The Global Burden of Diseases, Injuries and Risk Factors Study 2015 (GBD)¹ brings together the most recent epidemiological data according to year, age and sex from 195 countries and territories. The Institute for Health Metrics and Evaluation (IHME) collates data on global mortality, years lived with disability, disability-adjusted life-years and risk factors, with a view to evaluating major public health initiatives such as the Millennium Development Goals (MDGs) and the newly launched 17 Sustainable Development Goals (SDGs).

The GBD illustrates the most pressing challenges and commendable achievements of collective efforts to improve human health and wellbeing. Although globally life expectancy has increased since 1980, conflict and interpersonal violence has resulted in levelling off or reduction in some countries, with male life expectancy in Syria decreasing by 11·3 years between 2005 and 2015. The combination of socioeconomic development and an ageing population is contributing to decrease in some indices, such as childhood undernutrition, but increases in others, such as low physical activity and high body-mass index. 

The essential purpose of the GBD is to record all that is known about descriptive epidemiology to produce reliable measures of global health and useful analysis of these measures. Each report produces an update on worldwide disease burden so as to advance the methods used to produce robust measurements and comparisons. Publication of the GBD in an academic journal emphasises the scientific basis for the information that is subject to peer review and public scrutiny. The GBD is thus an objective instrument of quantifiable progress in global health. At a national level, the GBD estimates support countries by enabling them to measure successes, identify important gaps, make comparisons with other countries and set new priorities. These estimates are an important tool for policy makers, non-governmental organisations, practitioners and other stakeholders. China, Mexico and the UK included the first subnational level analyses in GBD 2013, with GBD 2015 expanding these analyses to also include several other countries such as Brazil, South Africa, Japan and India.

At a global level, the GBD functions as an accountability tool. The socio-demographic index (SDI) is a new technological development of GDB 2015. This indicator is derived from measures of educational attainment, fertility rate and per capita income, and is critical to measuring the impact of public health interventions by separating secular trends that are driven by socioeconomic development from overall progress. GBD 2015 produced a health-related index of sustainable development (SDG) for each country and examined its relationship with the SDI, finding that some countries, including several in western Europe and Latin America, had SDG indices that were higher than expected on the basis of SDI alone, whereas others, such as the US and India, performed poorer than expected. These findings indicate that progress in health can be achieved even where general economic development is less than expected.

The next challenge is to move beyond assessing individual health-related SDGs to investigating the links between different goals. Factors such as education, access to clean water and sanitation, gender equality, political stability, justice and strong civil institutions all have a profound impact on health. What is now important but less clear is how to analyse and measure these relationships. 

Reference

1. Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980–2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet 2016; 388:1459-1544