Each year, there are at least one million unnecessary tests, treatments and procedures done in Canadian health care settings. This means that hundreds of thousands of Canadians are exposed to potential harm by unnecessary care.What constitutes 'unnecessary care'?Unnecessary care could be a prescription drug, a diagnostic test or a medical procedure that does not improve a patient's health outcomes and is not backed by the best available evidence.  It may also involve risks and harmful side-effects.In other words, this is medical care that offers no value to patients and strains health care resources.A recently released report from the Canadian Institute for Health Information (CIHI) in partnership with Choosing Wisely Canada demonstrates how pervasive unnecessary care is across the country and highlights several key examples where changes could be made to benefit patients and the health system.So, what are we better off without?Unnecessary imaging has consequences.The report says about 30 percent of patients visiting Ontario and Alberta emergency departments for minor head injuries have CT scans. CT scans deliver strong x-ray radiation. Exposure to this radiation can increase lifetime cancer risk.  Yet evidence shows there are good alternatives to CT scans for investigating head injuries. For example, doctors can use a set of questions, known as a clinical decision rule, to assess the severity of a head injury and decide if further diagnostic testing is warranted.Unnecessary medications have side-effects.The report estimates that one in 10 Canadian seniors regularly uses sleeping pills, known as benzodiazepines, and other sedative hypnotics, on a regular basis.  The long-term use of these medications outweighs benefits, which is why they are only recommended for short-term use. These medications increase the risk of falls causing injuries and car accidents in seniors.Seniors are not the only population where there is unnecessary and potentially harmful medication use. The report shows a disturbing 300 percent increase in dispensed prescriptions for the powerful antipsychotic quetiapine for insomnia in children and youth in Manitoba, Saskatchewan and British Columbia. This drug is not recommended for children or youth and has a long list of harmful side-effects.An important finding of the report that should cause Canadians to take notice is wide variation across regions and between provinces. Variation means major differences in medical practice, some of which are not evidence-based and can be potentially harmful to patients.Reducing variation improves quality for all Canadian patients and can reduce waste.  A good example of this is pre-operative testing. In Ontario, nearly one in three patients having eye surgery had a preoperative test, compared to one in five in Alberta.Medicine has evolved and so has medical practice. It used to be standard that before certain surgeries, like hip or knee replacements or cataract surgery, pre-operative tests would be done to ensure that a patient was fit for surgery. These tests could include blood work, electrocardiograms and chest x-rays. As surgical techniques and technology have evolved, however, most of these pre-operative tests are no longer needed, unless there is a specific concern.In spite of the pervasiveness of unnecessary care, the picture is not a bleak one. The report also provides several examples of how health care providers are working hard to put in place better practices or protocols to reduce waste, which may also harm patients.We know patients are aware of this problem too. Ipsos Reid survey data shows that one in four Canadians say they personally have experienced unnecessary care in the past year.  67 percent of Canadians surveyed believe patient demand is also responsible for unnecessary care, rather than decisions made by health care providers alone.  Nearly half (42 percent) of Canadians surveyed said they expect a test ordered, or a prescription written, when they visit a doctor's office.But the vast majority (92 percent) of Canadians surveyed also said they need more information to help make decisions and ask the right care questions.So what should patients do?Choosing Wisely Canada, a national, clinician led campaign has four key questions a patient can ask their care provider to help start a conversation about unnecessary care: Do I really need this test, treatment or procedure? What are the downsides? Are there simpler, safer options? What happens if I do nothing?Together with health care providers, Canadians can help reduce unnecessary care by asking questions and having conversations about when more isn't always better.Wendy Levinson, MD, OC is an expert advisor with EvidenceNetwork.ca and the Chair of Choosing Wisely Canada, and a Professor of Medicine at the University of Toronto.