Women who are operated on by a male surgeon are much more likely to die, experience complications and be readmitted to hospital than when a woman performs the procedure, research reveals.

Women are 15% more liable to suffer a bad outcome, and 32% more likely to die, when a man rather than a woman carries out the surgery, according to a study of 1.3 million patients.

The findings have sparked a debate about the fact that surgery in the UK remains a hugely male-dominated area of medicine and claims that “implicit sex biases” among male surgeons may help explain why women are at such greater risk when they have an operation.

“In our 1.3 million patient sample involving nearly 3,000 surgeons we found that female patients treated by male surgeons had 15% greater odds of worse outcomes than female patients treated by female surgeons,” said Dr Angela Jerath, an associate professor and clinical epidemiologist at the University of Toronto in Canada and a co-author of the findings.

“This result has real-world medical consequences for female patients and manifests itself in more complications, readmissions to hospital and death for females compared with males.

“We have demonstrated in our paper that we are failing some female patients and that some are unnecessarily falling through the cracks with adverse, and sometimes fatal, consequences.”

The findings have been published in the medical journal JAMA Surgery.

Jerath added: “These results are concerning because there should be no sex difference in patient outcomes regardless of the surgeon’s sex.

“On a macro level the results are troubling. When a female surgeon operates, patient outcomes are generally better, particularly for women, even after adjusting for differences in chronic health status, age and other factors, when undergoing the same procedures.

Jerath and her colleagues analysed the records