Disability Weights for Visual Impairment and Blindness

1. Disability Weights for Visual Impairment and Blindness Jill Keeffe Centre for Eye Research Australia (CERA)

2. Terminology • Disability weights – 0 to 1 ratio scale • YLL and YLD • Disease • Health states • Activities • Participation • Well-being, quality of life

4. GBD Methods for DW • 1990 GBD disability classes for ADL • Eating and personal hygiene • ADL such as meal planning • procreation • Occupation • Education • Recreation • Panel of experts assigned weights deriving average weights

5. 1996 Revision • Person trade-off method • DALY • Suitable for adults but not replicable • Not sensitive to mild levels of health states

6. GBD 2000-2002 • Based on 1990 weights • Panel of experts • Proportion of time in a class • If weights not available results for Dutch or Australian studies used • Dutch study added health state distributions for sequelae from EQ-5D • Vision 4.2% of GBD; in top 7 diseases

8. New GBD • Diseases • Health states in 0 to 1 scale • Not utility, contribution to health and welfare, activities or participation • Departure from ideal health on ratio scale so makes comparison possible • Homogenous health experience

9. Disease • Dysfunctions of the body system • Discrete list under groups • Sense organs: glaucoma, cataracts, AMD, RE • CVD and Circulatory: Ophtalmianeonatorum, corneal scar in LBW children • Nutritional: VAD • NTD: onchocerciasis, trachoma • Diabetes: retinopathy

10. Health States • Core domains of body functions • Ambulation, cognition • Senses such as vision and hearing • Functional health domains, not well-being • GBD uses disability as a proxy for loss of health in the terminology YLD and DALY • “what can be seen”, ie vision loss, not performance

11. Disability Weight • Loss of health measured in decrements of health capacity • Quantification of the level severity of health of each domain – low vision or blindness • Average health state valuation across the entire distribution experienced by all individuals • Same across countries

12. YLD • For each case or sequela YLD = incidence, average duration until remission or death and average disability weight • Community survey of chronic health states • Checklist and cognitive interviews • Rating of health states • Surveys in 3 countries • Health professionals ranking and VA scale 0-1

13. Implications • Impact of vision on physical function can be quite limited • Corrected vision not loss of function • Use in cost effectiveness analysis

14. Global blindness by etiology Source: GBD 2010 Estimation Strategy Report for Vision Loss

15. Global Low Vision Loss by etiology Source: GBD 2010 Estimation Strategy Report for Vision Loss

16. Global prediction of blindness for females by etiology and age Source: GBD 2010 Estimation Strategy Report for Vision Loss

17. Global prediction from low vision for females by etiology and age Source: GBD 2010 Estimation Strategy Report for Vision Loss

18. Predicted number from blindness in North America males by etiology and age Source: GBD 2010 Estimation Strategy Report for Vision Loss

19. Blindness 1990 Source: GBD 2010 Estimation Strategy Report for Vision Loss

20. Blindness 2010 Source: GBD 2010 Estimation Strategy Report for Vision Loss

21. Near vision loss 2005 Source: GBD 2010 Estimation Strategy Report for Vision Loss

22. Low vision 2005 Source: GBD 2010 Estimation Strategy Report for Vision Loss

23. Blindness 2005 Source: GBD 2010 Estimation Strategy Report for Vision Loss