Researchers reviewed all available data on the use of incentives to reward primary care clinicians who improve the quality of their services.
They concluded that policymakers need to proceed with caution before setting up incentive schemes and think carefully about the way they are designed.
The team, led by Professor Anthony Scott and Dr Peter Sivey from the University of Melbourne, said unintended consequences were a particular problem with such schemes.
There was a possibility, they said, that incentives may not produce any effect, could have negative outcomes or that efforts could be redirected away from non-incentivised work.
The researchers said that, despite the popularity of these schemes, they could only find seven appropriate studies examining how schemes worked in practice.
Dr Sivey said that poor design led to substantial risk of bias in most of the studies assessed. 'In particular, none of the studies addressed the ability of primary care physicians to opt into or out of the incentive scheme or health plan,' he said.
The seven studies looked at interventions covering a variety of health-related issues.
These included asthma, diabetes, smoking cessation, childhood immunisation and cervical, mammography and chlamydia screening.
Dr Sivey said: 'There is little rigorous evidence about whether financial incentives do improve the quality of primary healthcare, or of whether such an approach is cost-effective relative to other ways of improving the quality of care.'
He said it was 'important' that data began to be collected to assess 'this critical issue'.
'There are ways of conducting high-quality research that could find solid answers,' he said.
A Department of Health spokeswoman said financial incentives have been shown to improve performance.
'QOF has succeeded in making quality improvements a core part of general practice,' she said. 'It has also helped to make real progress in addressing health inequalities.
She added: 'QOF is just one part of an overall framework for improving quality informed by professional standards. It is continuously reviewed and updated to reflect current performance and up to date evidence of best practice.'
