For example, there are a number of different knee-related procedures that all require similar levels of resource; they may all be assigned to one HRG.
HRG4 is updated annually to enhance the system, reflect changes in clinical practice and to include changes to policy.
The HRG system is used by Payment by Results, an activity based payment system rolled out in the NHS in England (but not Wales) from 2004 and used to determine the income hospitals in England get for given hospital stays and procedures.
[1] HRGs can be derived for the following areas: Patient data are assigned HRG codes using a software application known as a Grouper.
The final letter is known as the 'split' and is used, for example, to indicate the level of complications and comorbidities associated with the HRG (e.g. Minor, Intermediate and Major), for different lengths of stay, ages or a combination of factors.