Karnofsky Performance Scale — Functional Status Tool

Developed by Dr David Karnofsky in the 1940s, the scale grades a person's functional capacity on an 11-point continuum ranging from 100% down to 0% in intervals of 10. A score of 100% represents normal physical functioning with no evidence of disease or physical complaints, while a score of 0% indicates death.

The scale is broadly split into three functional tiers. Scores between 80% and 100% describe individuals able to carry on normal activity with minor symptoms; scores of 50% to 70% represent patients unable to work who can live at home but need varying assistance; and scores below 50% denote individuals requiring considerable medical care and hospitalisation.

Performance status is one of the strongest indicators of how well a patient can withstand intensive treatments like chemotherapy, major surgery, or radiotherapy. A robust KPS score reassures oncologists that a patient possesses the physiological reserve to tolerate therapy without experiencing debilitating toxicity. It also helps clinicians recognise when treatments need dose adjustments or when emphasis should shift toward rehabilitative and palliative symptom support.

The KPS does not rely on laboratory biomarkers or imaging scans. Instead, it is assessed during routine clinical consultations through direct physician observation, functional mobility evaluation, and conversations with the patient and their family regarding daily activities, fatigue levels, and personal independence.

The Karnofsky Performance Scale is widely applied across all adult solid tumours and haematological malignancies. It is especially prominent in neuro-oncology (glioblastomas and brain metastases), lung cancer, gastrointestinal malignancies, and palliative care settings where tracking functional trajectory over time is critical for clinical decision-making.

A patient's KPS score directly influences therapeutic strategy. Clinical trials frequently mandate a KPS of 70% or higher for enrollment to ensure participants can tolerate study drugs safely. In daily practice, lower scores may prompt oncologists to select gentler regimens, reduce dosages, or incorporate early palliative support to improve quality of life.