Criteria for admission to the ICU and scoring systems for severity of illness

Surgical patients comprise 60–70% of admissions to ICUs in the UK. There is significant and increasing pressure on level-2 (HDU) and level-3 (ITU) beds. Guidelines on admission to Critical Care Units include the principles of admitting patients who will benefit from such care and the involvement of senior clinicians at an early stage; but the guidelines are vague. An assessment tool that predicts who would benefit from admission may be useful. Scoring systems are available, but they predict outcome only for cohorts of patients already admitted to Critical Care Units, not those who could benefit from admission.Critically ill patients must be identified as early as possible to allow prompt diagnosis and treatment. Critical Care Outreach Teams have recently been introduced to help identify such patients—they may use early warning scoring systems to guide them.Scoring systems involve gathering information about current physiology and other data (e.g. premorbid diseases). They are most widely used for comparative audit, allowing Critical Care Units to compare their outcomes with others, and track their outcomes over time. They may be useful in research and in resource allocation, but are controversial because many important factors may influence the final score and mask the outcome implications of the score.