US health care spending could be cut by billions a year if doctors spent the same amount of time and money dealing with insurance plans as their Canadian counterparts, a study found Thursday. Canada has a \"single-payer\" system for health care financing, under which doctors deal with just one paying agency, while American doctors have to interact with their patients\' many different insurance plans. \"If US physicians had administrative costs similar to those of Ontario physicians, the total savings would be approximately $27.6 billion per year,\" said the study led by Dante Morra of the University of Toronto. Because of the multi-layered US system, doctors spend nearly $83,000 per physician per year interacting with multiple insurance companies, compared to around $22,000 for doctors in Ontario, the study found. Staff in US doctors\' offices also spend around 10 times longer per physician per week dealing with health plans than their Canadian counterparts, according to the study by researchers at Cornell University and the University of Toronto. US nursing staff and medical assistants spend around 21 hours a week per doctor dealing with insurance providers compared with around 2.5 hours a week for Canadian nurses and medical practice workers, said the study published in the Health Affairs journal. \"Many factors contribute to the high cost of health care in the United States, but there is broad consensus that administrative costs in the health care system are high and could be reduced,\" the study said. \"Interactions between physician practices and health insurance plans are one prominent component of administrative costs.\" President Barack Obama\'s health reform legislation, which passed after a monumental political effort last year, aimed to expand health coverage to most Americans, cut down on abuses by private insurance giants and cut ballooning costs. But Republicans have branded the law, the most sweeping social legislation for decades, as a government power grab and are challenging it in the courts.