Rethinking health systems in the context of urbanisation: challenges from four rapidly urbanising low-income and middle-income countries.

The world is now predominantly urban; rapid and uncontrolled urbanisation continues across low-income and middle-income countries (LMICs). Health systems are struggling to respond to the challenges that urbanisation brings. While better-off urbanites can reap the benefits from the 'urban advantage', the poorest, particularly slum dwellers and the homeless, frequently experience worse health outcomes than their rural counterparts.