The demand for healthcare is rising faster than the supply of doctors. The problem is most acute in the developing world, though rich countries are not immune. It does not help that healthcare is notoriously inefficient. Whereas America's overall labour productivity has increased by 1.8% annually for the past two decades, the figure for healthcare has declined by 0.6% each year, according to Robert Kocher of the Brookings Institution and Nikhil Sahni, until recently of Harvard University. But it is in poor countries that interest in alternative ways of training doctors and in alternatives to doctors themselves has produced the most innovation.