3.1 Years of life lost, years lost due to disability, and healthy life expectancy

BOX 3.1

DALYs (45.2 percent due to disability and 54.8 percent due to life years lost). In 2020, Saudi Arabia lost an estimated 5,964,386 DALYs due to NCDs.1 This figure represents 65.2 percent of all DALYs (9,151,937), with 45.8 percent due to disability and 54.2 percent due to life years lost prematurely.

Cardiovascular diseases, cancers, and diabetes account for approximately one-third of the NCD burden. The eight major causes of disability and death are ischemic heart disease, stroke, type 2 diabetes, chronic obstructive pulmonary disease (COPD), breast cancer, colon cancer, stomach cancer, and lung cancer. Of these, ischemic heart disease and stroke are the top two contributors to NCDattributable DALYs (17.0 percent). These conditions affect both men and women and, more recently, even people as young as in their 40s.

Longer life expectancy and lower fertility rates are changing the age distribution of the country’s population. These changes are expected to exacerbate the overall burden of NCDs and the portion of DALYs attributable to them. The proportion of the population over 50 years of age is projected to increase more than twofold, from 15.1 percent of the total population in 2020 to 36.6 percent in 2050. In 2020, the top eight contributors to NCD-attributed DALYs constituted 25.9 percent of all NCD-attributed DALYs in the country. This proportion is expected to rise to 37.9 percent by 2050 as the population ages.

Much of the NCD burden due to these eight conditions can be reduced by modifications to smoking, diet, and exercise. Research over the last 50 years strongly supports the health benefits of reducing NCDs and of modifying behavior in these three key areas. Policy interventions aimed at reducing smoking and lowering salt consumption have been shown to produce lasting long-term effects (Brinsden et al. 2013; Kostova et al. 2014). In addition, the peer-reviewed literature has shown that policy interventions to modify BMI via exercise produce short-term effects (Mitchel et al. 2014).

This chapter calculates the health burden from NCDs in Saudi Arabia over the next 30 years by quantifying disability-adjusted life years lost due to NCDs from 2020 to 2050, calculating reductions in premature death and disability as a gain in healthy years lived (box 3.1), and applying several estimates of reductions

Years of life lost, years lost due to disability, and healthy life expectancy

Noncommunicable diseases (NCDs) cause not only premature death (years of life lost [YLLs]) but also disability (years lost due to disability [YLDs]). When summed, these two measures form the disabilityadjusted life year (DALY). This measure quantifies the health gap between an ideal health state—a theoretical state in which mortality is caused only by old age—and years of life spent disabled or injured and in subpar health due to disease. DALYs are often used as a basis for making health policies as well as for setting intervention priorities. The DALY is calculated as follows:

DALY = YLL + YLD. (B3.1.1)

Minimizing premature death and disability is the equivalent of maximizing healthy life years. Healthy life expectancy (HALe) is defined as the average years of life that a person can expect to live in “full health” (GBD 2017 DALYs and HALe Collaborators 2018). This summary measure is adjusted for years that are lived with disease and injury. HALe represents an intuitive way to think about reducing disability and premature mortality. These reductions can be interpreted as a gain in healthy years lived (or a gain in HALe):

HALE = ex 0 − YLD, where ex0 = life expectancy at birth. (B3.1.2)