Singapore began the process of "restructuring" hospitals in the 1980s.
Under restructuring, a public hospital is granted autonomy in its operations, though major issues or changes would require government approval.
This came after a successful pilot in 1984 during which National University Hospital (NUH) was run as a corporatised institution.
Singapore General Hospital (SGH) was the first to be restructured, in April 1989. This was followed by the then Kandang Kerbau Hospital - now known as KK Women's and Children's Hospital - and Tan Tock Seng Hospital.
NUH and the now-defunct Toa Payoh Hospital were also restructured. Alexandra Hospital remained a government-run facility.
The restructured hospitals were free to develop their own identity and make service improvements to draw patients.
But this competition led to some issues such as higher salaries.
2000: TWO NETWORKS
In 2000, the government reorganised the public health sector into two networks, National Healthcare Group (NHG) and Singapore Health Services (SingHealth).
It also announced that Alexandra Hospital, Woodbridge Hospital - known as the Institute of Mental Health today - and polyclinics would be restructured by April 2001.
These institutions were then integrated into the two networks.
Each network had a variety of services, from acute to primary care.
There were two objectives for the change, according to the Government. One was to facilitate referrals between the different institutions and coordinate care for patients.
The other was to spur competition between the two groups to provide better care at a lower cost.
This system, however, mostly involved public health facilities and did not rope in the private sector.
LATE 2000s: SIX SYSTEMS
The move towards six regional health systems, each anchored by a general hospital, took place from 2007 to 2009.
Four regional groups were formed, centred on SGH, NUH, Tan Tock Seng Hospital and Changi General Hospital.
This was expanded to six when Khoo Teck Puat and Ng Teng Fong hospitals opened.
For the Eastern Health Alliance (EHA), which oversaw Changi General Hospital, there was a two-step process.
In 2009, the Changi General Hospital Board, a subsidiary under SingHealth, was established.
This was followed by the formal incorporation of the EHA in early 2011.
The regional groups worked with private and charity-run health providers.
For instance, EHA partnered St Andrew's Community Hospital, which is run by a voluntary welfare organisation.
However, services were uneven across the groups. For instance, only two had polyclinics under their management.
2017: THREE CLUSTERS
The latest reorganisation, announced last Wednesday, will see the six regional groups streamlined into three integrated clusters by early next year.
SingHealth will merge with the EHA, and NHG will join forces with Alexandra Health System, while National University Health System will be paired with Jurong Health Services.
Each cluster will offer a full range of services, including polyclinics and community hospitals.