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What’s the difference between an ACS and an ACO?

What’s the difference between an ACS and an ACO?
By Carolyn Wickware Reporter
10 August 2017



This week NHS England published the first contract for ‘accountable care organisations’ (ACOs), an integrated care system with full responsibility for all health and care services in the area.

The contract defines an ACO and its responsibilities, and in doing so differentiates it from an accountable care system (ACSs) and a sustainability and transformation partnership (STPs), which had previously been a difficult task.

The Next Steps of the Five Year Forward View document described the progression of an integrated care system as an STP becomes an ACS, which then becomes an ACO but did little in the way of defining the systems.

So what does the new contract reveal?

An ACS: ‘laying the foundation’

In June, NHS England announced eight advanced STPs, which would become the first ACSs in England.

The new contract describes an ACS as an area ‘in which commissioners and providers, in partnership with local authorities, take explicit collective responsibility for resources and population health’.

It adds: ‘In return, they will gain greater freedom and control over the operation of their local health system and how funding is deployed.’

The document says that NHS England expects to add to the list of ACSs as more STPs develop and move to more advance stages, ‘laying the foundation’ for greater integration of health and social care across the country.

An ACO: ‘lengthy and complex’

According to the document ACSs and ACOs have the same objectives of integrating care and having a single approach to using resources but they are different in that ACOs are contractually integrated.

Commissioners within an ACO hold a contract with a single organisation for the majority of health and care services, which the document describes as ‘lengthy and complex’.

An ACO model supposedly simplifies governance and decision making by bringing together funding streams and allowing one provider organisation to decide how to allocate resources and design care for its local population.

As a result, ACOs are reliant on a ‘strong underlying approach to care design, engagement and collaboration’.

The document says: ‘For these reasons, most parts of the country are looking to become ACSs before they consider whether to introduce ACOs for some or all of their local population.’

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