Economic evaluation of different haematological monitoring schemes for patients with treatment-resistant schizophrenia using clozapine.

BACKGROUND

Clozapine is licensed for treatment-resistant schizophrenia (TRS). Because of the risk of clozapine-induced agranulocytosis, its use requires regular haematological monitoring. Substantive evidence supports revisions of absolute neutrophil counts (ANCs) for clozapine discontinuation and ceasing of indefinite haematological monitoring.

AIMS: To examine the cost-effectiveness and budget impact of different haematological monitoring schemes compared with the current UK monitoring practice for patients using clozapine.

METHOD: We performed a cost-effectiveness and budget impact analysis from the healthcare system perspective over a 3-year period, comparing the current UK clozapine monitoring practice with extended haematological monitoring and a revision of ANC criteria. Costs and quality-adjusted life years (QALYs) were estimated using a semi-Markov model that followed a simulated cohort of 100 000 adults with TRS. Sensitivity analyses were conducted.

RESULTS

Extended haematological monitoring would lead to lower mean total costs per patient (6388.34 v. 5569.77 GBP) and not compromise quality of life (in QALYs 795.83 v. 795.79 days). A revision of ANC criteria for clozapine discontinuation would not substantially lower costs (6388.34 v. 6390 GBP), but lead to a slight increase in QALYs (795.83 v. 797.08 days), through patients benefitting from longer clozapine treatment. A combination of extended haematological monitoring and revision of ANC criteria would be the dominant strategy, which means that costs are lower (6388.34 v. 5548.50 GBP) and QALYs slightly increase (795.83 v. 797.03 days) compared with the current UK monitoring practice.

CONCLUSIONS

A revision of current UK clozapine monitoring practice would be beneficial from both a clinical and an economic perspective. Adjusting ANC criteria for clozapine cessation avoids unnecessary early discontinuation of clozapine treatment and has a positive impact on quality of life. An extension of monitoring intervals reduces costs borne by the healthcare system. Safety is not compromised by these changes.