Disability Weights for Visual Impairment and Blindness

Jill KeeffeCentre for Eye Research Australia (CERA)

Terminology

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

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

1996 Revision

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

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

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

Disease

• Dysfunctions of the body system• Discrete list under groups• Sense organs: glaucoma, cataracts, AMD, RE• CVD and Circulatory: Ophtalmia neonatorum,

corneal scar in LBW children• Nutritional: VAD• NTD: onchocerciasis, trachoma• Diabetes: retinopathy

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

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

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

Implications

• Impact of vision on physical function can be quite limited

• Corrected vision not loss of function• Use in cost effectiveness analysis

Global blindness by etiology

Source: GBD 2010 Estimation Strategy Report for Vision Loss

Global Low Vision Loss by etiology

Source: GBD 2010 Estimation Strategy Report for Vision Loss

Global prediction of blindness for females by etiology and age

Source: GBD 2010 Estimation Strategy Report for Vision Loss

Global prediction from low vision for females by etiology and age

Source: GBD 2010 Estimation Strategy Report for Vision Loss

Predicted number from blindness in North America males by etiology and age

Source: GBD 2010 Estimation Strategy Report for Vision Loss

Blindness 1990

Source: GBD 2010 Estimation Strategy Report for Vision Loss

Blindness 2010

Source: GBD 2010 Estimation Strategy Report for Vision Loss

Near vision loss 2005

Source: GBD 2010 Estimation Strategy Report for Vision Loss

Low vision 2005

Source: GBD 2010 Estimation Strategy Report for Vision Loss

Blindness 2005

Source: GBD 2010 Estimation Strategy Report for Vision Loss