Cost of care comparison between cerebral palsy patients treated with botulinum toxin type A and propensity score-matched controls

Abstract

SummaryThis analysis compared children with cerebral palsy treated with botulinum toxin type A (BTX-A) versus those not treated with BTX-A to assess the total cost of care and utilisation in a state run Medicaid program in the United States. A retrospective pre/post design was used with nested case-control matching based on propensity scores. Data for the study were extracted from the paid claims for South Carolina Medicaid recipients from 1995 through 2001. Extracted variables included cost of services, procedures performed and diagnoses. It was hypothesised that BTX-A use would not increase the total cost of care but would be related to cerebral palsy diagnosis (e.g. diplegia, hemiplegia, quadriplegia) when demographic covariates (age, race, gender), comorbid conditions (analgesic use, scoliosis, hydrocephalus, hip dysplasia, mental retardation, seizures) and hospitalisations were controlled. Conditional logistic regression via a Cox regression model was used to estimate the relationship between BTX-A use and the aforementioned variables. A total of 2,364 patients met the study inclusion and exclusion criteria. After 1:6 matching, a total of 406 patients were used in the analyses (58 cases and 348 matched controls). After matching, no significant differences were noted between the groups on any of the study variables. Regression results indicated that cerebral palsy diagnosis, but not cost, was significantly related to BTX-A treatment. The cerebral palsy categories of diplegia (β=2.55; hazard ratio [HR]=5.91), hemiplegia (β=5.43; HR=23.88) and quadriplegia (β=4.23; HR=10.22) were all significant in the model (p < 0.01). The mean 2-year cost of treatment for BTX-A users (in US$) was $44,761 (sd $56,643) versus $41,553 (sd $57,844) for non-BTX-A users. These results indicate that, over the 24 months studied, BTX-A did not add to the total cost of care. Whilst the number of subjects is small, it represents the entire population of cerebral palsy patients treated over the study period.