An analysis of the impact of GP-led health centres - around 250 of which were set up between 2008 and 2012 following a review by Lord Ara Darzi under former prime minister Gordon Brown - found that GP services divert significant numbers of patients away from A&E.
The study found that 'convenience matters' in terms of GP services' impact on A&E. Many of the GP-led health centres operated on a 'walk-in' basis, rather than requiring patients to book appointments.
Researchers writing in the Journal of Health Economics found that these clinics divert three times as many patients as traditional practices away from hospital emergency departments.
However, just five to 20% of patients who attended walk-in centres overall would otherwise have gone to A&E, the researchers said - while some patients who attended these quick-access services would not have visited a doctor at all.
'This poses a dilemma for policymakers,' said study author Dr Edward Pinchbeck. 'Easy access walk-in type services are popular, which tells us they are valued by patients, and they do relieve pressure at over-stretched emergency services.
'But on the flip side, low diversion rates from A&E mean that they may be an expensive way to meet this particular goal. The cold reality of a chilly funding climate points to hard choices in allocating scarce NHS resources to best meet local demand.'
The original plans for rollout of GP-led health centres proposed one centre in each of the then-152 primary care trust (PCT) areas across England - with a further 100 spread across underdoctored areas.
The BMA backed the rollout of services in some areas at the time but warned they were often established in areas with low demand from patients - and said spending on the schemes would have been better directed at boosting existing services.
Access to GP services was highlighted as a priority for the government by Boris Johnson in his first speech as prime minister last year. Mr Johnson promised to 'drastically reduce' waits for GP appointments - and later promised 50m extra appointments a year in general practice by 2024/25.