Some CCGs have tightened the thresholds for access to "low priority" surgery such as hernia and joint problems, while others have introduced new systems to restrict the flow of patients being sent to hospital.
The BMJ's investigation also found that only four of England's 211 new GP led organisations, which assumed statutory responsibility for commissioning around £60bn of NHS care on 1 April 2013, have adopted new guidelines to help widen access to IVF treatment. This has led to disparities in availability across England.
A few CCGs have removed referral restrictions and are relying on better communication between primary and secondary care doctors to drive down costs, but today's investigation has reopened the debate about the role doctors are playing in rationing care in the new NHS - and how this conflicts with their role as patient advocates.
It also raises the question of whether the government, in collaboration with the medical profession and the public, should draw up a list of core services for the NHS to avoid a postcode lottery.
Jerry Luke, a GP in Crawley, West Sussex, recently resigned as clinical director of NHS Crawley CCG partly because of his concerns over rationing. He believes GPs have been placed in an invidious position and warned that CCGs could start running out of money later this year.
CCG leaders told the BMJ that all changes and new policies on whether to refer patients were primarily driven by clinical evidence and best practice and not by finance. NHS England also said it had a process in place to ensure that CCGs delivered their "statutory duties in relation to quality of services."
But the Royal College of Surgeons has argued that many of the procedures deemed of low value have been proved to be effective in preventing complications later in patients' lives.
The BMJ's investigation found numerous examples of CCGs tightening criteria for referral. For example, NHS Mid Essex CCG ratified a host of changes in March 2013 including a new policy for restricting hernia surgery.
Elsewhere, NHS North East Hampshire and Farnham CCG have added a new restriction for treatment of skin lesions, while five other CCGs in Hampshire have altered criteria for bunions and ear grommets.
Eight CCGs across northwest London added new restrictions for nasal surgery and a new general cosmetic policy, but also removed restrictions for several procedures including asymptomatic gall stones, caesarean section for non-medical reasons, and erectile dysfunction drug treatment.
Other CCGs have implemented new referral gateways to try to restrict the number of patients being sent to hospital. A joint system put in place by NHS Chorley and Ribble CCG and NHS Greater Preston CCG will process all GP referrals, and is projected to save almost £50,000 across the two areas. And a new gateway covering all musculoskeletal referrals across two CCGs in Staffordshire is targeting reductions of 209 cases a year in NHS Stafford and Surrounds CCG (designed to save £214,203) and 198 in NHS Cannock Chase CCG (designed to save £209 300).
Some doctors believe that it should be up to NHS England to set national thresholds to ensure consistency. And last month, BMA members called for a debate with the public and the health professions about how the health service they want in the future could be delivered "in a climate of shrinking resources."
But NHS England said CCGs were responsible for explaining the reasons for their commissioning decisions, and said it would not mediate in cases where local clinicians disagreed on whether a treatment was cost effective.
Source: BMJ-British Medical Journal