The NHS has been declared the best healthcare system by an international panel of experts who rated its care superior to countries which spend far more on health.

The same study also castigated healthcare provision in the US as the worst of the 11 countries it looked at. Despite putting the most money into health, America denies care to many patients in need because they do not have health insurance and is also the poorest at saving the lives of people who fall ill, it found.

The report has been produced by the Commonwealth Fund, a Washington-based foundation which is respected around the world for its analysis of the performance of different countries' health systems. It examined an array of evidence about performance in 11 countries, including detailed data from patients, doctors and the World Health Organisation.

"The United Kingdom ranks first overall, scoring highest on quality, access and efficiency," the fund's researchers conclude in their 30-page report. Their findings amount to a huge endorsement of the health service, especially as it spends the second-lowest amount on healthcare among the 11 – just £2,008 per head, less than half the £5,017 in the US. Only New Zealand, with £1,876, spent less.

In the Commonwealth Fund study the UK came first out of the 11 countries in eight of the 11 measures of care the authors looked at. It got top place on measures including providing effective care, safe care, co-ordinated care and patient-centred care. The fund also rated the NHS as the best for giving access to care and for efficient use of resources.

The only serious black mark against the NHS was its poor record on keeping people alive. On a composite "healthy lives" score, which includes deaths among infants and patients who would have survived had they received timely and effective healthcare, the UK came 10th. The authors say that the healthcare system cannot be solely blamed for this issue, which is strongly influenced by social and economic factors. Although the NHS came third overall for the timeliness of care, its "short waiting times" were praised. "There is a frequent misperception that trade-offs between universal coverage and timely access to specialised services are inevitable. However, the Netherlands, UK and Germany provide universal coverage with low out-of-pocket costs while maintaining quick access to speciality services,", the report added.

The NHS also outperforms the other countries – which include France, Germany and Canada – in managing the care of people who are chronically ill, the report said.

Dr Mark Porter, leader of the doctors' union, the British Medical Association, said the fund's findings were "clear evidence that our much-maligned NHS is one of the top-performing healthcare systems in the world."

However, he warned that the service's achievements were now at risk. "We should not be complacent as we are facing pressures that are threatening the high-quality care that the Commonwealth Fund has rightly praised. A combination of rising patient demand, staff shortages and falling funding is undermining the very foundations of the NHS, as is the constant short-term interference from politicians of all colours."

Dr Peter Carter, chief executive of the Royal College of Nursing, said: "I'm absolutely thrilled to see this because it reinforces that this is a very good NHS, despite the fact that it has such a low level of funding relative to other countries."

The health secretary, Jeremy Hunt, who has been criticised by some senior doctors for painting an unfairly negative picture of NHS staff and the quality of care provided, welcomed the report. "NHS staff work incredibly hard to care for patients and these encouraging results pay testament to that," he said.

• This article was amended on 23 June 2014 to clarify the data sets that the survey used.