The FOUR (Full Outline of UnResponsiveness) score was developed at the Mayo Clinic to address limitations of the Glasgow Coma Scale in critically ill and intubated patients by grading eye, motor, brainstem and respiratory responses on a 0–4 scale.

Study	Setting and cohort	Key findings
Wijdicks et al. 2005 (Ann Neurol)	120 adults in a neurological–neurosurgical intensive care unit; examinations by neuroscience nurses, neurology residents and neurointensivists.	Showed excellent interrater reliability (weighted κ around 0.8), with 21% in-hospital mortality and 60% poor functional outcome (modified Rankin Scale ≥3). Each 1-point increase in FOUR score was associated with a substantial reduction in the odds of death and poor outcome, and lowest FOUR scores discriminated mortality better than lowest Glasgow Coma Scale (GCS) scores.
Stead et al. 2009 (Neurocrit Care)	69 emergency department patients with acute neurological presentations, scored by emergency physicians, residents and nurses.	Confirmed excellent interrater reliability comparable to the GCS, and showed that both scores predicted in-hospital survival and functional outcome, with the additional neurological detail in FOUR helpful for emergency department triage and management.
Subsequent validation studies	Medical intensive care units, neurosurgical units, stroke cohorts and translated versions in other languages.	Generally report high interrater reliability, close correlation with the GCS and good prediction of mortality or functional outcome across diverse settings, supporting FOUR as a pragmatic alternative coma scale.

The score is particularly helpful when the verbal component of the GCS cannot be assessed (for example, in intubated or aphasic patients) and for distinguishing patterns such as locked-in syndrome, vegetative state and stages of brainstem herniation. Use local neuroprognostication guidance when applying FOUR to discussions about long-term outcome or limits of treatment, and interpret scores cautiously when sedation, neuromuscular blockade or primary respiratory disease may be affecting the examination.

FOUR (Full Outline of UnResponsiveness) Score