One in seven emerging clinical commissioning groups could be asked to reform because they are too small, HSJ research suggests.

Analysis of information from all primary care trusts, collected over the past two months, has identified 331 CCGs across England. The number has shrunk since March, when a similar exercise estimated there were 380 groups.

HSJ understands a population of around 50,000 is likely to be seen as the minimum for CCGs. The Department of Health has not ruled out allowing smaller groups but 47 CCGs are made up of GP practices with fewer than 50,000 patients; some have as few as 5,000.

Draft guidance issued last week on the authorisation of CCGs said they would have to demonstrate competence including “proper constitutional and governance arrangements” and “the capacity to deliver all their duties and responsibilities” (see below).

CCGs will be allocated running cost budgets based on the number of patients they cover, prompting fears that those with small populations may struggle.

Primary Care Trust Network director David Stout said the smallest groups would be “hard pressed to prove they are viable”.

He said it would be harder for smaller CCGs “to demonstrate the capability and experience to do the job within a maximum running cost”.

“You have to have whole series of things in place,” he said. “You could come up with ways of sharing functions but at some point you say ‘why not just merge?’”

The average population of a CCG is now 158,000 – 18 per cent higher than the 133,500 in March – and there are now 24.3 practices per CCG compared with 19.8 in the spring.

NHS East of England director of commissioning development Paul Zollinger-Read said the increase in CCG size had been expected and growth from a small base had allowed clinicians to take “ownership” of groups. He said that even a CCG covering a population of 50,000 would be “incredibly challenging”, while CCGs made up of a single practice were “unlikely” to be sustainable.

However, the Red House CCG, a single practice in Hertfordshire, plans to remain independent. Practice manager Kenneth Spooner said it was “moving ahead on the basis that we are viable”.

“If it is financially viable and doable then we will keep going on our own,” he added. “Nothing is insurmountable until we are told we’ve got to merge.”

Simon Hambling, chair of Cambridgeshire’s GP senate, said the county was likely to end up with a single CCG, where it had previously had six.

He said: “They moved the goalposts quite significantly for us. There’s been some wasted time, a dashing of some people’s expectations. People thought there would be a lot more freedom to operate which is just not going to be the case.”