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Difference Between DALY and QALY


DALY and QALY are both measurements used in order to calculate time (in terms of life years) of an individual or a general population. The concept of time, illnesses, diseases, and health treatments are major and recurring factors in both methods of measurement. A common factor between the two measurements is that both serve as evaluations, and both are under cost utility analysis. They also share a common technique of weighing the cost per healthy unit measure.

“DALY” stands for “disability adjusted life years” while the acronym “QALY” stands for “quality adjusted life years.”

DALY, in essence, measures health loss in the quality of life. On the other hand, QALY measures the same quality of life in health gain. QALY is usually used in measuring the quality and quantity of care and life when considering options for health treatments for a particular illness.

In measurements, both DALY and QALY only produce a single number (either 1 or 0) to express death or perfect health in the extension of describing the quality and quantity of health.

QALY was developed earlier than DALY. After 20 years, DALY was developed by Harvard University in 1900. A decade later, it was adopted by the World Health Organization (WHO).

QALY measures the burden of disease on a life with the inclusion of quality and quantity of lived life. It is a method of evaluation that offers information in considering, measuring, and choosing health interventions often in the role of disease treatment. It generates an estimated number of years that can be added to a life if an intervention is given.

Another field that it considers is the financial costs of the medical intervention.
Factors in measuring the quality of life that are to considered in QALY are: degree of pain, mobility, and general mood.

QALY is expressed in either 1.0 or 0.0. The designation “1.0” represents a perfect health year while “0.0” represents death.

Factors in QALY include:Time trade-off (TTO), Visual Analog Scale (VAS), and Standard Gamble (SG).

In contrast, DALY measures mortality and mobility. In a sense, it is a modified version of QALY. It deals with the years lost due to the poor quality of life due to illness and disability or any non-lethal heath problem or lifetime lost due to an early death.

DALY places consideration on disability, discounting, and age. DALY is expressed by adding Years of Life Lost (YLL) and Years Lived with Disability (YLD). The measurement for death is expressed as “1” while “0” represents perfect health.


1.Quality adjusted life years and disability adjusted life years are both measurements to calculate the quality and quantity of life either of individuals or the general population. Both measurements use a single number of “1” or “0” to measure and represent either perfect health or death.
2.Both evaluations have different coverage and interpretations. Both also have validity and accuracy problems.
3.DALY is considered as a modified version of QALY. It was also developed more recently having a 20-year lapse since the invention of QALY.
4.QALY measures the burden of death while DALY measures mortality and morbidity. QALY also focuses on the importance of medical intervention in an illness or disability. It also compares treatment and possible financial costs of each treatment. On the other hand, DALY measures the lost years of a life due to disability or early death.
5.The use of a single number expression is also different in both measurements. In QALY, “1” is an indication of perfect health while in DALY it represents death. The other numeral, which is “0,” means perfect health in DALY and death in QALY.

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  1. WHO has been set up in 1948. Therefore they didnt adopted DALY a decade later 1900….

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