sedation.

CONCLUSIONS

The present study suggests clinicians stop clozapine in only 5.14% of cases. The most common reasons for clozapine discontinuation by clinicians include blood dyscrasias, poor medication adherence making it challenging to monitor the hemogram, and sedation. However, in half of the patient's clozapine was rechallenged, and all the attempts of rechallenging were successful.

Dropout rates and reasons for dropout among patients receiving clozapine

Background and Aim

The present study aimed to assess the treatment dropout rates, reasons for treatment dropout, and clozapine discontinuation rate among patients attending a tertiary care center in North India.

Materials and Methods

Clozapine data bank was used to identify patients on clozapine, and their treatment records were reviewed for the period Jan 2020-March 2020. Patients who did not follow-up at least once in the last 6 months were considered to have dropped out and were contacted telephonically to understand the reasons for dropout. Treatment records of those following up regularly were reviewed to check if clozapine was discontinued and if so, the reason for the same was evaluated.

Results

Out of 671 patients on clozapine, 495 (73.8%) were still on regular follow-up and the remaining 176 (26.2%) had dropped out of treatment. Out of the 176 patients who had dropped out of treatment, 84 could be contacted. Common reasons for dropout were long distance from the hospital (n = 27), long waiting time for consultation (n = 8), no benefit with treatment (n = 17), side effects with medication (n = 10), moving away to another place (n = 6), refusal by the patient to follow-up (n = 7), patient improved and so did not feel the need to continue treatment (n = 7), and other reasons (n = 37).

Conclusion

About one-fourth of patients who had started treatment with clozapine dropped out from the treatment. The most common reasons for dropout from treatment included long distance from the hospital and no benefit from treatment.

What are patients' experiences of discontinuing clozapine and how does this impact their views on subsequent treatment?

BACKGROUND

Discontinuing what is considered the most effective treatment for treatment-resistant schizophrenia may precipitate feelings of failure or a relapse of illness. Clozapine treatment is discontinued for a variety of reasons, including non-adherence, intolerance, or lack of efficacy. Patients' experiences of discontinuing the "best" treatment and the impact on perceptions of subsequent antipsychotic treatment are important in developing an understanding of the factors affecting people's treatment choices. This study is the first of its type, seeking to explore people's perspectives on clozapine discontinuation.

METHOD

Semi-structured interviews with sixteen patients who had received clozapine and discontinued treatment-thirteen males and three females, age range: thirty-two to seventy-eight years old-were audio-recorded and transcribed. A modified inductive approach to analysis, based on grounded theory, was taken to identify commonalities and differences in patients' perceptions.

RESULTS

The three main themes identified from participants' experiences were: (1) positive and negative effects of treatment; (2) feelings of agency, being the capacity to make decisions about treatment and act independently; (3) choice of treatment in the future. Participants exhibited agency in making choices about medication, including risking relapse, while attempting self-management of medication effects. Different participants perceived the same side effect as beneficial or intolerable. Variation in subsequent treatment choices was reported, with some participants favouring depot (long-acting) injections. A participant was frightened when not told about clozapine's side effects, which led to the participant not being engaged in future treatment decisions. Others, despite suffering serious adverse effects, retained positive perceptions of clozapine; they experienced despair at finding an effective alternative.

CONCLUSIONS

Experiences with clozapine discontinuation evoked powerful emotions and resulted in clozapine being the benchmark for other treatments. Knowledge, agency, and being in control were important to participants in relation to treatment. Personal perceptions of treatments or beliefs about illness could lead to non-adherence. People value the clinician listening to their experiences to better understand their perspective, enabling concerns about medication to be addressed through true shared decision making.

TRIAL REGISTRATION

NHS Health Research Authority and Health and Care Research Wales, IRAS Project ID 225753, Research Ethics Committee (REC) reference: 18/NW/0413, 25/06/2018.

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.

Antipsychotic prescribing practices for outpatients with schizophrenia and reasons for non-clozapine treatment - Data from a Danish quality assessment audit

BACKGROUND

Clozapine is the gold standard for treating treatment-resistant schizophrenia (TRS) although widely underutilised. Both organisational, patient- and clinician related reasons for the underutilisation have been reported, however, the clinical impact of either in real-world settings is not fully elucidated.

AIM

This audit aimed to evaluate the local antipsychotic (AP) prescribing practices for outpatients with schizophrenia and to assess the spectrum and prevalence of journalised reasons for non-clozapine treatment amongst eligible outpatients.

METHODS

Data on demographics, current and former AP treatments, as well as documented reasons for non-clozapine treatment, was extracted through chart audit.

RESULTS

Of the 668 affiliated outpatients with schizophrenia, 43% were treated with AP polytherapy (APP) and 19.6% with clozapine. The most prevalent reason for clozapine discontinuation was related to side effects whereas the most prevalent reason for refusal or omission of clozapine treatment was related to the associated monitoring regimen.

CONCLUSIONS

This audit showed that APP prescribing is a highly prevalent practice in our services when treating outpatients with schizophrenia and that clozapine is underutilised in a 'last resort' manner. The blood-monitoring regimen associated with clozapine treatment was found to be an important factor in the underutilisation. It seemed, however, that the monitoring constituted a barrier for different reasons, requiring different approaches to remedy. Future studies, directly involving both patients and clinicians in the identification and management of the most clinically relevant barriers and their corresponding facilitators, are warranted.

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.

Clozapine haematological monitoring for neutropenia: a global perspective

AIMS

Clozapine is licensed for treatment-resistant psychosis and remains underutilised. This may berelated to the stringent haematological monitoring requirements that are mandatory in most countries. We aimed to compare guidelines internationally and develop a novel Stringency Index. We hypothesised that the most stringent countries would have increased healthcare costs and reduced prescription rates.

METHOD

We conducted a literature review and survey of guidelines internationally. Guideline identification involved a literature review and consultation with clinical academics. We focused on the haematological monitoring parameters, frequency and thresholds for discontinuation and rechallenge after suspected clozapine-induced neutropenia. In addition, indicators reflecting monitoring guideline stringency were scored and visualised using a choropleth map. We developed a Stringency Index with an international panel of clozapine experts, through a modified-Delphi-survey. The Stringency Index was compared to health expenditure per-capita and clozapine prescription per 100 000 persons.

RESULTS

One hundred twocountries were included, from Europe (n = 35), Asia (n = 24), Africa (n = 20), South America (n = 11), North America (n = 7) and Oceania and Australia (n = 5). Guidelines differed in frequency of haematological monitoring and discontinuation thresholds. Overall, 5% of included countries had explicit guidelines for clozapine-rechallenge and 40% explicitly prohibited clozapine-rechallenge. Furthermore, 7% of included countries had modified discontinuation thresholds for benign ethnic neutropenia. None of the guidelines specified how long haematological monitoring should continue. The most stringent guidelines were in Europe, and the least stringent were in Africa and South America. There was a positive association (r = 0.43, p < 0.001) between a country's Stringency Index and healthcare expenditure per capita.

CONCLUSIONS

Recommendations on how haematological function should be monitored in patients treated with clozapine vary considerably between countries. It would be useful to standardise guidelines on haematological monitoring worldwide.

Efficacy and safety of Lu AF35700 in treatment-resistant schizophrenia: A randomized, active-controlled trial with open-label extension

INTRODUCTION

Treatment resistance constitutes the highest burden of disease within schizophrenia. We hypothesized that the synergistic activity of Lu AF35700 at dopamine D1 and D2 receptors might provide superior antipsychotic effects versus first-line antipsychotic therapy in patients with treatment resistant schizophrenia (TRS), with a benign tolerability profile.

METHODS

This was a randomized, double-blind, active-controlled clinical trial (NCT02717195) followed by a one year open-label safety extension (NCT02892422). Following prospective confirmation of treatment resistance, patients were randomized (1:1:1) to 10 weeks double-blind treatment with Lu AF35700 10 mg or 20 mg, or active comparator (risperidone or olanzapine).

RESULTS

1628 patients were screened for TRS, of which 1092 entered the prospective confirmation period. Of these, 697 were randomized (Lu AF35700 10 mg n = 235, 20 mg n = 232, comparator n = 230) and 395 discontinued before randomization, including 264 (24 %) who responded to treatment. 586 patients completed the double-blind phase, of which 524 entered the open-label extension and 318 completed 1-year of open-label treatment. At the end of the double-blind phase, the mean ± SE change in positive and negative syndrome scale (PANSS) total score was -10.1 ± 0.96 for Lu AF35700 10 mg, -8.22 ± 0.98 for Lu AF35700 20 mg, and - 9.90 ± 0.97 for the comparator group. Treatment differences [95 % CI] versus comparator treatment were non-significant (-0.12 [-2.37; 2.13] and 1.67 [-0.59; 3.94], respectively). The most common adverse events with Lu AF35700 were increased weight and headache. Prolactin values decreased by ≥50 % in both sexes treated with Lu AF35700.

CONCLUSIONS

Despite evidence of antipsychotic efficacy, treatment with Lu AF35700 failed to differentiate from conventional antipsychotic treatment for patients with TRS.

Systematic Review of Real-World Treatment Patterns of Oral Antipsychotics and Associated Economic Burden in Patients with Schizophrenia in the United States

Background

Schizophrenia is a chronic mental disorder associated with substantial morbidity and mortality affecting 0.25–1.6% of adults in the USA. Antipsychotic treatment is the standard of care for schizophrenia, but real-world treatment patterns and associated costs have not been systematically reviewed.

Objective

We conducted a systematic review to summarize treatment patterns and associated costs related to oral antipsychotic treatment of patients with schizophrenia in the USA.

Data Sources

We searched Medline (via PubMed) and Embase to identify relevant observational studies published from January 1, 2008, to June 1, 2018; costs were converted to 2018 US dollars.

Study Eligibility

Observational, real-world studies reporting on patterns of treatment and/or associated costs for adult patients with schizophrenia treated with oral antipsychotics in the USA were included.

Results

Eighty-one studies were identified. Frequently prescribed oral second-generation antipsychotics were olanzapine (up to 50.9%), risperidone (up to 40.0%), and quetiapine (up to 30.7%). Suboptimal adherence was common across studies. Antipsychotic switching occurred in about half of patients, while antipsychotic combination therapy occurred in nearly 30%; all were associated with increased medication-related costs. Mean annual direct medical costs differed by treatment, with reported costs of $17,115 to $26,138 for patients treated with olanzapine, $18,395 for risperidone, and $17,656 to $28,101 for quetiapine.

Limitations

This systematic review is limited by the variations in definitions of schizophrenia-related clinical terms used between studies and by the inclusion of studies focused on only the US health care system.

Conclusions

In the treatment of schizophrenia, suboptimal adherence, antipsychotic switching, and antipsychotic augmentation were all associated with high costs of care in comparison to patients who were adherent and did not require antipsychotic switching or augmentation. These findings illustrate the need for the development of new treatments that address efficacy and adherence challenges of currently available therapies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-022-02232-z.

Schizophrenia is a debilitating mental disorder that affects up to 1.6% of adults in the USA. Antipsychotic medications reduce symptoms of the disease, but many patients with schizophrenia are not fully adherent or choose to discontinue treatment entirely, increasing their risk of hospitalization. In others, efforts to achieve better symptom control or to avoid intolerable side effects may result in switching antipsychotic medications or adding additional medications, leading to higher medical treatment costs. The magnitude of these cost increases is unclear. This study sought to assess medical costs associated with antipsychotic treatment adherence, switching, and adding additional antipsychotics. We reviewed 81 studies published from January 2008 through June 2018 examining treatment adherence in patients with schizophrenia. We calculated rates of adherence, switching, and adding antipsychotics, as well as associated medical costs. Overall adherence to antipsychotic treatment was less than 50%, with up to 50% of patients switching medications and up to 29% adding an additional antipsychotic medication to their current treatment. Patients who were not treatment adherent incurred annual medical costs of $10,316 compared with $5723 in patients who were adherent. The costs of immediate or delayed switching of antipsychotic medications ranged from $21,922 to $28,232, while costs of adding an additional antipsychotic ranged from $24,045 to $29,344. These data suggest that suboptimal medication adherence, along with high rates of patient discontinuation and medication switching, lead to higher treatment costs in the management of patients with schizophrenia.

Combination With Long-Acting Injectable Antipsychotics and Utilization of Nonstandard Formulations as Compliance Enhancing Methods for Clozapine Users: A Systematic Review and A Case Series

BACKGROUND

Combining clozapine with a long-acting injectable antipsychotic (LAI) or using different, nonstandard formulations of the compound may improve treatment outcomes. We aimed to investigate the utility of the clozapine-LAI combination and different formulations of clozapine for compliance problems of clozapine treatment, and to describe a case series on the combined treatment.

PROCEDURES

We conducted a PubMed search with no date restriction. The number and length of hospitalizations, the results of clinical scales, and adverse events were recorded. We also present a case series of 18 patients using the clozapine-LAI combination. Data were collected from the medical charts and electronic records.

RESULTS

We extracted 9 records describing the use of the clozapine-LAI combination. The case reports and mirror-image studies showed a significant reduction in the number of hospitalizations, length of hospital stays, and number of visits to the emergency department on the combined treatment with no serious adverse events. We included 11 articles for clozapine formulations. The case reports and retrospective data suggested that short-acting intramuscular clozapine was often well tolerated and resulted in an increased acceptance of oral clozapine in the acute phase of illness. In our case series, illness severity and the number of hospitalization per year significantly decreased after the combined treatment, besides a significant improvement in the functioning scores. Hyperprolactinemia and extrapyramidal side effects were reported due to concomitant LAIs.

CONCLUSIONS

Despite the encouraging evidence, the present data are preliminary and mostly based on retrospective studies, and oral-dissolving tablets or oral liquid formulations of clozapine have insufficient evidence for clinical practice. Well-designed, controlled, follow-up studies are needed for both clozapine-LAI combination and different formulations of clozapine.

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.

Clozapine- and non-clozapine-associated neutropenia in patients with schizophrenia: a retrospective cohort study

INTRODUCTION

The antipsychotic drug clozapine remains underutilized partly because of the risk of life-threatening adverse effects, such as neutropenia. Therefore, an extensive hematological monitoring program was set up to detect neutropenia.

METHODS

In this retrospective cohort study, we used registry-based data from the Capital Region of Denmark to investigate incidence rates of neutropenia among patients with a diagnosis of schizophrenia or other psychotic disorders and treated with clozapine for the first time. In a within-subject design, we compared rates of neutropenia in time periods where patients were exposed to clozapine versus time periods, where they were not exposed to clozapine. We also investigated whether the lengths of clozapine-associated neutropenia (CAN) were related to discontinuation of clozapine treatment.

RESULTS

Data from 520 clozapine users were included. The incidence rate of CAN was 3.2 cases per 100 person-years (95% confidence interval [CI]: 2.1-4.8) throughout the entire study. There was no significant difference in incidence rates of neutropenia during clozapine exposure and non-clozapine exposure, with an incidence rate ratio of 0.7 (95% CI: 0.4-1.3). One episode of severe neutropenia was detected. Episodes of CAN with only one sub-threshold neutrophil count were not associated with higher clozapine discontinuation (26%) than CAN episodes of more than one sub-threshold neutrophil count (28%).

CONCLUSION

In the present study, we could not confirm that clozapine treatment was associated with neutropenia.

Post-clozapine in a clinical setting: A retrospective case note review in Kumamoto, Japan (2009-2019)

Clozapine is commonly prescribed in dopamine supersensitivity psychosis (DSP) cases in Japan. However, limited knowledge on treatment post-clozapine discontinuation use exists. We investigated antipsychotic medications, patient status, and DSP episodes before, during, and after clozapine treatment using medical records of 30 schizophrenia patients (mean age, 51 years; mean illness duration before clozapine treatment, 24 years; mean clozapine treatment duration, 1.6 years), who discontinued clozapine between 2009 and 2019. In our region, long-acting injectable antipsychotic monotherapy and polypharmacy (half with aripiprazole) accounted for 17% and 50% post-clozapine use, respectively. Furthermore, patient status rarely improved with subsequent DSP treatment, including clozapine re-initiation.

Cluster Analysis of Clozapine Consumer Perspectives and Comparison to Consumers on Other Antipsychotics

Despite its unique efficacy, clozapine remains underutilized in the United States. Perceptions about clozapine and barriers to its use have been examined among prescribers, but insufficiently studied among consumers. We surveyed 211 antipsychotic consumers (86 on clozapine and 125 on other antipsychotics) on their medication-related perspectives in a public hospital system in Atlanta, Georgia, USA. In contrast to their previous regimen, 72% of clozapine consumers reported they were more satisfied with clozapine. When compared with consumers taking other antipsychotics, clozapine consumers reported more side effects but did not differ on other measures of satisfaction or efficacy. We found Caucasians to be overrepresented among clozapine, as compared to other antipsychotic consumers. Side effects most strongly associated with poor safety ratings were sedation, limb jerking, and dizziness when standing. However, clozapine was only rated less safe by consumers who experienced more than one of these side effects. We used an unsupervised clustering approach to identify three major groups of clozapine consumers. Cluster A (19%) had the lowest safety ratings, aversion to blood work, and a high rate of side effects that associate with lower safety ratings. Cluster B (25%) experienced more hospitalizations and reported satisfaction with clozapine that correlated with efficacy ratings, irrespective of safety ratings. Cluster C (56%) experienced fewer hospitalizations, fewer previous drug trials, greater educational attainment, lower rates of smoking, and rated clozapine more highly. This work identifies common side effects that influence the subjective safety of clozapine and suggests that attitudes toward clozapine depend on context-specific factors.

Reducing the Risk of Withdrawal Symptoms and Relapse Following Clozapine Discontinuation-Is It Feasible to Develop Evidence-Based Guidelines?

Clozapine is the only antipsychotic that is effective in treatment-resistant schizophrenia. However, in certain clinical situations, such as the emergence of serious adverse effects, it is necessary to discontinue clozapine. Stopping clozapine treatment poses a particular challenge due to the risk of psychotic relapse, as well as the development of withdrawal symptoms. Despite these challenges for the clinician, there is currently no formal guidance on how to safely to discontinue clozapine. We assessed the feasibility of developing evidence-based recommendations for (1) minimizing the risk of withdrawal symptoms, (2) managing withdrawal phenomena, and (3) commencing alternatives treatment when clozapine is discontinued. We then evaluated the recommendations against the Appraisal of Guidelines for Research and Evaluation (AGREE) II criteria. We produced 19 recommendations. The majority of these recommendation were evidence-based, although the strength of some recommendations was limited by a reliance of studies of medium to low quality. We discuss next steps in the refinement and validation of an evidence-based guideline for stopping clozapine and identify key outstanding questions.

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.

Integration analysis of GWAS and expression quantitative trait loci to identify candidate genes and pathways for clozapine-related neutropaenia

AIMS

Little is known about the genetic basis of clozapine-related neutropaenia. This study aims to explore candidate genes and pathways involved in clozapine-related neutropaenia.

METHODS

This study conducted a two-stage integrative analysis of the summary statistics from the genome-wide association study (GWAS, n = 552) of the lowest absolute neutrophil count (ANC) during clozapine treatment and the summary data of the expressed quantitative trait locus (eQTL). First, we use the probabilistic Mendelian randomization (PMR-Egger) to identify genes whose expression is causally related to ANC, and then use Bayesian co-localization analysis to investigate whether there are shared causal variants between them [posterior probability for hypotheses 4 (PP.H4) > 0.80]. Finally, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were conducted to explore the pathways that may be associated with ANC during clozapine treatment.

RESULTS

PMR-Egger analysis identified 146 genes that may be causally associated with ANC after Bonferroni correction (P-value < 3.25e-6). Bayesian co-localization analysis identified six further genes whose gene expression shared common variants with ANC, including NT5E (PP.H4 = 0.96), GLDC (PP.H4 = 0.82), NUDT17 (PP.H4 = 0.88), MSH4 (PP.H4 = 0.88), PTER (PP.H4 = 0.89) and SERPINB6 (PP.H4 = 0.83). Enrichment analysis identified 52 GO terms and seven pathways associated with ANC, such as NAD metabolic process, drug catabolic process and glyoxylate and dicarboxylate metabolism.

CONCLUSION

This study identified multiple candidate genes and pathways that may be involved in clozapine-related neutropaenia, providing novel clues for the mechanism of clozapine-related neutropaenia.

Daily functioning and symptom factors contributing to attitudes toward antipsychotic treatment and treatment adherence in outpatients with schizophrenia spectrum disorders

BACKGROUND

Poor adherence and negative attitudes to treatment are common clinical problems when treating psychotic disorders. This study investigated how schizophrenia core symptoms and daily functioning affect treatment adherence and attitudes toward antipsychotic medication and to compare patients using clozapine or other antipsychotics.

METHOD

A cross-sectional study with data from 275 patients diagnosed with schizophrenia spectrum disorder. Patients adherence, attitudes, insight and side-effects were evaluated using the Attitudes toward Neuroleptic Treatment scale. Overall symptomology was measured using the Brief Psychiatric Rating Scale (BPRS), the Health of the Nation Outcome Scale (HoNOS). The functioning was assessed using activities of daily living scale, instrumental activities of daily living scale and social functioning of daily living scale.

RESULTS

Self-reported treatment adherence was high. Of the patients, 83% reported using at least 75% of the prescribed medication. Having more symptoms was related with more negative attitude towards treatment. There was a modest association with functioning and treatment adherence and attitude toward antipsychotic treatment. Attitudes affected on adherence in non-clozapine but not in clozapine groups.

CONCLUSION

Early detection of non-adherence is difficult. Systematic evaluation of attitudes toward the treatment could be one way to assess this problem, along with optimized medication, prompt evaluation of side effects and flexible use of psychosocial treatments.

Absolute and Dose-Adjusted Serum Concentrations of Clozapine in Patients Switching vs. Maintaining Treatment: An Observational Study of 1979 Patients

BACKGROUND

Clozapine is an effective drug for the management of schizophrenia that has not responded to other agents, but some patients experience insufficient or adverse effects and discontinue treatment.

OBJECTIVE

We investigated a potential association between clozapine serum concentrations and switching to other antipsychotics in a large real-world patient population from a therapeutic drug monitoring service.

METHODS

Absolute and dose-adjusted serum concentrations (concentration-to-dose ratios [C/D ratios]) of clozapine during dosing between 100 and 1000 mg/day were measured in 1979 Norwegian patients during the period 2005-2019. These variables were compared in patients switching to other antipsychotic drugs versus maintaining clozapine treatment using linear mixed models. Smoking habits were known for 49% of the patients. To prevent potential nonadherence affecting clozapine switching, only patients with serum concentrations above 50% of the lower reference range were included.

RESULTS

In total, 190 patients (9.6%) switched from clozapine to another antipsychotic drug during the study period, whereas the remaining patients were not detected as switchers and were interpreted as maintaining treatment. Patients switching treatment had 23.5% lower absolute concentrations (954 vs. 1245 nmol/L; p < 0.001) and 15.7% lower daily doses (305 vs. 362 mg/day; p < 0.001) of clozapine than did nonswitchers, making the clozapine C/D ratio 9.7% lower in switchers than in nonswitchers after correcting for smoking habits (2.80 vs. 3.10 nmol/L/mg/day; p = 0.032).

CONCLUSIONS

The present study suggests that decreased absolute and dose-adjusted serum concentrations of clozapine were associated with clozapine discontinuation. The significantly reduced clozapine concentrations regardless of prescribed dose in switchers versus nonswitchers may indicate a pharmacokinetic mechanism underlying the risk of clozapine discontinuation.

Clozapine in the treatment of refractory schizophrenia: a practical guide for healthcare professionals

BACKGROUND

Clozapine remains the only medication licensed for treating refractory schizophrenia. However, it remains underutilized in part due to concerns regarding adverse events.

SOURCES OF DATA

Published literature.

AREAS OF AGREEMENT

Common adverse events during clozapine treatment include sedation, hypersalivation, postural hypotension, dysphagia, gastrointestinal hypomotility, weight gain, diabetes mellitus and dyslipidaemia. Rare but serious events include agranulocytosis, cardiomyopathy, myocarditis, pneumonia, paralytic ileus and seizure.

AREAS OF CONTROVERSY

It remains unclear how best to minimize clozapine-induced morbidity/mortality (i) during dose titration, (ii) from hypersalivation and (iii) from gastrointestinal hypomotility. It is also unclear how clozapine pharmacokinetics are affected by (i) gastrointestinal hypomotility, (ii) systemic infection and (iii) passive exposure to cigarette smoke. Whether monthly haematological monitoring needs to continue after 12 months of uninterrupted therapy is also a subject of debate.

GROWING POINTS

There is a need for better management of serious clozapine-related adverse events in addition to agranulocytosis. There is also a need for better education of patients and carers, general practitioners, A&E and ITU staff and others of the problems posed in using clozapine safely.

AREAS TIMELY FOR DEVELOPING RESEARCH

There is a need for more research on assessing clozapine dosage (i) as patients get older, (ii) with respect to exposure to cigarette smoke and (iii) optimizing response if adverse events or other factors limit dosage.

How and when to use clozapine

OBJECTIVE

Clozapine is the only approved strategy for treatment-resistant schizophrenia, although it is highly underutilized. We aim to generate practical and actionable evidence-based recommendations for the use of this drug considering prescription barriers.

METHOD

Narrative review.

RESULTS

A consistent body of evidence supports the efficacy of clozapine reducing morbidity and mortality in schizophrenia. The main obstacles to its use are the lack of experience by prescribers and perceived treatment burden. Systematic screening of eligibility, utilization of available resources for consultation, developing a professional network with other stakeholders, as well as optimizing how clozapine is presented to patients is discussed. Furthermore, specific evidence-based recommendations for initiation, maintenance, and safety monitoring with clozapine are provided.

CONCLUSION

Clozapine prescription is one of the areas in psychiatry with the greatest mismatch between efficacy and utilization in clinical practice. Although multiple barriers to the use of clozapine exist, some of these may be overcome by updates of routine clinical practice.

Clinical determinants of fever in clozapine users and implications for treatment management: A narrative review

OBJECTIVES

To identify the clinical determinants of fever in clozapine users and their impact on management of clozapine treatment.

METHODS

Articles published in English or French identified with a MEDLINE, Web of Sciences, Cochrane Library and PsycINFO search, from inception through February 2019, using the term "clozapine" in combination with "fever" OR "hyperthermia" OR "body temperature" OR "pyrexia" OR "febrile" OR "heat" OR "thermoregulation". Information extracted for each medical condition were frequency, time to onset after initiation of clozapine treatment, characteristics of fever, associated symptoms, laboratory tests used for diagnosis, course, lethality, discontinuation of clozapine. Data were synthesized narratively.

RESULTS

Our search yielded 394 unique hits published from 1993 to 2018. We included 73 articles in the review: two meta-analyses, 14 reviews, six epidemiological studies, 11 clinical studies and 40 case reports. During clozapine initiation, fever is most frequently benign and transient but should be closely monitored as it may be the first stage of potentially life-threatening adverse drug reactions (ADR) (agranulocytosis, neuroleptic malignant syndrome myocarditis, hepatitis, pancreatitis, nephritis, colitis, etc.). Other ADR associated with fever are independent of duration of exposure to clozapine (heat stroke, pneumonia, pulmonary embolism, necrotizing colitis). If fever is due to intercurrent infection, therapeutic drug monitoring is recommended to adjust clozapine daily dosage.

CONCLUSION

Benign causes of fever are much more frequent than life-threatening ADR during clozapine treatment. Discontinuation should not be considered as automatic in the event of fever, especially during the early phase of clozapine initiation.

Reasons for clozapine discontinuation in patients with treatment-resistant schizophrenia

Although clozapine is more effective than other antipsychotics in the treatment of schizophrenia, the rate of its discontinuation is also high. The aim of this retrospective chart-review study was to investigate the causes of clozapine discontinuation in patients with treatment-resistant schizophrenia. This study included a total of 396 patients with schizophrenia, 240 still on clozapine therapy and 156 who discontinued clozapine, and compared their clinical characteristics. Those who discontinued clozapine had a longer history of illness and more hospitalizations before clozapine and tended to be older. Inadequate response was more common among clozapine discontinuers compared to continuers. The most common reason for discontinuation was the side-effects associated with clozapine (49%). Discontinuation from patient decision or by the psychiatrist due to noncompliance was the second (29.7%) and discontinuation due to lack of efficacy was the third most frequent reason (21.3%). The patients who discontinued clozapine because of cardiac side effects were younger, had shorter duration of clozapine use, and had lower maximum clozapine dose compared to the other discontinuers. Our findings point out the importance of enhancing psychiatrists' ability to handle manageable side effects to minimize discontinuations and maximize the benefits of clozapine in patients with treatment-resistant schizophrenia.

Clozapine and Long-Term Mortality Risk in Patients With Schizophrenia: A Systematic Review and Meta-analysis of Studies Lasting 1.1-12.5 Years

INTRODUCTION

Patients with schizophrenia have an elevated mortality risk compared to the general population, with cardiovascular-related deaths being the leading cause. The role of clozapine use in the long-term mortality risk is unclear. While clozapine treatment may increase the risk for cardiovascular mortality, it may have protective effects regarding suicidal behavior.

METHODS

We systematically searched EMBASE, MEDLINE, and PsycINFO and reviewed studies that used a long-term follow-up (ie, >52 weeks) and reported on mortality in adults diagnosed with schizophrenia-spectrum disorders who had received clozapine treatment.

RESULTS

Altogether, 24 studies reported on 1327 deaths from any causes during 217691 patient years in patients treated with clozapine. The unadjusted mortality rate in 22 unique samples during a follow-up of 1.1-12.5 (median = 5.4) years was 6.7 (95% confidence interval [CI] = 5.4-7.9) per 1000 patient years. Long-term, crude mortality rate ratios were not significantly lower in patients ever treated with clozapine during follow-up, but significantly lower in patients continuously treated with clozapine compared to patients with other antipsychotics (mortality rate ratio = 0.56, 95% CI = 0.36-0.85, P-value = .007). Few studies reported on rates of long-term cause-specific mortality (suicide and ischemic heart disease), which showed no significant difference in patients using clozapine compared to patients using other antipsychotics. Statistical heterogeneity was high in all analyses.

DISCUSSION

Continuous clozapine treatment in schizophrenia patients was associated with a significantly lower long-term all-cause mortality rate compared to other antipsychotic use. These findings, combined with the known efficacy of clozapine, give reason to re-evaluate the hesitancy to prescribe clozapine in regular care settings.

TRIAL REGISTRATION

PROSPERO CRD42017069390.

A genome-wide association study in individuals of African ancestry reveals the importance of the Duffy-null genotype in the assessment of clozapine-related neutropenia

Individuals of African ancestry in the United States and Europe are at increased risk of developing schizophrenia and have poorer clinical outcomes. The antipsychotic clozapine, the only licensed medication for treatment-resistant schizophrenia, is under-prescribed and has high rates of discontinuation in individuals of African ancestry, due in part to increased rates of neutropenia. The genetic basis of lower neutrophil levels in those of African ancestry has not previously been investigated in the context of clozapine treatment. We sought to identify risk alleles in the first genome-wide association study of neutrophil levels during clozapine treatment, in 552 individuals with treatment-resistant schizophrenia and robustly inferred African genetic ancestry. Two genome-wide significant loci were associated with low neutrophil counts during clozapine treatment. The most significantly associated locus was driven by rs2814778 (β = -0.9, P = 4.21 × 10^-21), a known regulatory variant in the atypical chemokine receptor 1 (ACKR1) gene. Individuals homozygous for the C allele at rs2814778 were significantly more likely to develop neutropenia and have to stop clozapine treatment (OR = 20.4, P = 3.44 × 10^-7). This genotype, also termed "Duffy-null", has previously been shown to be associated with lower neutrophil levels in those of African ancestry. Our results indicate the relevance of the rs2814778 genotype for those taking clozapine and its potential as a pharmacogenetic test, dependent on the outcome of additional safety studies, to assist decision making in the initiation and on-going management of clozapine treatment.

Predicting Unsuccessful Clozapine Treatment After First Use in Adult Patients With Psychotic Disorders

PURPOSE/BACKGROUND

Cessation of clozapine therapy and insufficient response may result in relapse of psychotic symptoms and in clinical admissions. However, discontinuation rates are high. Identifying patients at risk for unsuccessful clozapine use might enable clinicians to direct specific attention to them.

METHODS/PROCEDURES

Routinely collected data from a large insurance company were used to develop a simple prediction model for unsuccessful clozapine treatment in psychiatric patients 1 year after clozapine was first dispensed by a community pharmacy in the Netherlands. Multivariate logistic regression analyses were performed with the Nagelkerke R statistic as a measure of the predictive value of the model.

FINDINGS/RESULTS

A total of 937 patients were dispensed clozapine for the first time by their community pharmacy between January 1, 2011, and December 31, 2015 (index date). Of these, 741 patients had started their clozapine treatment in hospital before the index date (inpatient starters); the remaining 196 patients started clozapine as outpatients on the index date (outpatient starters). In 191 patients (20.4%), clozapine treatment was unsuccessful 1 year after the index date. Unsuccessful treatment was more common among outpatient starters than among inpatient starters (32.1% vs 17.3%). Using backward selection of the variables, a model consisting of 61 variables had the best predictive value overall (Nagelkerke R = 0.301), whereas a model consisting of 52 variables had the best predictive value in outpatient starters (Nagelkerke R = 0.676).

IMPLICATIONS/CONCLUSIONS

The likelihood of unsuccessful clozapine treatment after 1 year was higher among patients who started clozapine as outpatients. Despite the use of a diversity of variables and different statistical approaches, it was not possible to make a simple prediction model for unsuccessful clozapine treatment using relatively easily accessible data.

Treatment resistant schizophrenia - review and a call to action

Recovery rates in schizophrenia remain suboptimal with up to one-third resistant to standard treatments, a population prevalence of 0.2%. Clozapine is the only evidenced-based treatment for treatment resistant schizophrenia (TRS), yet there are significant delays in its use or it may not be trialled, potentially impacting the chance of recovery. Better outcomes with earlier use of clozapine may be possible. There is emerging evidence that early treatment resistance is not uncommon from the earliest stages of psychosis. In this review, we provide an update on TRS, its epidemiology and its management, with a specific focus on the optimal use and timing of clozapine and augmentation strategies for the one-third of patients who do not respond to clozapine.

Long-term follow-up of clozapine prescribing

OBJECTIVE

Clozapine is uniquely effective for treatment-resistant schizophrenia, and so treatment continuation is essential. We aimed to identify factors associated with an increased likelihood of clozapine discontinuation in a cohort of patients in South East London.

METHODS

We gathered demographic and treatment information such as duration of illness and antipsychotic treatment history. t-tests, chi-square tests and binary logistic regression were used to compare patients who continued and discontinued clozapine during the study and to identify predictor variables for discontinuation.

RESULTS

Out of the study population of 133 patients, 48 discontinued clozapine at least once during the study period. The majority of these (75%) stopped treatment within the first 4 years of clozapine therapy. Age, ethnicity, diagnosis and antipsychotic treatment history were not predictive of the risk of clozapine discontinuation. However, male patients were more likely to stop taking clozapine (χ² = 6.81, p = 0.009). The odds of discontinuing clozapine were 2.15 times higher for male patients. The most common reason for discontinuation was patient refusal of treatment.

CONCLUSION

We found that patients who discontinue clozapine are more likely to be male, but no other demographic variable was found to predict treatment cessation. Discontinuation usually occurred due to patient refusal of treatment.

Clozapine discontinuation in early schizophrenia: a retrospective case note review of patients under an early intervention service

AIM

Research in patients with treatment-resistant schizophrenia has demonstrated that clozapine discontinuation is associated with poor outcomes. There is, however, a paucity of research investigating the impact of clozapine discontinuation specifically in younger patients with more recent onset schizophrenia. A case note review was therefore conducted to ascertain medium-term prognoses in patients with treatment-resistant schizophrenia under an early intervention service (EIS) following clozapine discontinuation.

METHODS

The case notes of 25 patients under the care of Birmingham EIS who discontinued clozapine were examined retrospectively. Reasons for discontinuation were recorded. Clinical outcomes including total duration of inpatient or home treatment admission, antipsychotic dose, number of alternative antipsychotics prescribed and adverse events were recorded for both the year before and the year after stopping clozapine. Statistical comparisons of pre- and post-discontinuation clinical outcomes determined whether discontinuation had negative effects.

RESULTS

There was no significant difference between the pre- and post-discontinuation clinical status following clozapine discontinuation. More than half (56%) of patients remained stable after stopping clozapine. Mean inpatient or home treatment stay rose from 29.7 to 62.6 days (p = 0.155), total antipsychotic dose from 50.1% of British National Formulary (BNF) limits to 60.5% (p = 0.627), number of alternative antipsychotics prescribed from 1.28 to 1.80 (p = 0.186), number of hospital/home treatment episodes from 0.20 to 0.44 (p = 0.083) and number of adverse events from 0 to 0.20 (p = 0.059). Non-compliance was the main reason for discontinuation (44%, n = 11).

CONCLUSIONS

This is the first clozapine discontinuation study specifically considering EIS patients. Discontinuation did not lead to significant effects on 1 year outcomes, though the study is underpowered. These findings may be used to inform future prospective cohort discontinuation studies.

Neutropenia and agranulocytosis during treatment of schizophrenia with clozapine versus other antipsychotics: an observational study in Iceland

BACKGROUND

Data on the haematological outcomes of patients who continue clozapine treatment following neutropenia are very rare as even mild neutropenia results in mandatory discontinuation of clozapine in most countries. However, in Iceland where clozapine monitoring is less stringent allows an observational study to be done on the risk of agranulocytosis and neutropenia during treatment with clozapine compared with other antipsychotics among patients with schizophrenia.

METHODS

The present study is a part of a wider ongoing longitudinal study of schizophrenia in Iceland. We identified 201 patients with schizophrenia treated with clozapine and 410 patients with schizophrenia who had never been on clozapine by searching the electronic health records of Landspitali, the National University Hospital. Neutrophil counts were searched in electronic databases to identify patients who developed neutropenia/agranulocytosis and the frequency of neutrophil measurements was examined as well.

RESULTS

The median number of days between neutrophil measurements during the first 18 weeks of clozapine treatment was 25 days but after the first 18 weeks on the drug the median became 124 days. Thirty four cases of neutropenia were identified during clozapine treatment with an average follow up time of 9.2 years. The majority, 24 individuals developed mild neutropenia (1500-1900 neutrophils/mm³). None of these progressed to agranulocytosis. The remaining 10 patients developed neutropenia in the range 500-1400 /mm³ of whom one developed agranulocytosis, three stopped clozapine use and 6 patients continued on clozapine for at least a year without developing agranulocytosis. Unexpectedly, schizophrenia patients on other antipsychotics had an equal risk of developing neutropenia as those on clozapine.

CONCLUSIONS

Neutropenia is common both in patients with schizophrenia on clozapine treatment and in those never on clozapine. Therefore a large part of neutropenia during clozapine treatment is probably not caused by clozapine. These findings have implications in assessing the balance between the risk of progression from neutropenia to agranulocytosis against the morbidity resulting from the premature discontinuation of clozapine under the current monitoring regulations in the US and in most of Europe.

Treatment-resistant schizophrenia: current insights on the pharmacogenomics of antipsychotics

Up to 30% of people with schizophrenia do not respond to two (or more) trials of dopaminergic antipsychotics. They are said to have treatment-resistant schizophrenia (TRS). Clozapine is still the only effective treatment for TRS, although it is underused in clinical practice. Initial use is delayed, it can be hard for patients to tolerate, and clinicians can be uncertain as to when to use it. What if, at the start of treatment, we could identify those patients likely to respond to clozapine - and those likely to suffer adverse effects? It is likely that clinicians would feel less inhibited about using it, allowing clozapine to be used earlier and more appropriately. Genetic testing holds out the tantalizing possibility of being able to do just this, and hence the vital importance of pharmacogenomic studies. These can potentially identify genetic markers for both tolerance of and vulnerability to clozapine. We aim to summarize progress so far, possible clinical applications, limitations to the evidence, and problems in applying these findings to the management of TRS. Pharmacogenomic studies of clozapine response and tolerability have produced conflicting results. These are due, at least in part, to significant differences in the patient groups studied. The use of clinical pharmacogenomic testing - to personalize clozapine treatment and identify patients at high risk of treatment failure or of adverse events - has moved closer over the last 20 years. However, to develop such testing that could be used clinically will require larger, multicenter, prospective studies.

Clozapine administration in clinical practice: once-daily versus divided dosing

OBJECTIVE

While it is recommended that clozapine be administered in a divided dosing regimen, it is unclear whether this recommendation is followed in real-world clinical practice. In two large datasets, we examined clozapine dosing frequency and patient characteristics across different dosing regimens.

METHOD

We conducted a cross-sectional survey, collecting data on patients receiving clozapine in August/September 2015 from the Centre for Addiction and Mental Health (CAMH) in Toronto, Canada, and The Zucker Hillside Hospital (ZHH) in New York, United States.

RESULTS

Of 676 and 308 patients included in CAMH and ZHH datasets, clozapine was prescribed once daily in 75.1% and 74.4%, even though doses exceeding 200 mg/day were administered in 88.6% and 84.4% of the respective samples. No significant difference was found in the rates of positive symptom remission between once-daily vs. divided dosing (79.7% vs. 80.5%, P = 1.00). Higher clozapine dose and use of anticholinergic medications were significantly associated with divided dosing in both datasets. Older age or male gender was related to divided dosing in CAMH or ZHH dataset respectively.

CONCLUSION

Despite the product monograph recommendation, clozapine is frequently prescribed once daily in North America. Further studies are needed to compare clinical outcomes between once-daily vs. divided clozapine dosing.

Reasons for discontinuing clozapine: A cohort study of patients commencing treatment

BACKGROUND

Clozapine is uniquely effective in the management of treatment-resistant schizophrenia (TRS). However, a substantial proportion of patients discontinue treatment and this carries a poor prognosis.

METHODS

We investigated the risk factors, reasons and timing of clozapine discontinuation in a two-year retrospective cohort study of 316 patients with TRS receiving their first course of clozapine. Reasons for discontinuation of clozapine and duration of treatment were obtained from case notes and Cox regression was employed to test the association of baseline clinical factors with clozapine discontinuation.

RESULTS

A total of 142 (45%) patients discontinued clozapine within two years. By studying the reasons for discontinuations due to a patient decision, we found that adverse drug reactions (ADRs) accounted for over half of clozapine discontinuations. Sedation was the most common ADR cited as a reason for discontinuation and the risk of discontinuation due to ADRs was highest in the first few months of clozapine treatment. High levels of deprivation in the neighbourhood where the patient lived were associated with increased risk of clozapine discontinuation (HR=2.12, 95% CI 1.30-3.47).

CONCLUSIONS

Living in a deprived neighbourhood was strongly associated with clozapine discontinuation. Clinical management to reduce the burden of ADRs in the first few months of treatment may have a significant impact and help more patients experience the benefits of clozapine treatment.

Pharmacological interventions for clozapine-induced sinus tachycardia

BACKGROUND

Clozapine is an efficacious treatment for treatment-resistant schizophrenia; however its use can be limited by side effect intolerability. Sinus tachycardia is a common adverse event associated with clozapine treatment. Various pharmacological treatments are used to control heart rate increase due to clozapine use and can include a decreased rate of clozapine titration, a switch to a different antipsychotic, or treatment with negative chronotropic drugs.

OBJECTIVES

To assess the clinical effects and efficacy of pharmacological interventions for clozapine-induced sinus tachycardia.To systematically review the adverse events associated with pharmacological interventions for clozapine-induced sinus tachycardia.

SEARCH METHODS

On 23 March 2015, we searched the Cochrane Schizophrenia Group's Study-Based Register of Trials, which is based on regular searches of CINAHL, BIOSIS, AMED, EMBASE, PubMed, MEDLINE, PsycINFO and registries of clinical trials. There are no language, date, document type or publication status limitations for inclusion of records in the register.

SELECTION CRITERIA

Randomised controlled trials comparing pharmacological interventions, at any dose and by any route of administration, for clozapine-induced tachycardia.

DATA COLLECTION AND ANALYSIS

We independently screened and assessed studies for inclusion using pre-specified inclusion criteria.

MAIN RESULTS

The electronic searches located three references. However, we did not identify any studies that met our inclusion criteria.

AUTHORS' CONCLUSIONS

With no studies meeting the inclusion criteria, it is not possible to arrive at definitive conclusions. There are currently insufficient data to confidently inform clinical practice. We cannot, therefore, conclude whether specific interventions, such as beta-blockers, are less effective or more effective than standard courses of alternative treatments for tachycardia. This lack of evidence for the treatment of clozapine-induced tachycardia has implications for research and practice. Well-planned, conducted and reported randomised trials are indicated. One trial is currently underway. Current practice outside of well-designed randomised trials should be clearly justified.

Risk of New-Onset Diabetes After Long-Term Treatment With Clozapine in Comparison to Other Antipsychotics in Patients With Schizophrenia

It has been suggested that clozapine has one of the largest diabetic effects of all atypical antipsychotics. To confirm these findings, we examined retrospectively the risk of new-onset diabetes in long-term clozapine treatment compared to treatment with other antipsychotics in a matched control population with schizophrenia or schizoaffective disorder. Ninety-four adult patients with schizophrenia or schizoaffective disorder who had been treated with clozapine for 5 years or longer were matched on age, diagnosis, and sex to 94 patients without any use of clozapine. The groups were followed up for as long as 20 years. The cumulative incidence of new detection of diabetes in the clozapine group was 22.3% (mean follow-up, 12.3 years; absolute risk difference, 6.3%; 95% confidence interval, -4.9% to 17.5%). An additional rigorous analysis of the 83 matched pairs with normal glucose measurement before end point showed a significant risk difference between the 2 groups (21.7% compared with 8.4%) but may have been biased against clozapine. We conclude that definitive evidence showing a clinically significant larger risk for new-onset diabetes after long-term treatment with clozapine in comparison to other antipsychotics is lacking.

The Effect of Clozapine on Hematological Indices: A 1-Year Follow-Up Study

Clozapine is the antipsychotic of choice for treatment-resistant schizophrenia and is linked to a need for mandatory hematological monitoring. Besides agranulocytosis, other hematological aberrations have resulted in premature termination in some cases. Considering clozapine's role in immunomodulation, we proceeded to investigate the impact of clozapine on the following 3 main hematological cell lines: red blood cells, platelets, white blood cells (WBCs), and its differential counts. Data were extracted from patients initiated on clozapine between January 2009 and December 2010 at a single hospital. Patients with a preclozapine complete blood count, who were receiving clozapine during the 1-year follow-up period, were included in the present investigation. Counts of red blood cells, platelets, WBC, and its differential including neutrophils, lymphocytes, monocytes, eosinophils, and basophils were extracted and trajectories plotted. One hundred one patients were included in this study and 66 remained on clozapine at the end of 1 year. There was a synchronized but transient increase in WBC, neutrophils, monocytes, eosinophils, basophils, and platelets beginning as early as the first week of clozapine treatment. There were no cases of agranulocytosis reported in this sample, and five developed neutropenia. A spike in neutrophils immediately preceded the onset of neutropenia in three of the five. The cumulative incidence rates were 48.9% for neutrophilia, 5.9% for eosinophilia, and 3% each for thrombocytosis and thrombocytopenia. Early hematological aberrations are visible across a range of cell lines, primarily of the myeloid lineage. These disturbances are transient and are probably related to clozapine's immunomodulatory properties. We do not suggest discontinuing clozapine as a consequence of the observed aberrations.

Optimization of psychopharmacotherapy for schizophrenia in a male, locked, non-acute unit serving for persistently ill patients over one year

We describe real-world psychopharmacological treatment in a Japanese, male, closed psychiatric unit where clozapie was still unavailable. Fifty-five persistently-ill patients with schizophrenia (ICD-10), mean ± S.D. age: 57.5 ± 13.0 y.o., duration of illness and admissions: 30.9 ± 15.2 years and 20.7 ± 14.5 years, respectively) treated longitudinally were evaluated. The rule was to treat with a simplest possible psychotropic regimen without polypharmacy. Compared to the baseline, the number and dose of antipsychotics were reduced from 1.9 to 1.1 and 1012 mg/day to 607 mg/day, respectively. The number of total psychotropics was minimized from 4.7 to 2.1, with a simplified once or twice daily dosing. Overall, the CGI-Severity and FACT-Sz (global functioning) improved slightly from 5.8 to 5.5 and 28.7 to 32.6, respectively. Of note, no patients got worse in comparison with the baseline clinical presentation. Forty-four patients were successfully treated with a single antipsychotic; only seven needed two antipsychotics simultaneously while 36 had been treated with antipsychotic polypharmacy at baseline. Benzodiazepines (mostly lorazepam) and antiparkinsonian drugs were prescribed in 28 and only two, respectively. Nineteen needed adjunctive valproate (average blood levels: 99.3 ± 21.8 μg/mL) and nine used lithium (0.61 ± 0.26 mEq/L). Optimization of psychopharmacotherapy is still possible for difficult-to-treat patients and, while augmentation of an antipsychotic with mood stabilizers is frequently needed, antipsychotic polypharmacy should be exceptional.

Clozapine prescribing in the UK: views and experience of consultant psychiatrists

OBJECTIVES

It has been repeatedly shown that clozapine is underutilized and there is delayed use of it in clinical practice.

METHOD

An online survey was sent to 2771 consultant psychiatrists registered with the Royal College of Psychiatrists in the UK. A total of 243 responded to this survey. The survey elicited their views and experiences in using clozapine as well as to identify what may be the underlying causes for its underutilization.

RESULTS

Over 75% acknowledged that they had good training in using clozapine and about 56% had clozapine-dedicated service. However, 40.5% preferred to use several other antipsychotics prior to considering clozapine. A third felt it was not safe to start clozapine in the community and 42% had less than five patients on clozapine. Eleven possible reasons for clozapine underutilization were identified including concerns about side effects, patients not wanting to have blood tests and lack of experience or knowledge. Knowledge deficiency in certain aspects of clozapine use were identified, e.g. a third of respondents did not know that the risk of agranulocytosis changes with time, 42.7% did not think that clozapine can reduce substance use, while 20% were not aware of its benefit in reducing suicidal risk.

CONCLUSIONS

Important areas of concern such as managing side effects and deficiency in evidence-based use of clozapine were identified. These can be targeted in training and professional development programme.

Efficacy and safety of aripiprazole augmentation of clozapine in schizophrenia: a systematic review and meta-analysis of randomized-controlled trials

Limited options are available for clozapine-resistant schizophrenia and intolerable side effects of clozapine. We conducted a systematic review of randomized-controlled trials (RCTs) to determine the efficacy and safety of aripiprazole augmentation of clozapine for schizophrenia. Electronic databases searched included PubMed, Scopus, Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Web of Science. This review synthesized the data of four short-term (8-24 weeks), placebo-controlled trials (N = 347). The overall relative risk (RR, 95% confidence interval) of discontinuation rates was not significantly different between groups (RR = 1.41, 95% CI = 0.78 to 2.56). The pooled standardized mean differences (SMDs, 95% CIs) (Z-test; number of study; I(2)-index) suggested trends of aripiprazole augmentation benefits on overall psychotic [-0.40 (-0.87 to 0.07) (n = 3; Z = 1.68, p = 0.09; I(2) = 68%)], positive [-1.05 (-2.39 to 0.29) (n = 3; Z = 1.54, p = 0.12; I(2) = 94%)], and negative [-0.36 (-0.77 to 0.05) (n = 3; Z = 1.74, p = 0.08; I(2) = 54%)] symptoms. Despite of no benefit on three cardiometabolic indices (i.e., fasting plasma glucose, triglyceride, and high-density lipoprotein), aripiprazole augmentation was superior for weight change with a mean difference (95% CI) of -1.36 kg (-2.35 to -0.36) (n = 3; Z = 2.67, p = 0.008; I(2) = 39%) and LDL-cholesterol with a mean difference of -11.06 mg/dL (-18.25 to -3.87) (n = 3; Z = 3.02, p = 0.003; I(2) = 31%). Aripiprazole augmentation was not correlated with headache and insomnia but significantly associated with agitation/akathesia (RR = 7.59, 95% CI = 1.43 to 40.18) (n = 3; Z = 2.38, p = 0.02; I(2) = 0%) and anxiety (RR = 2.70, 95% CI = 1.02 to 7.15) (n = 1; Z = 2.00, p = 0.05). The limited short-term data suggested that aripiprazole augmentation of clozapine can minimize the cardiometabolic risk, causes agitation/akathesia, and may be effective in attenuating psychotic symptoms.

Clozapine use pattern in persons with and without treatment for Parkinson's disease in real-world conditions: a naturalistic study in a community-based sample

OBJECTIVE

To explore the pattern of clozapine use in persons with severe mental illness and in persons with Parkinson's disease and the characteristics associated with early discontinuation in naturalistic conditions.

METHOD

A historical fixed cohort study of persons newly treated with clozapine was performed on a representative community-based sample of persons affiliated to the French health insurance system (n = 611,393). Treatment for Parkinson's disease was used as a proxy for this condition and lack of such treatment as a proxy for severe mental illness (SMI).

RESULTS

The prevalences of antipsychotic and clozapine use were 4.4% and <0.1% respectively. Of the 237 persons with a new outpatient prescription of clozapine, 25% were prescribed an antiparkinsonian treatment. In persons with SMI, the median duration of the index episode of clozapine treatment was 4.9 months (Interquartile range 1.0-20.5). Longer duration was independently associated with coprescription of anxiolytics or antidepressant. Few new additions of antipsychotics were observed during the clozapine episode.

CONCLUSION

Efforts have to be made to optimize clozapine treatment in real-world conditions. Considering the high frequency of persons with Parkinson's disease among clozapine users, further studies have to be performed in this population.