The NHS in Leeds is set to spend £28m this year on private healthcare.
More patients are choosing to be treated at private hospitals, which has put NHS Leeds £600,000 over budget on its spending on non-NHS care.
However, health bosses in the city say they are committed to giving patients a choice.
A spokeswoman for NHS Leeds said: “We do not have information on the exact reasons why more people are choosing some providers over others this year but we continue to be committed to offering this choice to them.”
NHS Leeds organises and pays for healthcare for city residents with its £1bn budget.
It holds contracts with hospitals in the region to provide treatment, including at some private hospitals. In the financial year 2010-11, £29.1m was spent on care at non-NHS facilities.
Now health managers say more people are opting to have planned care at private hospitals.
Under the NHS constitution, patients being referred for most treatments can choose where to be seen – including at private hospitals if possible. The cost to the health service for private care is the same as at NHS hospitals.
According to bosses at NHS Leeds, recently more patients have chosen to be referred to non-NHS providers.
Spire Hospitals are treating more patients than planned, especially in trauma and orthopaedics, as have Nuffield Hospital which is also seeing more gynaecology patients than expected. Between April and next March, NHS Leeds had budgeted to spend £27.5m on non-NHS care.
But latest figures, up to September, show that already £600,000 more than planned has gone towards private treatment. That means the cost is likely to rise to £28.2m during this financial year.
The NHS Leeds spokeswoman said patient choice was the sole reason for this – but added that they fully supported patients’ rights. She said: “Offering a variety of places where people can have their treatment is part of the NHS Constitution and something which we are really committed to in Leeds.
“People choose where to have their care for all sorts of reasons. They may want to be closer to relatives, prefer the facilities available at one hospital more than another or be influenced by waiting times for treatment.”
Patient choice is not available for emergency treatment, maternity or mental health services or for those referred to cancer services or a chest pain clinic within the maximum two-week waiting times.
Some patients already on waiting lists for care at Leeds hospitals have also been offered care in the private sector as hospital managers battle to cut waits.
For example, some Leeds neurosurgery patients are being seen at a Sheffield hospital.