The reorganisation of the NHS and increased workload pressures are causing a crisis in the retention of GPs, a new study suggests.
Many doctors are leaving general practice early because of rising bureaucracy and reduced time for patient care.
The authors of the study liken the situation faced by GPs as akin to "boiling frogs" - saying internal and external pressures, as well as a tick box and blame culture, have slowly built up, to a point where for many GPs, continuing is no longer sustainable.
The researchers suggest that in order to buck the trend, and avert a further crisis in GP retention and recruitment for the NHS, the pace of administrative change must be minimised and the time spent by GPs on work that is not face-to-face patient care needs to be reduced.
They suggest that with the cost to UK taxpayers of the five years of postgraduate training for each GP totalling £249,261, there is a real imperative to resolve the challenges faced and to retain these highly-trained professionals within the UK primary care workforce.
The study, which comprised qualitative interviews and an online survey of 143 GPs who had left the profession early, identifies the main issue affecting the decisions of those leaving the profession early as the changing role of general practice.
Of those surveyed, 79% cited unhappiness with day-to-day life as a GP as a significant factor in their decision to leave.
While 55% thought the non-clinical workload was too high, with 84% citing workplace pressures as an additional reason for leaving.
The findings also highlight how nearly half (45.5%) of all GPs leaving the profession in England, between 2009 and 2014, were under 50.
The study, which was carried out by researchers at the Universities of Bath, Bristol and Staffordshire, follows reports that at least 100 GP surgeries have applied to stop taking on new patients, amid claims many are reaching breaking point.
A survey published last April claimed to show a "shocking shortage" of GPs.
GP magazine Pulse said the shortage had led to a 9% vacancy rate in surgeries, up from 6% the previous year.
Lead author Dr Natasha Doran, from the University of Bath, said: "This is not the first time we've witnessed a crisis in GP recruitment and retention but what characterises today's challenge is the number leaving general practice early in their careers.
"An increase in administrative tasks has resulted in less time with patients, compromising the ability to practise more patient-centred care.
"This has impacted on GPs' sense of professional autonomy and values, resulting in reduced job satisfaction, overwork, stress and for many, a higher risk of burnout."
NHS data suggests that since 2008 there has been an additional 40 million patient consultations per year, which are adding to the workload of GPs.
The demand for services in England continues to grow with NHS figures suggesting an estimated 340 million patient consultations per year overall.
Despite this, efforts to encourage more medical graduates to enter GP training have so far fallen short, the authors said.
The Department for Health's target to increase GP training numbers to 3,250 a year has instead remained below this target, at 2,700 GPs a year.
Dr Michael Harris, a former GP and principal investigator on the study, said: "In the last few years I have seen many of my GP colleagues leaving practice early because of the unbearable pressure of work.
"This study has found a key reason is that the constantly increasing administrative workload has reduced the time for the face-to-face patient care that they are passionate about.
"To improve retention of GPs in practice, NHS leaders need to minimise the pace of change and to reduce the amount of time spent by GPs on administrative work."
Co-author Dr Fiona Fox, from the University of Bristol, added: "It is of great concern that the cumulative pressures identified in our study, mean that experienced GPs are being lost to the NHS."
:: The findings are published in the British Journal of General Practice.
Richard Vautrey, deputy chairman of the BMA's GP Committee, said: "General practice is increasingly becoming a stressful environment as GPs are working in a climate of falling funding, rising workload and staff shortages.
"Many are drowning in pointless paperwork which takes them away from what they want to do: treat patients.
"A recent BMA survey found that more than nine in 10 felt their workload is unmanageable and a similar number felt this was negatively impacting on patient care.
"It is unsurprising that there are increasing signs that hard-working GPs are buckling under the pressure and being forced to take a break, a situation which is not only deeply upsetting for the individuals involved, but also reduces the NHS's capacity to provide services to the public.
"There is an urgent need for a proper occupational health service to support the increasing number of GPs suffering from the effects of stress and burnout.
"The Government also need to produce a long-term, sustainable plan for general practice that gives the entire service the resources it needs to deliver the care patients deserve."