Sociodemographic index (SDI)
A number that identifies where countries or other geographical areas sit on the spectrum of development. Expressed on a scale of 0 to 1, SDI combines rankings of (1) the incomes per capita (how much money people earn on average), (2) average educational attainment (how many people have completed high school or university), and (3) fertility rates (how many women give birth) of all areas in the GBD study. Health outcomes are closely tied to this measure. See GBD Socio-Demographic Income regions.
Stroke
A stroke occurs when the blood supply to part of the brain is suddenly interrupted or when a blood vessel in the brain bursts, spilling blood into the spaces surrounding brain cells. Brain cells die when they no longer receive oxygen and nutrients from the blood or there is sudden bleeding into or around the brain.
