Diagnosing the problem with locum doctors
How safe are we in the hands of locum staff at NHS hospitals?
A shortage of doctors across the NHS has resulted in more shifts being filled by medics on locum contracts. The latest year-on-year figures show a 4% increase in locums working in acute hospitals and community health.
But an investigation by the BBC raises troubling questions about the risks an over-reliance on locums poses to patient safety.
Figures from the General Medical Council (GMC) show that in the three-year period to 2013, locums working in the acute sector - mainly in district hospitals - were attracting almost twice as many complaints as staff doctors. That amounted to more than 250 locums being complained about.
The majority of those complaints result in a formal investigation.
"I do not want to demonise locums," the GMC's chief executive, Niall Dickson, told the BBC. "Lots of good doctors are doing lots of good locum work."
But "locum work does attract risk," he added. "It is risky in the sense that the doctor may not know enough about the hospital where he or she is working.
"It is risky in the sense that they may be brought in when the team is under considerable pressure, and it is risky in the sense that there may be some locum doctors who find it more difficult to find a permanent job.
"So it is an area where we have some concerns."
Many locums are employed through medical recruitment agencies. It's a fast-paced business where staff have to be found - sometimes at short notice - to cover for absences and busy periods.
The GMC says employers have to do more to verify the qualifications and competence of the locums they take on.
In the summer, a court case highlighted concerns that some NHS trusts and agencies were not doing the most basic pre-employment checks.
Levon Mkhitarian was jailed for six years after impersonating a doctor. He'd worked as a locum in A&E departments, cardiology and cancer wards across south London and Kent for almost two years before finally being caught.
He used a false passport and other forged documents to assume a legitimate doctor's identity. The recruitment agency that placed him in work failed to inspect the original documents - relying instead on photocopies, which masked the fact that had "cut and pasted" them together.
It's estimated he dealt with more than 3,000 patients - although there was no evidence that he had harmed anyone.
Mkhitarian - who had a medical degree but had failed to complete his practical training - was eventually caught when a hospital security check revealed another doctor with the same details.
Mkhitarian had a history of using deception to get locum work. Back in 2010, he obtained provisional registration with the GMC, which allowed him to work with very close supervision.
He applied, and got, locum work requiring doctors with full registration - and that went on for three years because no-one was doing the simple check on his registration status.
When the GMC discovered he had lied about his registration, he was struck off. At that point, he stole a legitimate doctor's identity.
For Mr Dickson, the Mkhitarian case stands as a stark reminder to vet doctors before they get on to the wards.
"If someone turns up brandishing a GMC number - that does not mean they're fit to practice," he said.
"A GMC stamp is not good enough for anyone to say, 'Oh, that's alright - I don't need to do anything.' There are responsibilities that agencies, and responsibilities that employers, have."
The regulator has now introduced a system of revalidation - requiring the performance of all doctors, including locums, to be regularly assessed.
Kevin Green, chief executive of the trade group representing medical recruitment agencies, the Recruitment and Employment Confederation, said agencies strived to ensure only appropriately qualified people were employed - and were often the first to spot problems.
"Normally it is the agencies that do spot these issues and flag them up to the GMC, because agencies aren't there to provide staff without the qualifications," he said.
"They want to have a long-term relationship with the NHS and the trusts they support, and they want to make sure the doctors that they put in are qualified and have the right competency.
"We've taken the references, and it is not in [the agencies'] interest to provide someone who has deceived them and gone through the process of trying to falsify their records to get work in the NHS."
The Department for Health said: "We want the NHS to be the safest healthcare system in the world and we expect all employers to carry out appropriate pre-employment checks to make sure their doctors are fit to provide safe patient care."