Differences between counties in the prescribing of clozapine.

Background: Norwegian national guidelines recommend that clozapine be offered to patients with schizophrenia after two failed attempts with other antipsychotic drugs. One of the main objectives for the introduction of clinical pathways in mental health care is to provide an equal service to patients irrespective of where in the country they live. We wished to investigate the prescribing level of clozapine in various Norwegian counties.
Material and Method: We retrieved aggregated data from the Norwegian Prescription Database, the Norwegian Patient Registry and Statistics Norway on prescribing of clozapine, number of patients in contact with the specialist health service with the diagnosis schizophrenia, and population figures for 2016.
Results: Nationwide in 2016, there were 50 users of clozapine per 100 000 inhabitants (95 % confidence interval (CI) 48-52). The number of users was highest in Troms county (76 (95 % CI 63-89) per 100 000 inhabitants) and lowest in Akershus county (38 (95 % CI 33-43) per 100 000 inhabitants). We found no significant correlation between the prescribing rate for clozapine and the proportion of the population in the county who were undergoing treatment for schizophrenia in the specialist health service.
Interpretation: Prescribing of clozapine varies among Norwegian counties and is not correlated with the proportion of the population who are undergoing treatment for schizophrenia in the specialist health service. Different levels of implementation of the national guidelines constitute a possible explanation for the geographic differences.