Patients will not benefit from the new NHS pay system until staff working patterns also start to change, say the King's Fund.
A new report says that national implementation of the new pay and career development structure for care staff, Agenda for Change, has exceeded all cost estimates.
Transferring staff to the new pay system became an end in itself for NHS managers, says the report, rather than a way to achieve long-term benefit for patients.
It warns that the new NHS pay system needs to be properly embedded for staff and patients to reap the benefits.
King's Fund Chief Executive Niall Dickson said: "Agenda for Change was intended to modernise more than a million NHS jobs and improve patient care.
"However, this limited but important study shows that as yet there are few signs it has delivered increased productivity or transformed practice and there is evidence that many staff are far from satisfied by the process."
The King's Fund report suggests that a national audit of the cost and impact of Agenda for Change should take place.