The pressure is on. As we approach the Þrst anniversary of primary care trusts holding 75% of the English NHS budget, their operation, success and existence will be scrutinised. They have the power, resources and opportunity to transform local health and social services - but will they be allowed the time to show their worth?

Less than three years ago, PCTs became England's lead health organisations. In this time, these nascent bodies have grappled with the huge work load associated with organisational change, while maintaining and striving to improve services. They have achieved much in a short time.

Now it is time to take stock and see how PCTs measure up against their objectives. The advantages of one organisation taking an overview of the continuum of prevention, diagnosis, treatment and care are enormous. But juggling so many balls can mean that relatively simple tasks take precedence over the trickier challenges.

Of their three core roles - to improve the health of their local population and reduce health inequalities; to manage and develop primary and community health services; to commission hospital and specialist services - it is the latter that continues to dominate the agenda.

It is easier, and by some measures more cost-effective, to purchase hip operations at the same hospital that hip operations have always been purchased at than to prevent the need for hip operations in the Þrst place. The transition from a medical model (that treats a disease) to a holistic one (that supports a person) is not easy. But the status quo is not an option.

The latest health survey for England shows that despite more spending on the NHS, we are getting sicker. Between 1993 and 2002, the prevalence of long-standing illness increased from 40% to 44% for men and from 40% to 46% for women. Almost one in Þve of us has at least one life-limiting illness such as chronic obstructive pulmonary disease, diabetes or arthritis.

People living with chronic conditions, especially the elderly and frail, need to receive care and support close to home. Many PCTs are already using different approaches to managing patients by developing services in community settings. This not only improves the patients' quality of life, but can help reduce demand for hospital services.

PCTs are increasing patients' choice of treatment by offering negotiated packages with healthcare advisers, nurses or GPs. Some organisations are already engaging with local clinicians and alternative providers to develop solutions to long-standing problems.

However, as the Wanless report stressed, the core impact on health outcomes is "not the way in which the service responds over the next 20 years, but the way in which the public and patients do".

The forthcoming review "securing good health for the whole population", also led by Derek Wanless, will give new impetus to prevention and the wider determinants of health. One of the questions it will seek to answer is whether PCTs have the capacity to deliver on preventive measures and public health. Indications are that public health is languishing at the bottom of PCT priorities. This has to change.

Some might argue that the political imperatives of cutting waiting times interfere with PCT development in other areas. Patients might argue that the NHS must Þnd a way of doing both. PCTs surely have a responsibility to patients.

Increasingly, as waiting times improve, local targets and priority setting will become the norm. On the other hand, half a century of centralisation has made NHS organisations risk failure. Too many PCTs still wait for permission or instructions from the centre before taking the risks the NHS needs.

All in all, PCTs are doing a great job. They are travelling in the right direction and know they must keep up the momentum. They now need a period of stability to fulÞl their potential: to learn from each other, to invest time and resources in long-term strategies and to make brave decisions that beneÞt the health of the people they serve.

· Margaret Mythen is chief executive of the New Health Network

For more on the New Health Network: www.newhealthnetwork.co.uk