Case mix, also casemix and patient mix, is a term used within [[healthcare]] as a synonym for [[cohort]]; essentially, a case mix groups statistically related patients.

An example case mix might be male patients under the age of 50, who present with a myocardial infarction and also undergo emergency coronary artery bypass surgery.

At a local level, such as a single hospital; the data within a case mix may relate to the activity of an individual consultant, a specific speciality or a particular unit (such as a ward). On a wider level; it is possible to compare the case mix of hospitals, regions, and even countries.

Whilst a case mix will often include a condition or diagnosis, as well as any treatment received; it can also include demographics, such as gender or age, and a specific time range.

Conditions and treatments are often captured using a medical classification system, such as ICD-10, in a process called clinical coding. The practice of coding, essentially groups patients using statistical codes. The coded data can be grouped further into Diagnosis-Related Groups (DRGs), which are used in the billing process by hospitals and practices; as the "cost per item" of healthcare is based on the casemix.