The scale of the transfer of NHS staff to independent sector providers in recent years has been revealed in new figures.

At least 17,000 staff, mostly clinical workers, have moved since 2010, according to revised workforce statistics published by Health and Social Care Information Centre.

The organisation, soon to be renamed NHS Digital, said the shift was largely down to transfers prompted by two government policies, both of which particularly affected community services.

The first was the transforming community services initiative, which forced primary care trusts to divest themselves of their provider services, by either joining them with existing trusts, forming independent trusts or social enterprises, or passing them to private providers. Most of these transfers took place in 2011.

The second policy which brought about the shift was “any qualified provider”, which was pushed as a way of opening up some primary and community services to competition by the Department of Health between 2011 and 2013.

In 2010, there were 664 full time equivalent staff registered as working for independent sector providers. The following year, this had more than doubled to 1,807, and by 2015 the number had increased to 17,876.

The HSCIC confirmed the increase reflected staff who had transferred from NHS employment, and that improved data collection was not the main factor behind the increase. The new workforce data collection was published in March

Peter Griffiths, chair of health services research at the University of Southampton, said: “I think that this does clearly show the extent of the transfer into the private sector and is significant.”

He said he was concerned staff shortages could be exacerbated by “the incentive to take a narrow view of the interests of the provider rather than the service as a whole” and “the fragmentation of the NHS into a myriad of private providers with a loose affiliation to the [NHS] ‘brand’”.

Nurses appear to have been most affected by the change, with a 5,938 whole time equivalent increase in the number in the independent sector since 2010, the figures show.

Queens Nursing Institute chief executive Crystal Oldman said staff had experienced some problems moving out of the NHS.

She said: “At the QNI we hear very mixed views about staff experience working for private providers – and concerns about the lack of investment in the development of staff.” For example, there are concerns that some are not being supported to take the district nurse specialist practitioner qualification, which “has been an integral part of postgraduate nursing education for many years”, she said.

The HSCIC believes its workforce data covers most large independent providers, but that many smaller providers are not included. Prior to 2015 it only covered organisations using the electronic staff record.

NHS Partners Network chief executive David Hare told HSJ: “Independent sector providers train thousands of clinical and non-clinical staff every year and this shows up in the high standards of care provided by staff working in the independent sector.

“The sector works hard to ensure that services are coordinated in the best interests of patients and takes a positive and proactive approach to staff development.

“The process of staff transferring to independent sector community services providers has taken place over several years and all the indications are that this has worked well and that staff are fully supported to deliver first rate patient care.”