WHO Performance status classification categorises patients into different groups dependent on their physical fitness and is used to categorise their suitability for chemotherapy.

Chemotherapy as a treatment is not without its side effects, which can limit quality of life and have negative impacts on other comorbidities. Patients will begin to experience significant side effects from chemotherapy once they are at or below a performance status of 2.

The WHO performance status classification categorises patients as:

• 0: able to carry out all normal activity without restriction
• 1: restricted in strenuous activity but ambulatory and able to carry out light work
• 2: ambulatory and capable of all self-care but unable to carry out any work activities; up and about more than 50% of waking hours
• 3: symptomatic and in a chair or in bed for greater than 50% of the day but not bedridden
• 4: completely disabled; cannot carry out any self-care; totally confined to bed or chair.