The 40 national GP commissioning pilots, which go live this week, will come under close scrutiny to assess their impact.

The evaluation over two-and-a-half years aims to identify the strengths and limitations of the different commissioning models.

It will also compare their performance with total purchasing projects and health authority commissioning.

Birmingham University's health services management centre will carry out the study.

It will look at the groups' functions and the extent to which they involve stakeholders, such as nurses, community health councils and social services. It will also consider the groups' costs and impact.

The pilots, planned to run for two years, will be part of the process of forming primary care groups in April 1999.

The study's findings will play a key role in informing the Department of Health and the NHS as implementation of the white paper gathers pace.

As well as the overall study of the 40 pilot sites, the research team will develop six of the sites as detailed case studies.

The director of the health economics faculty at HSMC, James Raftery, said: 'This will definitely be a research project which remains highly relevant throughout its duration.

'We will work closely with the DoH and with colleagues in the sites to make sure that our findings make their way quickly into the wider development of policy.'