But although the plans are 'far from perfect', they represent the only chance the NHS has to improve health and care services in the face of an 'unpredecented slowdown in funding', according to a King's Fund report.
Controversial STPs are being drawn up to reshape health and social care in 44 'footprint' areas across England by NHS commissioners, providers and local authorities. Plans released early for some areas - in some cases by disgruntled local authorities - have spelled out plans to cut NHS costs by shifting work to primary care or cutting services and have been labelled 'undeliverable' by some local GPs.
GPs and health campaigners have long complained about the plans being drawn up in secrecy, and one former senior NHS official recently warned that the 'shameful' rapid pace at which they were being rolled out risked 'financial meltdown' for parts of the health service.
The King's Fund report today, Sustainability and transformation plans in the NHS, echoes many of these warnings, saying that the development of STPs has been 'beset by problems'.
Local government involvement in the plans - which was meant to play a crucial role in using them to create a more integrated health and social care landscape - has been patchy, the report found.
There has been too little time to involve clinicians and frontline staff, and patients have been 'largely absent from the process, it warns.
Officials leading the development of STPs are 'struggling with a confused process', with changing or unclear deadlines and guidance from national NHS organisations.
But despite the concerns, the King's Fund report warns that making STPs work is the only option for the NHS in the foreseeable future.
NHS under pressure
The think tank's chief executive Chris Ham said: ‘The introduction of STPs has been beset by problems and has been frustrating for many of those involved, but it is vital that we stick with them.
‘For all the difficulties over the last few months, their focus on organisations in each area working together is the right approach for improving care and meeting the needs of an ageing population. It is also clear that our health and care system is under unprecedented pressure, and if STPs do not work then there is no plan B.
‘The progress made so far has only happened because of the hard work of local leaders who have been prepared to work around the difficulties. It is vital that NHS national bodies learn the lessons so far, so that we can see STPs fulfil their potential.’
The report says the STPs are a 'complex workaround' that can help the NHS integrate services despite the emphasis on competition created by former health secretary Andrew Lansley's Health and Social Care Act 2012 reforms.
It calls for improvements in the consultation and involvement of local clinicians and patients in the plans, for clearer national guidance and better arrangements to help local health and social care commissioners and providers work together on shaping the plans.
Plans drawn up at speed under the STP process must be 'stress-tested' to check that financial assumptions and ways of working they specify are workable, the report warns.
'If this can be done, collective action through STPs offers an important opportunity for improving health and care services in England,' the King's Fund report says.
'There have been significant issues with the STP process so far. But place-based working is by far a preferable alternative to the "fortress mentality" whereby NHS organisations act to secure their own future regardless of the impact on others.'