Lifetime Costs and QALYs for POAG patients,early stage versus moderate stage treatment:A Preliminary Discrete Event Simulation cohort study

Abstract

Purpose : To compare the lifetime costs and quality-adjusted life years(QALYs)of primary open-angle glaucoma(POAG)patients commencing treatment at early (mild) and moderate stages in Singapore

Methods : The model was structured as a patient-level discrete event simulation, based on the van Gestel et.al.’s model(2012) which tracked the natural course of POAG.POAG was defined as glaucomatous optic neuropathy with compatible visual field loss.Stages of POAG were defined as per the mean deviation values on automated perimetry viz.mild(early)≥-6dB,moderate<-6dB to -12dB,and severe ≤-12dB.Life time costs included direct costs(consultation,medication,laser,surgical,hospitalization,and low vision care costs).QALYs were assessed using the Health Utility Index Mark3(HUI3).Data parameters were estimated from a Singapore POAG cohort where possible;otherwise literature estimates were used.Validation was performed based on outputs with the cohort data.Heterogeneous cohorts of 3000 patients were simulated; and lifetime costs and QALYs were accumulated.Probabilistic sensitivity analysis was used to estimate confidence ranges(CR).Sensitivity analysis was performed to account for a presumed 10-year lead-time bias for individuals with mild disease,and the possibility that due to selection bias the moderate cohort had more severe disease(adjusted by increasing the hazard ratio for worsening disease in the mild cohort to1.03)

Results : Patients with initial early POAG and who progressed to moderate stage had higher lifetime QALYs(1.51=19.7 95%CR 19.7-19.77compared to those who were initially moderate and progressed -18.22;95%CR 18.2-18.26).There was a similar pattern of lower costs for initial early POAG (S$-14,941=S$33,960;95%CR 33,866-34,054 compared to those who commenced treatment at a moderate stage -S$48,901;95%CR 48,789-49,012).The trend for lower lifetime costs and higher QALYs remained even after sensitivity analysis(Table).Cost and QALYs for baseline and sensitivity results are shown graphically(Figure)

Conclusions : Early treatment of POAG appears to have lower life time costs and higher QALYs compared to initiating treatment at a moderate stage.Our data suggest that early treatment is cost effective,perhaps even economically dominant;however,we cannot exclude the possibility that individuals with moderate POAG at onset of treatment have a more aggressive and costly disease

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.