Continuation of clozapine treatment: practice makes perfect

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.

An evaluation of the variation and underuse of clozapine in the United Kingdom

BACKGROUND

Clozapine is the only licensed treatment for treatment refractory schizophrenia. Despite this, it remains grossly underused relative to the prevalence of refractory schizophrenia. The extent of underuse and the degree of regional variation in prescribing in the United Kingdom is unknown. It is also unclear, how the UK compares with other European countries in rates of clozapine prescribing.

METHODS

We obtained data relating to all clozapine prescribing in the UK from the relevant clozapine registries. We examined regional variation in clozapine use across England, corrected for the known prevalence of severe mental illness (SMI). We also compared the UK rate of clozapine use per 100,000 population to that described in other European countries.

FINDINGS

There is substantial variation in clozapine prescribing across different regions of England and only about a third of potentially eligible patients were prescribed the drug in the UK. Clozapine prescribing rate in the UK was lower than in several European countries.

INTERPRETATION

There is clear regional inequity in access to the most effective treatment in refractory schizophrenia in England. Strategies to increase clozapine use, by overcoming both real and perceived barriers, are urgently necessary to reduce treatment inequity for patients with refractory schizophrenia.

Prescriber and institutional barriers and facilitators of clozapine use: A systematic review

BACKGROUND

As clozapine is under-prescribed in persons with treatment-resistant schizophrenia (TRS), it is necessary to better identify the determinants of health inequalities in access to clozapine use.

OBJECTIVE

To identify mental health professionals' characteristics or attitudes and institutional characteristics facilitating or limiting clozapine prescribing.

METHOD

We systematically searched multiple electronic databases for articles reporting: (i) mental health professionals' attitudes and characteristics favoring or limiting clozapine prescribing; (ii) institutional characteristics associated with variations in clozapine prescribing; (iii) interventions aimed at enhancing clozapine prescribing. Data were synthesized narratively.

RESULTS

A total of 31 articles reporting findings of 29 studies published from 1993 to 2017 in 11 countries fulfilled our inclusion criteria. The main prescriber-related barriers to clozapine prescribing are lack of personal prescribing experience and concern with pharmacological characteristics of clozapine (blood monitoring and adverse effects). Lack of knowledge about the effectiveness of clozapine does not appear as a major determinant of under-prescription. Institutional-related characteristics favoring clozapine prescribing are prescribers' adherence to evidence-based medicine principles and learning by modelling from experienced clozapine prescribers.

CONCLUSION

Effective strategies to increase access to clozapine in persons with TRS include implementation of integrated clozapine clinics, simplification of blood monitoring, education for prescribers and contact with experienced prescribers. Programs addressing barriers in clozapine prescription need to be disseminated more broadly to ensure persons with TRS have access to evidenced based treatments such as clozapine. Inequality in access to clozapine care should be more systematically handled by mental health facilities and health regulatory agencies.

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.

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.