Britain has narrowly edged out Australia's healthcare system to take the coveted top spot in a global study which ranked the quality of healthcare systems based on 72 indicators.

The study, conducted by US think tank The Commonwealth Fund, compared the healthcare systems of 11 high-income countries to measure performance in five key domains: care process, access, administrative efficiency, equity and health care outcomes.

But experts warn a self-congratulatory pat on the back risks overlooking the reality faced by some of Australia's most vulnerable patients.

"All self-congratulations and praise should be tempered by the realisation that Australia ranks very poorly on equity," Dr Lesley Russell from the University of Sydney's Menzies Centre for Health Policy says.