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

Abstract

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. To examine the cost-effectiveness and budget impact of different haematological monitoring schemes compared with the current UK monitoring practice for patients using clozapine. 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. Extended haematological monitoring would lead to lower mean total costs per patient (6388.34 <i>v</i>. 5569.77 GBP) and not compromise quality of life (in QALYs 795.83 <i>v</i>. 795.79 days). A revision of ANC criteria for clozapine discontinuation would not substantially lower costs (6388.34 <i>v</i>. 6390 GBP), but lead to a slight increase in QALYs (795.83 <i>v</i>. 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 <i>v</i>. 5548.50 GBP) and QALYs slightly increase (795.83 <i>v</i>. 797.03 days) compared with the current UK monitoring practice. 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.