YLD

YLD, or Years Lived with Disability, is a health metric used to quantify the burden associated with non-fatal outcomes. It measures the years lived in less-than-perfect health due to disease or injury. In the Global Burden of Disease framework, YLD is one component of disability-adjusted life years (DALYs), the other component being Years of Life Lost (YLL). YLDs allow comparisons of non-fatal health loss across diseases, populations, and over time.

Calculation methods include prevalence-based and incidence-based approaches. In the prevalence-based form, YLD equals the number of people living with a condition multiplied by a disability weight that reflects the severity of the health loss on a 0 (perfect health) to 1 (death) scale. In incidence-based approaches, new cases are multiplied by the duration of the condition and the disability weight. Disability weights are derived from surveys and expert judgment and reflect perceived severity, and they can vary by condition and context.

YLDs are aggregated to estimate total non-fatal burden and are used to prioritize health interventions, monitor changes in health, and allocate resources. Limitations include reliance on subjective weights, data quality issues, and potential cultural bias; some health states may be difficult to capture with a single weight, and gaps in data can affect estimates.