(Medical Xpress) -- Elderly patients having gallbladder surgery may be more at risk depending on where they are treated.
University researchers who studied 10 years worth of data for gallbladder removal surgery found that patient deaths were generally low.
However the chances of survival for patients considered high risk varied significantly between hospitals.
Patients considered most at-risk of complications included the elderly.
They also included those with other underlying health problems such as heart or chest conditions, and patients from socially deprived areas.
The study showed that mortality rates were 50 per cent higher in hospitals that carried out only a small number of gallbladder removals compared with hospitals that performed many.
For patients considered low risk, the difference between hospitals was negligible.
However, a high-risk patient had a one in five chance of dying at a centre that performed a small number of these operations.
This compared with a one in seven chance of death if treated at a hospital with higher numbers of surgery.
Overall mortality rates for patients, regardless of whether they were high or low risk and where they were treated, was found to be one in 200.
In some hospitals the gallbladder was removed, where possible, following admission.
In other hospitals, gallbladder surgery was delayed and the patient discharged.
The reasons for this variation are not clear.
The findings, which were based on data relating to 60,000 patients treated in 37 Scottish hospitals, could help in making decisions about where patients should be treated.
"While the mortality rate following gallbladder removal is very small, it is increased for certain patients, such as the elderly or those with heart or chest problems. The findings that mortality rates for high risk patients are greater in hospitals that only carry out a small number of gallbladder removals could help to inform where these patients should be treated," said Ewen Harrison, Lecturer in surgery.
Hospitals were classed as having a high volume of patients if they carried out more than 244 operations a year.
They were classed as having a medium volume for between 173 and 244 operations and a low volume if they carried out less than 173 operations a year.
The study has been published by the British Medical Journal.
Gallbladder removal is one of the most common operations in the UK, with around 60,000 performed in the UK each year.
The most common need for surgery is the presence of gallstones in the gallbladder.
These are formed when substances that make up bile - which helps break down fatty food - are out of balance.
Most patients are discharged the same day or the following day after surgery.
Gallbladder removal can either be carried out with keyhole surgery, which is the most common operation performed.
Alternatively the gallbladder can be removed with open surgery, through an incision in the abdomen.