Preventing Glaucoma Progression using the Trabecular Micro-Bypass Implant IStent Inject®. A Cost-Effectiveness Analysis

Abstract

Objective: To assess the economic impact of reducing glaucoma progression by using the trabecular micro-bypass implant, iStent inject®, in the Reference Centers for glaucoma treatment within the Brazilian Public Unified Health System (SUS). Methods: In a cost-effectiveness analysis, a Markov model was developed, and the costs were obtained from the SUS perspective (medical direct costs). Effectiveness was measured in progression-free lifeyears. The time horizon was the mean life expectancy of the Brazilian population. The model parameters were obtained through a review and a critical analysis of the literature. The base case comprised a hypothetical cohort of patients with open-angle glaucoma, using anti-glaucoma eye drops and followed up at Reference Centers of SUS. We tested whether the incorporation of iStent inject® as an alternative second-line therapy would be cost-effective. The outcome measure was the incremental costeffectiveness ratio (R$/progression-free life-years). We tested the robustness of the model by univariate and probabilistic sensitivity analyses. Results: The use of iStent inject® led to decreased progression rate of glaucoma, evidenced by the amount of progression-free life-years obtained with each treatment strategy (7.82 progression-free life-years with iStent inject® versus 6.33 progression-free life-years with medical treatment), thereby improving glaucoma control. There was also a reduction in future costs associated with eye drops, filtering surgeries, and treatment complications. Incremental cost-effectiveness ratio ranged from R$ 6,429.30 to R$ 7,550.97/progression-free life-years. The model proved to be robust in the sensitivity analyses. Conclusion: This analysis showed that iStent inject®, when used after the failure of the first-line therapy, is able to reduce the rate of glaucoma progression at an acceptable cost.