The study, published in the BJGP, found that the actual cost of placing a medical student in general practice for a 37-week academic year was £40,700, similar to the cost of teaching undergraduates in secondary care. However the average payment rate received by practices was just £22,000 per year.
The researchers said that 'more realistic and equitable' funding was urgently needed or practices would no longer be prepared to teach medical students, which would have 'serious consequences for the NHS workforce'.
The authors highlighted that previous studies had shown a 'significant association between the quantity of authentic clinical general practice teaching at each medical school and the percentage of its graduates who entered GP training after their foundation programme'.
'Although most GPs do recognise the importance of medical students gaining experience in primary care, their willingness and ability to offer placements is already being squeezed by increasing service demands, staff shortage and large increasses in postgradute training,' the researchers added.
They said that if under-resourcing of undergraduate placements continued it was 'inevitable' that there would be further attrition of training places in general practice for medical students.
The study, which collected data from 49 teaching practices and 25 medical schools in England, is the first detailed estimate of the cost of undergraduate education in general practice.
The researchers developed a comprehensive survey tool that looked at the costs incurred by practices, inlcuding the cost of actual teaching, the productivity loss caused by teaching, administration and other overheads, including training practic staff.
The study was commissioned by the Primary Care Education Working Group, which includes representatives from Health Education England, the Society for Academic Primary Care, RCGP, BMA, Medical Schools Council and Committee of General Practice Education Directors, with the aim of supporting the development of a new tariff for undgraduate primary care education.
A standard national tariff for undergraduate teaching in hospitals was introduced in 2013, but funding for medical student placements in general practice is agreed locally between Health Education England and individual medical schools.
Payments to practices continue to be based on a historic NHS payment system that was first introduced in 1976 and is 'widely regarded as outdated, inequitable and in need of urgent review,' the researchers said.
Lead researcher Professor Joe Rosenthal, professor of primary care education at University College London, said: 'This study confirms that the funding currently available to GP undergraduate placement providers is far below the cost to the practice, and also far below the payment available to hospital placement providers. A more realistic and equitable tariff for primary care education funding is needed as a matter of urgency.’