What do you do when you have no evidence?

Evidence based medicine is all well and good, but what should you do when there is no evidence? How might you act differently if the absence of evidence relates to an acute problem, a complex chronic issue or a life-limiting situation? This is even more likely to be an issue when dealing with particular groups of patients. There is often a paucity of evidence when considering treatments or interventions for children and young people. This paper will guide the readers through various levels of absence of evidence, and while it won't be able to tell you what to do, it will give you different ways of looking at the problem.