Forget money or compassion. Even death is not distributed equally around the world.
In high-income countries, people typically die in old age of chronic diseases such as cancer or cardiovascular problems.
While in low-income countries, death comes primarily from infectious and perinatal diseases and strikes at a young age, research shows.
Despite massive international efforts to improve global health, a new analysis of nearly four million scientific articles finds that research is disproportionately focused on diseases that primarily afflict wealthy countries.
Correspondingly, less research attention is given to diseases of the developing world, increasing global health disparities.
"Our study demonstrates that health research follows the market but likely not just because of the market," said lead author James Evans, an associate professor of sociology at University of Chicago.
"Countries want to fund research that burdens their populations. Where this leads to inequality in health knowledge is that the disease burden of rich and poor countries are different, and that rich countries obviously produce much, much more research," Evans explained.
To conduct this research, Evans and co-authors Jae-Mahn Shim of University of Seoul and John P.A. Ioannidis of Stanford University drew upon data from the World Health Organisation (WHO) and MEDLINE, the National Library of Medicine's database of biomedical journal articles.
The researchers measured the global disease burden - the number of healthy life years lost to disease or disability - of 111 medical conditions.
Though they expected to find at least a weak influence of disease burden on research, their analysis found no relationship between the two factors.
For comparison, the researchers calculated the global "market" for treatment of each disease by multiplying the local disease burden for each country by the wealth of that country.
Unlike disease burden alone, the global market for treatment showed a strong relationship with research, said the study published in the journal PLoS ONE.
"For every $10 billion in wealth lost to a disease, the number of research articles on that condition rose by three to five percent," Evans added.
The researchers said the world's poor are in "double jeopardy" - experiencing the highest health burden from diseases that are studied the least.
Greater investment should be made to boost scientific research within poorer countries, they suggested.
