A report into the impact of NHS reforms from the Labour government has revealed the proportion of patients seeing their local trust has significantly fallen, while those attending privately-owned centres has risen.

The research was carried out by the Institute for Fiscal Studies and commissioned by the Nuffield Trust in order to determine how the reforms of 2006 and 2008 have changed where care takes place.

The study found that in 2010, most patients still received care from their nearest trust, but GPs were increasingly referring patients to a wider range of providers.

Independent sector treatment centres (ISTCs), privately-owned centres that treat NHS-funded patients, had gone from a “negligible presence” in outpatient care to accounting for 3.5 per cent of all first appointments in 2010-11 - equivalent to almost half a million that year alone.

According to the study, the overall volume of patients seeing all providers has increased since 2006, but there has been a shift away from local trusts and towards private providers.

ISTCs increased their market share of inpatient admissions for a range of operations, with referrals to ISTCs accounting for around half of the change in where GPs refer patients since 2006-07.

The number of hip replacements carried out in local hospitals fell from 68 per cent in 2005-06 to 54 per cent in 2010-11, with privately-owned centres increasing their proportion of the operations.

Elaine Kelly, a research economist at IFS and one of the authors of the report, said: “The use of private providers to treat NHS patients is no longer a marginal policy reform and deserves greater investigation.

“There has been a significant shift in market shares over the past five years from patients’ nearest NHS hospitals to private providers.

“For some procedures, almost one in five NHS-funded operations are now carried out by the private sector.”

The size and speed of this shift varied by operation, with elective unilateral inguinal hernia repair seeing the fastest change - 17 per cent of all patients were seen in an ISTC in 2001-11.

In emergency care, where only trusts provide services, there was hardly any significant change in where patients were treated.

Similarly, the proportion of patients treated in NHS hospitals that were not their closest one barely changed.