===== Socio-demographic Index (SDI) =====

The **Socio-demographic Index (SDI)** is a composite metric developed by the **Global Burden of Disease (GBD) Study** to quantify a region or country's **level of socio-demographic development**.

==== Components ====
SDI is calculated as the geometric mean of three indicators:
  * **Income per capita** (lag-distributed)
  * **Average educational attainment** (years of schooling among individuals aged 15+)
  * **Total fertility rate** (TFR) among women under age 25

==== Scale and Interpretation ====
  * Ranges from **0 (lowest development)** to **1 (highest development)**
  * Enables categorization of countries/regions into:
    * **High SDI**
    * **High–middle SDI**
    * **Middle SDI**
    * **Low–middle SDI**
    * **Low SDI**

==== Purpose ====
  * To analyze how disease burden varies by socio-demographic status
  * To provide a **contextual framework** for interpreting health outcomes and risk factor exposure
  * To support **comparative modeling** across countries with different development levels

==== Applications ====
  * Used extensively in **GBD estimates** of:
    * Mortality
    * Disability-Adjusted Life Years (DALYs)
    * Risk factor attribution
  * Facilitates **longitudinal and cross-country comparisons**
  * Supports **projections** of future health burden

==== Example ====
  * Regions with **low SDI** often have a higher burden of infectious diseases and maternal mortality.
  * Regions with **high SDI** have a higher burden of non-communicable diseases (e.g., stroke, ICH), often with different risk factor profiles (e.g., aging, lifestyle, pollution).

==== Related Entries ====
  * [[Global burden modeling]]
  * [[SDI Region]]
  * [[Disability-Adjusted Life Year (DALY)]]
  * [[Intracerebral hemorrhage epidemiology]]