Unfortunately, some older people develop frailty due to worsening health and weakened health reserves. Specialist care can improve outcomes for frail older adults, but this may be difficult to prioritise in busy hospitals. Despite this, many markers of frailty such walking difficulties and memory problems are routinely noted in hospital records. These can be grouped into a summary score called a frailty index, to help identify patients at risk. In this study, we will test the value of a frailty index score recently implemented in the Royal Infirmary of Edinburgh. We will do this by seeing if it has identified people at risk of deteriorating health, hospital readmission or death. We will also see if adding further information about patients’ health conditions, medications and blood results could improve the frailty index further. We aim to maximise the value of information already collected in hospitals to prioritise good care for older people.