The NHS is performing so well that it does not need to undergo the radical transformation planned by the coalition, according to a new study published by the British Medical Journal.

While the health service in England has some weaknesses, it should be left to continue making improvements that began when Labour was in power, and not face another massive upheaval, an analysis by health researchers led by Professor David Ingleby of Utrecht University in the Netherlands concluded.

Their findings "do not support complacency about the current performance of the health system in the UK", the authors stress. "They do, however, cast serious doubt on any claim that there is widespread popular support for radical reform.

"Improvements are needed, but continuation and expansion of the measures already set in motion – more of the same – seems to be a better formula than totally rebuilding a system that, by international standards, already works remarkably well."

The researchers based their findings on two recent Commonwealth Fund reports comparing the NHS's performance across the UK, and patients' perceptions of it, with that of the health systems of 13 other countries.

"The main messages are that the NHS outperforms other high income countries on many measures, despite spending less than most of them; it enjoys the highest levels of public confidence and satisfaction of all the countries studied; [and] the effects of increased investment and policy improvements over the past decade are clearly visible," said Ingleby.

But while healthcare is more accessible, better organised, safer and more patient-centred in the NHS than elsewhere, ongoing concern about some of the clinical outcomes it achieves in patients is a worry, they say. "Three measures warrant particular concern: deaths amenable to healthcare; survival rates for breast cancer; and survival after acute myocardial infarction," they add.

The Department of Health said the NHS could not be allowed to stand still. "This analysis highlights concerns around clinical outcomes, and the fact the current system has to improve. Separately, another report from Age UK and the National Osteoporosis Society today said our reforms could improve patient care," said a spokesman.

"The independent NHS Future Forum confirmed that every health system in the developed world faces the same challenges, but that they won't be met by the NHS doing more of the same. That is why our plans will hand power to GPs, put patients at the heart of the NHS, and reduce needless bureaucracy."