What is Casemix?

The term casemix has a number of meanings, from the literal 'mix of cases (patients)' seen by a consultant/hospital/region, to the way in which patient care and treatments are classified into groups. These groups provide a useful measure on which to make performance comparisons, to cost healthcare, or indeed to fund it.

The principles of the development of a Casemix Classification are well-established internationally and have been since the late 1960s. These are generally accepted to require a casemix classification (often referred to as Casemix Groups) to be:

• clinically meaningful
• relatively similar at the group level, in resource terms
• based on mandated, standardised, and readily available data
• manageable in number

The development, maintenance and evolution of a Casemix Classification requires a combination of established rules and principles, specialist expertise and data. All Casemix designs rely on the availability of national data flows, data definitions and data standards, and the National Casemix Office (NCO) manages a complex interface between each of these in order to develop and improve our service and maintain our status in the national and international arena.

Casemix classifications are underpinned by consistency, empirical evidence, and a clear focus on what we’re trying to do, and why. In its simplest sense, a classification enables the health care system to understand the healthcare activities it undertakes, the type of patients who benefit from such activities and interventions, and the resource use required to deliver optimal patient care.

Casemix is therefore a method of classifying patient care based on expected clinical resource use for the provision of that care. Healthcare Resource Groups (HRGs) are the Casemix Classification within the NHS in England, and are developed and maintained by the NCO, who design and refine the classifications used to describe NHS healthcare activity in England, Since the first versions of our HRG classifications in the early 1990s, there have been various interactions of our casemix design, in order to maintain clinical validity, and reflect changes in clinical practice and technology.

As an impartial, independent body accountable to the NHS, NHS England and Improvement and the Department of Health and Social Care, the remit of the NCO is to develop and enforce national standards underpinning the monitoring, measurement and improvement of healthcare performance at a local, regional and national level. A rigorous and effective casemix currency can make a significant difference to the health service and can be used to provide the basis for delivering local improvements in patient care.