Botulinum toxin type A in the management of equinus in children with cerebral palsy: an evidence-based economic evaluation.

Abstract

The aim of this study was to compare two methods of conservative management of calf spasticity and equinus gait--intramuscular injection of botulinum toxin type A (BTX-A) and serial casting. An economic evaluation framework was adopted to assess whether BTX-A offers value for money in the management of equinus gait due to calf spasticity in children with cerebral palsy. Short- to medium-term health care costs and outcomes were estimated for the comparison. This study was embarked upon to provide clinical and economic data as part of an application to the Pharmaceutical Benefits Advisory Committee (PBAC) for the reimbursement of BOTOX by the Australian Commonwealth Government. This is the primary mechanism for reimbursement of pharmaceuticals in Australia, as they are not routinely reimbursed through health insurance companies. The perspective of the analysis was that of the Australian health system. Randomized controlled trials (RCTs) exist comparing one treatment cycle of BTX-A with serial casting (Corry et al., 1998; Flett et al., 1999). A long-term prospective study provided data on multiple cycles of BTX-A treatment in a more naturalistic setting (Boyd et al., 1999). A simple economic modelling approach was used to establish resource utilization by treatment arm. Only direct medical costs were considered (BTX-A, medical personnel time and medical consumables). Clinical efficacy was obtained from the randomized controlled trials (Corry et al., 1998; Flett et al., 1999). Patient/parent preference was obtained from long-term follow-up (Corry et al., 1998) and a preference questionnaire (Flett et al., 1999). Australian treatment patterns and patient demographics were obtained from the naturalistic study (Boyd et al., 1999). The RCTs demonstrated equivalent efficacy of BTX-A and serial casting; however, with BTX-A the effect lasted longer and was clearly the preferred treatment. For patients with hemiplegia the costs of an episode of treatment with BTX-A or serial casting are ($AUD) $595 and $435, respectively, and thus the additional costs associated with BTX-A are $160. The corresponding costs for patients with diplegia are $1045 for BTX-A treatment and $870 for serial casting and thus the additional cost associated with BTX-A is $175. With an overall treatment duration of 3.7 years and an average treatment interval of 10 months, patients would receive an average of 5.4 treatments. Thus, for patients with hemiplegia the total additional cost, discounted at 5% annually, for BTX-A is $793. For patients with diplegia the total additional cost for BTX-A is $867. CONCLUSIONS AND CLINICAL INTERPRETATIONS: BTX-A is an effective, safe and acceptable treatment modality and is associated with only a modest increase in direct medical costs per child per year. BTX-A can be considered a valuable and cost-effective treatment in the conservative management of equinus due to calf spasticity in children with cerebral palsy. This conclusion is supported by the acceptance of the Pharmaceutical Benefits Advisory Committee (PBAC) recommendation that BOTOX should attract a full Government subsidy in Australia.