Validity of the FOUR Score Coma Scale in the Medical Intensive Care Unit

OBJECTIVE: To evaluate the validity of the FOUR (Full Outline of UnResponsiveness) score (ranging from 0 to 16), a new coma scale consisting of 4 components (eye response, motor response, brainstem reflexes, and respiration pattern), when used by the staff members of a medical intensive care unit (ICU).PATIENTS AND METHODS: This interobserver agreement study prospectively evaluated the use of the FOUR score to describe the condition of 100 critically ill patients from May 1, 2007, to April 30, 2008. We compared the FOUR score to the Glasgow Coma Scale (GCS) score. For each patient, the FOUR score and the GCS score were determined by a randomly selected staff pair (nurse/fellow, nurse/consultant, fellow/fellow, or fellow/consultant). Pair wise weighted κ values were calculated for both scores for each observer pair.RESULTS: The interrater agreement with the FOUR score was excellent (weighted κ: eye response, 0.96; motor response, 0.97; brainstem reflex, 0.98; respiration pattern, 1.00) and similar to that obtained with the GCS (weighted κ: eye response, 0.96; motor response, 0.97; verbal response, 0.98). In terms of the predictive power for poor neurologic outcome (Modified Rankin Scale score, 3-6), the area under the receiver operating characteristic curve was 0.75 for the FOUR score and 0.76 for the GCS score. The mortality rate for patients with the lowest FOUR score of 0 (89%) was higher than that for patients with the lowest GCS score of 3 (71%).CONCLUSION: The interrater agreement of FOUR score results was excellent among medical intensivists. In contrast to the GCS, all components of the FOUR score can be rated even when patients have undergone intubation. The FOUR score is a good predictor of the prognosis of critically ill patients and has important advantages over the GCS in the ICU setting.FOUR = Full Outline of UnResponsiveness; GCS = Glasgow Coma Scale; ICU = intensive care unitAssessing impaired consciousness in the medical and surgical intensive care unit (ICU) is very difficult. The complexity of such an assessment relates in part to the difficulty of finding usable terminology, as illustrated in an earlier study in which 3 observers variously described a single patient as “somnolent,” “difficult to arouse,” and “deeply comatose.”¹ In recognition of this problem, Teasdale and Jennett¹ devised the Glasgow Coma Scale (GCS) in 1974 in an attempt to bring uniformity to the clinical examination and to clinical communication about the level of consciousness.The GCS has become a fixture in the initial assessment of abnormal consciousness but is not designed to capture distinct details of the neurologic examination. The GCS has been routinely used in medical and surgical ICUs and is commonly used in the Acute Physiology and Chronic Health Evaluation (APACHE) scoring system. However, its reliability in predicting patient outcomes is unsatisfactory, particularly with regard to the verbal component.² Other investigators have found additional shortcomings of the GCS and have suggested that adding measures of brainstem reflexes to the GCS could provide better prognostic information.³ Rowley and Fielding⁴ found that the reliability of the GCS increases with the experience of its users and that user inexperience is associated with a high rate of errors.We have developed a new coma scale, the Full Outline of UnResponsiveness (FOUR) score. Although the FOUR score is based on the bare minimum of tests necessary for assessing a patient with altered consciousness, it includes much important information that is not assessed by the GCS, including measurement of brainstem reflexes; determination of eye opening, blinking, and tracking; a broad spectrum of motor responses; and the presence of abnormal breath rhythms and a respiratory drive. Because the FOUR score, unlike the GCS, does not include an assessment of verbal response, it is more useful for assessing critically ill patients who have undergone intubation.The FOUR score was originally tested with staff members of a neuroscience ICU⁵ and has been subsequently validated by tests with experienced and inexperienced neuroscience ICU nurses.⁶ To determine whether the FOUR score is equally suited for use by intensivists, fellows, residents, and nurses without a neuroscience background, we prospectively tested the validity of the FOUR score coma scale when used by staff members of a medical ICU.