A new study by Kanter et al published in the Orphanet Journal of Rare Disorders examined cost-effectiveness of enzyme replacement therapy (ERT) in patients with infantile Pompe disease.
Pompe disease is an autosomal recessive disorder caused by a deficiency of lysosomal acid alpha-glucosidase leading to glycogen accumulation in multiple tissue types, mostly muscle (skeletal, cardiac, and smooth). Infantile Pompe disease is the most severe form of the disease.
The Dutch-based study compared the costs and quality of life of infants who received ERT [Myozyme (alglucosidase alfa)] to those who did not. Since infantile Pompe disease is a very serious and fatal condition, the results are difficult to interpret given that the life expectancy of infants not given Myozyme is less than 6 months while those given the ERT are expected to live well into their teens or longer. How do you really put a cost on that significant a difference? To address that question, the study looked at the cost-effectiveness expressed in incremental cost per quality-adjusted life year (QALY) gained and incremental cost per life year gained.
Survival for the non ERT cohort was obtained from two international studies on the natural course of infantile Pompe disease (n = 172; Kishnani, 2006) and 119 cases from the literature (Van den Hout, 2003). Survival for the ERT cohort was obtained from three sources; a trial extension study (n = 18; Kishnani, 2009), an international open-label study (n = 21; Nicolino, 2009) and data from Dutch infantile patients under treatment at Erasmus MC (n = 20).
Costs were calculated from a societal perspective. Total costs for patients treated with Myozyme consisted of four components: the cost of the drug, infusion-related costs, costs related to other health care use and informal care costs. Patients receiving standard therapy did not incur costs of the drug and infusion-related costs. Costs were expressed in 2009 euro values.
Cost-effectiveness was expressed in incremental cost per QALY gained and incremental cost per life year gained.
Survival. Figure 1 shows the survival curves in the two cohorts. In patients not receiving ERT (labeled ST in the figure), the mean life expectancy was 0.4 yrs. In infants receiving Myozyme, the mean life expectancy is 14 years but it should be noted that after the age of 5, no deaths were observed in the Myozyme treated group.
Lifetime incremental QALYs were estimated to be 7.00 in the Myozyme treated group compared to only 0.24 in the standard treatment group.
Costs. The table below shows the differences in the two treatments to be over 7 million euros with most of the costs being for the drug itself.
The incremental costs per QALY were estimated to be 1.0 million euros and the incremental cost per life year gained was estimated to be 0.5 million euros.
In their conclusion, the authors noted “The incremental costs per QALY ratio is far above the conventional threshold values.”
In the United States, the threshold is in the range of $30,000 - 50,000 per QALY.
Kanter TA, Hoogenboom-Plug I, rutten-Van Molken M, et al. Cost-effectiveness of enzyme replacement therapy with alglucosidase alfa in classic-infantile patients with Pompe disease. Orphanet J Rare Dis. 2014; 9:75 doi:10.1186/1750-1172-9-75
Kishnani PS, Hwu WL, Mandel H, et al. A retrospective, multinational, multicenter study on the natural history of infantile-onset Pompe disease. J Pediatr. 2006; 148:671–676.
Van den Hout HMP, Hop W, Van Diggelen OP, et al. The natural course of infantile Pompe’s disease: 20 original cases compared with133 cases from the literature. Pediatrics 2003;112:332–340.
Kishnani PS, Corzo D, Leslie ND, et al. Early treatment with alglucosidase alfa prolongs long-term survival of infants with Pompe disease. Pediatr Res. 2009; 66:329–335.
Nicolino M, Byrne B, Wraith JE, et al. Clinical outcomes after long-term treatment with alglucosidase alfa in infants and children with advanced Pompe disease. Genet Med. 2009;11:210–219.
Tables and figures courtesy of the open source journal, Orphanet Journal of Rare Disorders.