Disability and quality of life weights for vision impairment

Disability adjusted life years (DALYs) and Quality adjusted life Years (QALYS) are tools used internationally for assessing health care interventions and treatments. Both QALYs and DALYs combine the length of life with quality of life—QALYs are a measure of health expectancy and reflect the product of the years lived and health related quality of life whereas DALYs are a measure of burden of disease and reflect the sum of years of life lost due to premature mortality (mortality component) and years lived with disability (morbidity component).

Estimating DALYS and QALYS requires values for health states or specific conditions which are:

• disability weights for DALYS
• utility or quality-of-life weights for QALYs

These values quantify the societal perceived quality-of-life by measuring the preference for being in a particular health state. Both weights are measured on a scale of 0 to 1. For disability weights, 0 represents full health and 1 represents death. For quality of life weights, 1 represents full health and 0 represents death.

Several studies have shown that the different methods to derive disability weights and quality of life weights may lead to divergence between the DALYs and QALYS and therefore impact decision making.

Our work will summarise the methods that have been used to estimate disability weights and quality of life weights, analysing other available evidence to evaluate the weights of blindness and vision impairment, and providing recommendations to help design and develop disability and quality of life weights measurement studies in the future.