How PSI Measures Its Health Impact

PSI estimates its health impact using the disability-adjusted life year (DALY), a metric developed by the World Bank and the World Health Organization to determine disease burden. One DALY equals one year of healthy life lost due to illness or death. PSI adds one year of healthy life with every DALY averted.

To calculate DALYs averted, PSI has developed “DALY models” that incorporate a wide range of factors, from country-specific disease prevalence to information on the effectiveness of health products at preventing or treating disease. Disease prevalence changes from year to year, so PSI updates its models annually to take into account the latest on the global burden of disease as well as the latest research data on the efficacy of interventions. These updates enable PSI to continually report more accurate health impact estimates. More importantly, they help PSI to refine its strategy, ensuring that programs are targeted, economical and effective.