质量调整寿命年（Quality-adjusted life years, QALYs）是一种调整的期望寿命，用于评价和比较健康干预。 由于健康损害、伤残和（或）出生缺陷等原因造成的慢性疾病可以通过健康调查，医院出院纪录等资料进行评价。在实际应用时，反映剩余伤残严重性的权重可以通过患者或职业医师的判断来确定。

如果健康的生活了一年则记为1; 如果死亡则记为0; 如果是伤残则根据适当的标准记为0~1之间的数字。

如果经过诊断，认为一位患者可以以现在有疾病的状态生存10年。 假设这位患者可以选择完全健康但是生存的时间将会减少为8年，则该患者今后10年将被认为是8个质量调整寿命年（QALYs）。

The quality-adjusted life year or quality-adjusted life-year (QALY) is a generic measure of disease burden, including both the quality and the quantity of life lived. It is used in economic evaluation to assess the value for money of medical interventions. One QALY equates to one year in perfect health. If an individual's health is below this maximum, QALYs are accrued at a rate of less than 1 per year. To be dead is associated with 0 QALYs, and in some circumstances it is possible to accrue negative QALYs to reflect health states deemed 'worse than dead'.