GPs may be getting benefiting financially as patients suffer poorer standards of service, according to a study reported on the British Medical Journal website bmj.com.
The report says that this may reflect the lack of further incentives after attainment of upper payment thresholds, a phenomenon known as the "ceiling effect".
And it suggests that if patients are to benefit, either the thresholds for GPs may need to be removed or targets made more challenging.
Researchers based at the Universities of Birmingham and Manchester focused on the care of patients with diabetes, which has improved over the last decade. But they say that this improvement does not appear to have been a direct result of the Quality and Outcomes Framework (QOF).
And they say that as it stands, the QOF may even lead to reduced levels of care for some patients.
The framework was introduced in 2004 to boost standards of primary care by linking financial incentives to performance indicators for all GPs in the UK.