Variability by country in the European Neuroanaesthesia and Critical Care Interest Group subarachnoid haemorrhage survey

Although surveys are common in studies of healthcare, because they are quick and inexpensive, there are considerable limitations. The data are generally descriptive, often incomplete and subject to biased sampling, so it is often difficult to conclude any causal inference.1 The survey of the European Neuroa- naesthesia and Critical Care Interest Group on perio- perative clinical practice in patients with acute subarachnoid haemorrhage is no exception.2 The main result of this study, recently published in the European Journal of Anaesthesiology, highlighted considerable variability in the management of subarachnoid haemor- rhage patients. The factors influencing the variability of subarachnoid haemorrhage treatment by country are, however, still unknown.2