Utilities measures quality of life (QoL) in three to eight different health domains with an economic and management decision-making foci, and typically produce a rating of a health state’s relative preferability with, as extremes, death (a utility of 0.00) and perfect health (a utility of 1.00). The value of the states between 0.00 and 1.00 is determined by the average of the values assigned to them by community samples, and are derived from one of several available techniques to develop ratings on a ratio scale, which include time trade-off, standard gamble, and direct rating. Two common type of scores produced include:
Disability-Adjusted Life Years (DALYS): DALYs are an overall measure of disease burden. DALYs are calculated by combining utilities with time (years) spent living with a disability (YLD) and years of life lost (YLL; DALY = YLL + YLD), and they have been used to evaluate the benefits of a given intervention/health program.
Quality-Adjusted Life Years (QALYS): QALYs are designed to aggregate in a single summary measure the total health improvement for a group of individuals, capturing improvements from impacts on both quantity of life and QoL — with QoL broadly defined. QALYs are calculated by the change in utility value induced by the treatment and is multiplied by the duration of the treatment effect to provide the number of QALYs gained.
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