A new report in the New England Journal of Medicine has some troubling findings about surgical safety checklists in Ontario hospitals.

The study suggests the checklists, a frontline tool for avoiding complications in the operating room, are not working as well as expected.

At the London Health Sciences Centre, the list includes ensuring the surgical site has been marked by the surgeon, confirming members the surgical team, and - after the procedure - making sure instruments are accounted for.

The World Health Organization says these lists could save up to 500,000 deaths a year world wide and they were mandated by the Ontario government in 2010.

But the study of Ontario hospitals by Dr. David Urbach at the Institute for Clinical Evaluative Sciences, paints a somewhat different picture.

"After a hospital introduced a surgical safety checklist they did not experience a significant reduction in the risk that patients died after surgery. Nor was there a significant reduction in the risk of patients having complications after their surgery."

The study looked at rates of complications three months before they were implemented and three months following.

As for why there weren't significant improvements given the high rate of checklist compliance hospitals reported, an editorial accompanying the study has some idea.

"The Checklist Condundrum" speculates "The likely reason for the failure of the surgical checklist in Ontario is that it was not actually used. Compliance was undoubtably much lower than the reported 98 per cent."

At LHSC the latest compliance report cites figures of more than 99 per cent and Dr. John Denstedt, chief of surgery, says patients in London and across Ontario should be confident about surgery quality.

"If you look overall in the publication, the complication rate is extremely low. So we're providing a very high quality, high standard of care."

But, he says the hospital is always looking to make improvments.

"The checklist is a tool, frankly. It's what comes out of that tool that is the important point. This publication stimulates us to actually improve how it functions."