Historians will not be kind in their assessment of the coalition government's record on NHS reform, according to the King's Fund.
The health thinktank said that this had been a Parliament of two halves for the NHS.
The organisation argued that the first half was "dominated" by debate on the Health and Social Care Bill, which was designed to devolve decision-making to GPs.
The second half was taken up with "limiting the damage" caused by the Bill.
"An unnamed senior government source has recently acknowledged that the decision to promote the Bill was 'a huge strategic error' and, as we show, its effects were both damaging and distracting," the report said.
The King's Fund, which looked at six major themes of the coalition government's reform programme, concluded that the changes had resulted in greater marketisation of the NHS.
But the thinktank stressed that claims of mass privatisation are exaggerated.
In addition, the organisation argued that new systems of governance and accountability resulting from the reforms are "complex and confusing" and absence of system leadership is "increasingly problematic" when the NHS needs to undertake major service changes.
The King's Fund called on the next government to continue the "emphasis on patient safety" and quality of care, but with less emphasis on regulation and more on supporting NHS leaders and staff to improve care.
A spokesman for Health Secretary Jeremy Hunt said: "We welcome the King's Fund's recognition that the government's focus on patient safety and integrated care is right for the NHS's future.
"This independent assessment also puts paid to Ed Miliband's myth that the reforms were about privatisation, and highlights why both the public and the health sector should be wary of Labour's plans for upheaval and reorganisation."
Andy Burnham MP, the Shadow Health Secretary, said: "Labour warned David Cameron that his reorganisation would damage the NHS and we now have independent authoritative evidence that that is what has happened.
"People will remember patients, nurses, doctors and midwives lining up in their thousands and pleading with the government to call it off. But they ploughed on and plunged the NHS into the chaos we see today.
"The vast majority of NHS staff now say that Cameron's reorganisation has harmed patient care.
"The sad truth is that by turning the NHS upside down and causing a crisis in A&E, Cameron has made care problems more likely, not less."