13.2. Assessing priorities through estimation of the burden of disease

13.2.1. Disability adjusted life years (DALYs)

In order to assess health priorities when planning policies to promote public health and optimal organization of health services to implement policies and effectively prevent and treat diseases, it is very important to quantify the health loss due to different diseases or underlying risk factors. The use of the Disability Adjusted Life Years (DALYs) makes various types of health effects and both diseases and mortality more directly comparable.

DALYs try to combine the years lost from premature mortality with the years spent with a disease, by using a weighting factor expressing the disability associated with a disease. For example, if a disease has a weighting factor of 0.5, this means that a year spent with this disease is considered equivalent to half a year lost due to premature death. In this way, the lost life years and the disease year equivalents are enumerated as DALYs. Lost DALYs can be calculated for various diseases using statistical information on mortality rates and incidences/prevalences/seriousness, and can also be calculated for the risk factors based on the fraction of one or more diseases which can be explained by that risk factor (or attributed to the risk factor). DALYs lost due to a particular cause (disease or risk factor) can also be understood in terms of gain which is, in theory, possible through optimum intervention.