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Clozapine treatment and discontinuation in Iceland: A national longitudinal study using electronic patient records
Oddur Ingimarsson1,2, James H MacCabe3,4, Magnús Haraldsson1,2
1a Faculty of Medicine , School of Health Sciences, University of Iceland , Reykjavik , Iceland ;
Background:
Clozapine is the only drug approved for treatment-resistant schizophrenia. There is evidence that clozapine is underutilized.
Aims:
To evaluate the initiation and discontinuation of clozapine at Landspitali University Hospital in Iceland and the prevalence of antipsychotic polypharmacy in clozapine-treated patients.
Methods:
The study is a part of an ongoing longitudinal study of schizophrenia in Iceland. We identified 201 patients on clozapine or who have been on clozapine by using a keyword search in the electronic health records and by reviewing their medical records.
Results:
Mean age at first treatment with clozapine was 37.8 years. Mean follow-up period on clozapine was 11 years. After 20 years of treatment 71.2% of patients were still on clozapine. After one year of treatment 84.4% of patients were still receiving clozapine treatment. We estimate that 11.4% of patients with schizophrenia in Iceland are taking clozapine and that 16% have been treated with clozapine at some point. Polypharmacy is common, since nearly 2/3, 65.6%, of patients taking clozapine use at least one other antipsychotic and 16.9% are also receiving depot injections.
Conclusions:
We need to increase the awareness of psychiatrists in Iceland with regard to treatment with clozapine, since only about half of the estimated population of patients with treatment-resistant schizophrenia in Iceland have ever been treated with clozapine. Nearly two thirds of patients who are prescribed clozapine in Iceland remain on it long-term.
