Methods

increasing overweight/obesity prevalence. Additionally, low intake of fruits and vegetables and low physical activity are modeled as separate modifiable risk factors, and their impact on the NCD burden in Saudi Arabia is illustrated. Annex 4A presents separate figures for female- and male-forecasted NCD burdens; annex 4B presents supplementary details for intervention assumptions.

METHODS

This chapter forecasts several scenarios that assume changes to the prevalence of overweight/obesity, insufficient fruit and vegetable intake, and insufficient physical activity. These estimates are applied to the health and demographic situation in Saudi Arabia; several scenarios—of life expectancy, DALYs, deaths averted, and healthy life expectancy (HALE) that arise from changes in NCD burdens—are forecast. HALE is defined as the average years of life that a person can expect to live in “full health” (WHO 2020).

This chapter quantifies, from 2020 to 2050, disability and life years lost due to overweight- and obesity-related NCDs in Saudi Arabia. NCDs cause not only premature death (years of life lost, or YLLs) but also disability (years of life disabled, or YLDs). When summed, these two measures form the DALY value. 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, in subpar health due to disease. DALYs are often used as a basis for health policy making as well as for setting intervention priorities. The DALY calculation appears as follows:

DALY = YLL + YLD (4.1)

Minimizing premature death and disability is the equivalent of maximizing healthy life years. HALE represents a more intuitive way to think about reductions to disability and premature mortality. These reductions can be interpreted as a gain in healthy years lived, or a gain in HALE. This summary measure is adjusted for years that are lived with disease and injury:

HALE = ex0 –YLD (4.2)

where ex0 equals life expectancy at birth.

First, the baseline (2020) NCD burden estimates for males and females in Saudi Arabia were retrieved. The data source for these baseline estimates of the DALY burden for specific NCDs was the Global Burden of Disease (GBD) database (IHME 2018b). Next, a baseline scenario was assumed in which the DALY burden remains unchanged from 2020 to 2050—save for the fact that the Saudi population distribution shifts to older ages. The population size and age structure values for 2020, 2030, 2040, and 2050 were based on United Nations (UN) population estimates for Saudi Arabia (UN DESA 2019b). This population projection, combined with the 2017 GBD database, allowed forecasting to 2050 the DALY burden by NCD, sex, and age group. Table 4.1 shows the total DALYs for each of the key health conditions.

Demographic life tables were used to calculate baseline (2020) life expectancy, healthy life expectancy, and deaths averted. A life table is a tool used by demographers to quantify mortality and life expectancy at various ages.