LONDON (AP) -- Doctors who are atheist or agnostic are twice as likely to make decisions that could end the lives of their terminally ill patients, compared to doctors who are very religious, according to a new study in Britain.

Dr. Clive Seale, a professor at Barts and the London School of Medicine and Dentistry, conducted a random mail survey of more than 3,700 doctors across Britain, of whom 2,923 reported on how they took care of their last terminal patient.

Many of the doctors surveyed were neurologists, doctors specializing in the care of the elderly, and palliative care, though other specialists like family doctors, were also included.

Doctors who described themselves as "extremely" or "very nonreligious" were nearly twice as likely to report having made decisions like providing continuous deep sedation, which could accelerate a patient's death.

To ensure doctors are acting in accordance with their patients' wishes, Seale wrote that "nonreligious doctors should confess their predilections to their patients."

Seale also found that doctors who were religious were much less likely to have talked about end of life treatment decisions with their patients.

According to guidelines from the British Medical Association, doctors must not allow their religious beliefs to interfere with their treatment of patients.

"Whatever your personal beliefs may be...you must be respectful of the patient's dignity and views," the association says.

The guidelines also recommend that when patients are unable to communicate their wishes, doctors must not simply rely on their own values, but that they "should take all reasonable steps to maximize the patient's ability to participate in the decision-making process."

The study was paid for by Britain's National Council for Palliative Care and was published online Thursday in the Journal of Medical Ethics.

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