Researchers compared the performance of practices since the QOF was introduced in 2004, in terms of points scored and achievement rates.

They found that practices with fewer than 3,000 patients had greater variation in performance than larger practices.

Such practices made up 45.1% of the bottom 5% of practices, but also accounted for 46.7% of the top 5%.

The study’s authors believe that small practices are losing out because achievements over the maximum threshold are not rewarded.

Writing in the British Journal of General Practice, they said: ‘The payment system does not adequately recognise the achievements of high-performing practices, many of which are small.’

Dr Peter Swinyard, national chairman of the Family Doctor Association, would not be in favour of a move to 100% thresholds, despite the possible benefits for small practices.

‘100% is a silly threshold for anything,’ he said. ‘There are always some people you can’t get hold of.’ Dr Swinyard believes that increasing thresholds could demotivate GPs.

‘I actually think it doesn’t stimulate people to try harder, they’re more likely to give up’. He added: ‘It would increase people trying to game the system and exception report people they shouldn’t.

‘I don’t think it would improve the quality of care for patients.’