The investigators anticipate that approximately 20,000 patients will be required to provide a sample of up to 2,000 admissions to critical care after surgery. Assuming an overall mortality rate following surgery of 1%, a sample size of 20,000 patients will yield 200 deaths. This will allow the inclusion of at least fifteen variables in a logistic regression model for mortality. The rate of admission to critical care is likely to vary between nations but an overall rate of 10% will yield data describing up to 2000 admissions to critical care, whilst an overall rate of 5% will yield 1000 admissions. This to allow construction of a robust logistic regression model for this outcome. 20,000 patients will also provide >99% confidence for the overall mortality rate with 0.37% confidence width. If 200 deaths are observed in an overall sample of 20,000 patients, the 99% confidence interval for the proportion would be (0.008 - 0.012) with a confidence width of 0.37%. This dataset would also have sufficient generalisability to inform the practice of peri-operative care on an international basis.