The Government has decided to phase out a funding arrangement called the Minimum Practice Income Guarantee (MPIG) over a seven-year period, beginning in April - a move that doctors' leaders have warned could force around 100 GP practices to close.
MPIG means many smaller GP practices are guaranteed a minimum level of funding that is not dependent on the number of patients on their practice list.
NHS England has published an anonymised list of 98 'outlier' practices that could lose more than £3 per patient per year.
Some practices on the list will lose more than £100 per patient per year while others stand to lose around £20 or £30 per patient.
A GP who has taken all of his patients out of an information sharing scheme justified his decision "because none of that information can be properly anonymised".
Dr Gordon Gancz told Daybreak he had taken all of his patients out of the CARE.DATA scheme because "most people in the country...do not realise that their confidential and private information will be taken directly from GPs computers".
"All the statistics say that prostate cancer is currently the most common cancer among men, it's about as common as breast cancer. Within the next 15-20 years it will be the most common cancer in this country.
"For the majority of the men who have it, they don't have any symptoms. That is the very reason why you need to go to the doctor, particularly when you get close to 50 and see if the test is right for you."
The head of the medical website doctors.net.uk, which conducted the survey, has said that the results show that many doctors see revalidation as an "administrative burden".
GPs and hospital doctors seek to uphold the highest possible standards in care, and their willingness to be totally frank about variations in quality demonstrates how keen they are to see continual monitoring and improvement.
However, while revalidation should help to address such concerns, there is widespread scepticism about its effectiveness.
Many hard-pressed doctors view it as yet another administrative burden. They do not see it as a safety net for identifying any doctors who are not fit to practise or as a benchmark for ensuring that all patients receive the highest possible levels of care and treatment.
– Dr Tim Ringrose, chief executive, doctors.net.uk