Tunnel Vision Tu n n e l Vi s i o n The Economic Impact of Primary Open Angle Glaucoma - The Economic Impact of Primary OpenAngle Glaucoma - A Dynamic Economic Model A Dynamic Economic Model Centre for Eye Research Australia Centre for Eye Research Australia Acknowledgments and Disclaimer 11. References This report was prepared jointly by the Centre Weih L, Van Newkirk M, McCarty C, Taylor H (1998) “Patterns of glaucoma medication use in for Eye Research Australia and Access Economics urban and rural Victoria” Australian and New Zealand Journal of Ophthalmology, 26[Suppl]: Pty Limited. S12 S15. We acknowledge particularly the expert input Weinand F, Althen F (2006) “Long term clinical results of SLT in the treatment of POAG” Eur J and prior research of Ophthalmology, 16: 100-4. Professor Hugh Taylor AC Weinreb RN, Khaw PT (2004) “Primary open-angle glaucoma” The Lancet, 363: 1711-20. 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Centre for Eye Research Australia Tunnel Vision The Economic Impact of Primary Open Angle Glaucoma - A Dynamic Economic Model 105 Main heading toContents go here EXECUTIVE SUMMARY 7 1. Background 10 2. Primary Open Angle Glaucoma 11 3. Risk Factors 13 3.1 Intraocular pressure 13 3.2 Age 15 3.3 Cup-to-disc ratio 16 3.4 Central corneal thickness 16 3.5 Family history and genetics 17 3.6 Ethnicity 17 3.7 Diabetes mellitus 18 3.8 Other potential risk factors 19 4. Epidemiology 20 4.1 Definition of disease stage 20 4.2 Remission 20 4.3 Mortality 20 4.4 Population 21 4.5 Progression 21 4.6 Prevalence and incidence 29 4.7 Disease stages defined 33 5. Treatment 34 5.1 Medication 34 5.2 Laser treatment 39 5.3 Conventional surgery (trabeculectomy) 41 5.4 Prevalence estimates for each treatment group 43 5.5 Treatment efficacy 44 5.6 Side effects 50 6. Disease Costs 55 6.1 Discount rates 55 6.2 The cost to quality of life and wellbeing 56 6.3 Health system costs 60 6.4 Indirect costs 68 6.5 Deadweight losses 69 7. Summary of Model Parameters 70 8. The Model 73 9. Intervention Scenarios 76 9.1 The base case 76 9.2 Improved diagnosis rate 80 9.3 Change in the treatment protocol (Primary laser) 83 9.4 Research and development 87 9.5 Combinations 89 The Economic Impact of Primary Open Angle Glaucoma - A Dynamic Economic Model 1 Contents 10. Appendix 1: Meta-Analysis - Falls and Hip Fractures 92 10.1 Fixed-effects versus random-effects 92 10.2 Heterogeneity 92 10.3 Forest plots 93 10.4 Publication bias 96 10.5 Additional supportive literature 97 11. References 98 Figures Figure 1.1: Peripheral visual field loss in POAG 10 Figure 2.1: The glaucoma continuum 11 Figure 2.2: Healthy optic nerve 12 Figure 2.3 Glaucomorous optic nerve 12 Figure 3.1: Goldmen tonometery 14 Figure 3.2: Demographic distribution of glaucoma, Australians over 40 15 Figure 3.3: Cup-To-Disk ratio 16 Figure 3.4: Corneal thickness 17 Figure 3.5: Pseudoexfoliation pupil margin 19 Figure 4.1: Schematic of the level of impairment for definite glaucoma 29 Figure 4.2: Original prevalence rates 30 Figure 4.3: Smoothed prevalence rates (moving average across three age groups) 31 Figure 5.1: Glaucoma medication dispensed by year and type of script (% of total scripts) 35 Figure 5.2: MBS Trabeculoplasty Procedures, 1994-2005 40 Figure 5.3: Trabeculectomy 41 Figure 5.4: MBS Total of Trabeculectomy Procedures, 1994-2005 42 Figure 8.1: Main Menu 73 Figure 8.2: Options Sheet 74 Figure 8.3: Model Design 75 Figure 9.1: Prevalence OHT and POAG, base case 77 Figure 9.2: Value burden of disease due to POAG ($m), base case 78 Figure 9.3: Impact of increased diagnosis rates on DALYs(a) 82 Figure 9.4: Impacts of increased diagnosis rates on treatment costs 82 Figure 9.5: Cost Effectiveness Plane - Increase Diagnosis Rate(a) 83 Figure 9.6: Cost-savings resulting from a protocol change(a) 85 Figure 9.7: Burden of Disease 85 Figure 9.8: Decline in DALYs from new efficacious treatment 88 2 Centre for Eye Research Australia Tunnel Vision Main heading toContents go here Figure 9.9: Treatment costs with new treatment costing $1000 per person per year 88 Figure 9.10: Reduction in DALYs, combined interventions 90 Figure 9.11: Treatment costs, combined interventions 91 Figure 9.12: Total costs, combined scenarios 91 Figure 9.13: Cost effectiveness plane, Combined Scenarios(a) 91 Figure 10.1: Annotated Forest Plot (Random Effects Model) for Visual 94 Impairment and Falls Figure 10.2: Annotated Forest Plot (Random Effects Model) Glaucome/VFL and Falls 95 Figure 10.3: Annotated Forest Plot (Random Effects Model) for Visual Impairment and Hip Fractures 95 Tables Table 1.1: Disease stage 7 Table 3.1: Significant risk factors for OHT progression to glaucoma, identified by the OHTS 14 Table 3.2: Hazard ratios for development of POAG from OHT 14 Table 3.3: Risk factors for glaucoma progression, identified by the early manifest glaucoma trial 15 Table 3.4: Association Between Diabetes Mellitus and Glaucoma 19 Table 4.1: Relative risk of mortality by stage of Visual Impairment 21 Table 4.2: Natural progression rates (cumulative probability) 15 year period 25 Table 4.3: Estimates of disease progression in untreated patients 27 Table 4.4: Definitions of level of impairment for definite glaucoma 29 Table 4.5: OHT and Glaucoma prevalence rates 30 Table 4.6: Incidence and prevalence of ocular hypertension (% of age group) 32 Table 4.7: Proportion of people with glaucoma by age and severity (%), smoothed (moving average across three age groups) 32 Table 4.8: Disease Stage 33 Table 5.1: IOP lowering medications 35 Table 5.2: Proportion of each drug class by state, 2005 36 Table 5.3: Number of medications taken in combination 37 Table 5.4: Trabeculectomy - MBS services processed by jurisdiction by year 42 Table 5.5: Incidence and treatment failure rate for each stage of treatment from dismod II 44 Table 5.6: Progression rates (cumulative probability) in treated patients (15 year period) 46 Table 5.7: Studies of the efficacy of laser treatment 47 Table 5.8: Success rates for trabeculectomy 49 Table 5.9: Medication side effects 50 Table 5.10: Risk of COPD (% of Population), 2001 51 Table 5.11: Health System Cost of COPD ($ per Person), 2005 52 The Economic Impact of Primary Open Angle Glaucoma - A Dynamic Economic Model 3 Contents Table 5.12: Trabeculectomy Side-Effects 53 Table 5.13: Prevalence of Cataract (% of Population) 54 Table 5.14: Health System Cost of Cataract ($ per Person), 2005 54 Table 6.1: AIHW Disability Weightings 59 Table 6.2: Health Costs by Who Bears the Cost, 2004-05 60 Table 6.3: Cost of Medication per Person per Annum 61 Table 6.4: Total Cost of Trabeculoplasty Per Treatment 61 Table 6.5: Total Cost of Trabeculectomy Per Treatment 62 Table 6.6: Probability of Residing in an Aged Care facility, 2004-05 63 Table 6.7: Increased Risk of Falls From Visual impairment 64 Table 6.8: Meta-Analysis, Falls (Random Effects Model) 64 Table 6.9: Relative Risk of an accidental fall by Severity 65 Table