GPs excluded almost 6 per cent of eligible patients from their quality and outcomes framework last year claiming their cases did not suit the bonus scheme indicators.
The figures came as new research from the Centre for Health Economics found substantial evidence of GPs 'gaming' their exemptions in order to only include those patients whose outcomes or treatments would gain them maximum scores in the framework.
Figures published by the Information Centre for health and social care this week show that just under 6 million patients were excluded from the framework in 2006-07, an increase of 5 per cent since 2005-06. The highest exemptions were for indicators related to outcomes - such as improved health measures - while the lowest were for processes, such as prescribing the recommended medication.
It noted the number of exemptions could 'influence the level of financial reward to [GP] practices', but it did not comment further.
However, new research by York University's Centre for Health Economics, Doctor behaviour under a pay performance contract, found GP practices which did not score well in 2004-05 reported much higher levels of exemptions in 2005-06.
The researchers estimated 11 per cent of those exemptions were inappropriate and concluded that the framework 'provides perverse incentives for gaming of exceptions'.
The biggest increase in exclusions was among mental health patients.
NHS Alliance chair Dr Michael Dixon told HSJ: 'Although some GPs will be cheating the exemptions, most will be bona fide.'
He said a problem with measuring mental health indicators was that these required an in-depth interview with the patient which was often not appropriate for distressed people.
Health minister Ben Bradshaw said: 'There are already many safeguards in place to prevent misuse of exception reporting.'
The framework was under constant review, he added.