[Report: clozapine blood level testing by immunoassay]

Dubé A, Muradqadam K, Rivard J
Record ID 32018013795
French
Original Title: Dosage sanguin de la clozapine par test immunologique
Authors' objectives: A request to introduce a new test into the Répertoire québécois et système de mesure des procédures de biologie médicale (hereinafter referred to as the Répertoire) was submitted to the Ministère de la Santé et des Services sociaux (MSSS) by the Grappe Montréal - CHUM (Centre hospitalier de l'Université de Montréal), hereinafter referred to as the requesting laboratory. The MSSS has mandated the Institut national d'excellence en santé et en services sociaux (INESSS) to evaluate the relevance of including an immunological assay in the Répertoire for the clozapine blood level testing used in the therapeutic follow-up of patients treated with this antipsychotic.
Authors' results and conclusions: RESULTS (#1 POPULATION DIMENSION): Schizophrenia is a chronic, disabling illness for which there is currently no cure. Clozapine is an antipsychotic primarily used in the treatment of people with schizophrenia spectrum disorders and other psychotic disorders. The clozapine TDM allows clinicians to adjust drug therapy for any patient receiving clozapine to control symptoms, minimize adverse effects and reduce the risk of relapse. However, to reap the expected benefits of clozapine TDM, test results should be obtained within a short timeframe. (#2 CLINICAL DIMENSION ): To be clinically useful, clozapine TDM results must be available for decision-making in a timely manner. A response time (from sample collection to transmission of results) of 24 hours is desirable. However, a response time of 48 hours is considered adequate in most cases, except when intoxication is suspected, where a result within a few hours is required. The clinicians consulted believe that timely results would ultimately reduce the duration and severity of adverse events, and possibly the length of hospital stays. (#3 ORGANIZATIONAL DIMENSION): Regional deployment of clozapine blood level testing by immunoassay would shorten response times. Implementation on automated lines, as proposed by the requesting laboratory, would facilitate sample management by eliminating transportation and handling steps, as well as manual data entry. Timely response would enable results to be used in a variety of clinical situations, including emergencies, which is currently impossible for requests from facilities not served by the Grappe de la Capitale-Nationale. (#4 SOCIO-CULTURAL DIMENSION): The learned societies recommend clozapine TDM, as a complement to clinical judgment, as a tool to optimize the management of patients receiving clozapine. They also recommend that TDM results be made available in a timely manner. (#5 ECONOMIC DIMENSION): The weighted value for this analysis is 24.97. The scientific literature provides no guidance on the cost-effectiveness of clozapine TDM by immunoassay. Nevertheless, compared with chromatography, it would be efficient since its weighted value and response time are lower. Compared with no test, although its efficiency is not measurable with available data, it has the potential to reduce the use of medical resources and provide benefits for the patient.
Authors' recommendations: Based on the above findings, the INESSS recommends the introduction of the clozapine blood level testing by immunoassay to the Répertoire, given that: • The proposed method is a valid and complementary option to the current testing offer; • For TDM requests, response time (from sample collection to transmission of results) should be around 48 hours. For urgent requests, a response time of a few hours is desirable; • A regional designation would eliminate delays related to sample transportation and provide timely testing; • The advantages of automated testing are desirable given the current staff shortage. • The test will have to meet ISO 15189 requirements. • Access to chromatographic clozapine and norclozapine testing should be maintained.
Authors' methods: The evaluation approach included a review of the scientific literature, a grey literature search and consultations with clinicians and other stakeholders. A review of the economic literature was conducted on the cost-effectiveness of clozapine immunoassay. A budgetary impact analysis considering the costs associated with the introduction of this assay to the Répertoire was conducted. Costs were projected over a 3-year timeframe from a healthcare system perspective. All scientific, contextual and experiential data were interpreted and synthesized in findings to guide the analysis process for the development of the recommendation.
Details
Project Status: Completed
Year Published: 2024
English language abstract: An English language summary is available
Publication Type: Full HTA
Country: Canada
Province: Quebec
MeSH Terms
  • Schizophrenia
  • Clozapine
  • Antipsychotic Agents
  • Drug Monitoring
  • Psychotic Disorders
  • Schizophrenia Spectrum and Other Psychotic Disorders
Contact
Organisation Name: Institut national d'excellence en sante et en services sociaux
Contact Address: L'Institut national d'excellence en sante et en services sociaux (INESSS) , 2021, avenue Union, bureau 10.083, Montreal, Quebec, Canada, H3A 2S9;Tel: 1+514-873-2563, Fax: 1+514-873-1369
Contact Name: demande@inesss.qc.ca
Contact Email: demande@inesss.qc.ca
Copyright: L'Institut national d'excellence en sante et en services sociaux (INESSS)
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