An Extraordinary Collaborative Effort: Disability Adjusted Life Years (DALYs) for 306 Countries

Last fortnight’s blog post featured a synopsis of the mighty Global Burden of Disease Study on life years lost across different countries and across the world over time due to different diseases. A subsequent paper has recently been published in the Lancet that uses a standardised framework and method to estimate summary measures of health loss expressed as DALYs and Health Life Expectancy.[1] Health loss was estimated for 306 diseases/conditions across 188 countries at regular intervals between 1990 and 2013. Headline messages from this 46 page study are as follows:

  1. Worldwide life expectancy rose by 6.2 years (from 65 to 71 years) over the 23 years of the study.
  2. Age-standardised DALYs fell by a mighty 27%.
  3. Indicators (total DALYs and age-specific DALYs) improved dramatically for communicable diseases; and for maternal, neonatal and nutritional diseases.
  4. Age-adjusted DALYs have also declined for non-communicable disease – a surprise?
  5. Some communicable diseases (notably leishmaniasis and dengue) bucked the trend for communicable diseases as a whole and registered a recent increase in DALYs. The CLAHRC WM Director questions the finding regarding leishmaniasis – he suspects that visceral leishmaniasis, at least, is declining.
  6. The greatest causes of DALYs were ischaemic heart disease, pneumonia, stroke, spinal pain, and road injuries. The CLAHRC WM Director suspects that mental illness is underestimated in this study?
  7. Leading causes of DALYs are highly variable across countries.
  8. Progress has been most rapid in the latter part of the survey period thanks to major reductions in HIV/AIDS and malaria, along with maternal, neonatal and nutritional disorders.
  9. DALY rates for neoplasms and cardiovascular disease are minimally related to socio-economic status except that risk for cardiovascular disease drops at the very highest economic level.

The health of the world’s population really has improved and to quite a dramatic degree. This has happened even in countries that have not prospered economically. The GBD study is a remarkable achievement, up there with the human genome project. It shows that science is a massive public good, and is a stark vindication of Enlightenment values and investment in research.

— Richard Lilford, CLAHRC WM Director

Reference:

  1. GBD 2013 DALYs and HALE Collaborators. Global, regional, and national disability-adjusted life years (DALYs) for 306 diseases and injuries and health life expectancy (HALE) for 188 countries, 1990–2013: quantifying the epidemiological transition. Lancet. 2015; 386: 2287-323.
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