This project proposes to measure delay to admission to Intensive Care (ICU). Delays in the United Kingdom NHS are widely reported possibly because there are fewer ICU beds than in many other developed health care systems. Patients are inevitably admitted with more severe illness. Scores measuring this severity are used for research and benchmarking. However, although patients deteriorate over time, severity is probably neither directly nor linearly related to the duration of illness. Instead it is likely that the characteristics of severity change with time. In sepsis there is good biological evidence of this so that there is an early pro-inflammatory stage followed by later changes in metabolic, neuroendocrine, and immune systems. In addition to examining the effect of duration of illness prior to ICU admission, the investigators will also therefore investigate how severity changes over time.