Differences between regional health authorities
Northern Norway Regional Health Authority differed from the other regional health authorities in several respects. They had by far the highest prescribing rate for clozapine, and prescribed it more frequently to younger patients and in smaller average doses when compared to the other regional health authorities. These figures are in apparent contradiction to the observation that Northern Norway Regional Health Authority has the lowest prescribing rate for antipsychotic drugs as a group.
One possible interpretation of these figures is that Northern Norway Regional Health Authority more frequently initiates the recommended drug-based therapy for treatment-resistant schizophrenia (clozapine) at an earlier stage and thus needs smaller doses, and secondary to this has a lower total use of antipsychotic drugs. It is important to emphasise, however, that no conclusions regarding treatment quality can be drawn on the basis of observational registry studies such as this one. Other possible explanations for the low average doses in Northern Norway Regional Health Authority could be that combination therapies involving multiple antipsychotic drugs are used more frequently, or that clozapine is used for other indications (for example Parkinson's disease, for which considerably smaller doses are recommended (19)). The low total prescribing rate of antipsychotic drugs as a group and the relatively low prescribing rate and large average dose of clozapine to the oldest patient groups in Northern Norway Regional Health Authority run counter to these explanations.
Figures from the regional health authorities show that the prescribing of clozapine reaches its peak later for women than for men. This could possibly be explained by the later debut of schizophrenia among women compared to men (20). Furthermore, the figures show that women are prescribed with clozapine more rarely than men. One explanation for this could be that schizophrenia in general (8), and possibly also treatment resistance (20), occur more rarely in women than in men. Determining whether these sex differences reflect a practice of prescribing clozapine more rarely to women, even when an indication of treatment-resistant schizophrenia has been established, will be an important topic for further research.
Geographical differences in the prescribing of clozapine have also been described in other countries (9, 21). The authors of these articles point to local variations in treatment practices as a key cause. Variations in psychiatrists' attitude to and knowledge about clozapine are likely to be an important element of this explanation (22). In light of the fact that clozapine is prescribed more rarely (9, 10, 21) and later (12) in the course of illness than what is recommended, one interpretation of the geographical differences shown in this study is that a proportion of the patients with treatment-resistant schizophrenia are not provided with optimal drug-based therapy.
Future research should seek to clarify the extent to which clinicians possess sufficient knowledge about clozapine to make this drug a real alternative for patients with treatment-resistant schizophrenia. A more consistent practice can be achieved by increasing the focus on identification of and interventions against treatment-resistant schizophrenia in the training of mental healthcare personnel.