disability weights for visual impairment and blindness jill keeffe centre for eye research australia...
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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