Full Outline of UnResponsiveness score and Glasgow Coma Scale in medical patients with altered sensorium: Interrater reliability and relation to outcome
Introduction
Assessment of level of consciousness is an important part of clinical neurologic assessment. Glasgow Coma Scale (GCS) has been the most widely used scale for assessment of sensorium [1]. Earlier studies have shown reasonable interobserver reliability of GCS and its predictive value, particularly in head injury and other neurologic disorders [2]. Despite its widespread use, certain limitations of GCS are known. The verbal component of GCS cannot be reliably assessed in patients with aphasia and those with tracheal intubation. Glasgow Coma Scale has been observed to be difficult to use by untrained staff such as nurses and paramedical staff [3]. One study reported difficulty in interpretation of intermediate scores by emergency physicians [4]. Attempts to modify GCS and compare it with other similar scores have been reported [5]. A study by Diringer and Edwards [6] compared GCS with Innsbruck Coma Scale (ICS) and observed that, among 84 patients with various acute neurologic disorders, both scales were best at predicting complete improvement (GCS and ICS, 71% correct) and mortality (GCS, 60% correct; ICS, 56% correct). After deleting verbal score (which had poor discrimination) from GCS, only a modest improvement was noted in its prediction of outcome. They opined that combining clinical scales with other demographic, physiological, functional, and radiographic data would be needed to achieve useful predictions of functional outcome. Certain scoring systems such as Acute Physiology and Chronic Health Evaluation (APACHE), Multiple Organ Dysfunction Score, Sequential Organ Failure Assessment (SOFA) score, and others use several clinical and laboratory parameters; however, these are rather unwieldy for bed-side use and are limited mostly to the intensive care units (ICUs) [7].
On the above background, Wijdicks et al [8], [9] developed the Full Outline of UnResponsiveness (FOUR) score (FS) and compared its performance with GCS. The FS includes 4 components of neurologic evaluation—eye response, motor response, brainstem reflexes, and respiration—each with a scale of 0 to 4. The maximum score possible is 16 and minimum, 0. This scoring system does not include verbal response. The authors observed that FS is easily assessed even in patients who are sedated, intubated, and ventilated; it is able to recognize patients in locked-in syndrome (only vertical eye movements present), possible vegetative state (eyes open but not tracking), and possible brain death.
In a prospective study of 120 patients in the neurologic ICU, interrater reliability was excellent for FS (overall κ statistic = 0.82; 95% confidence interval [CI], 0.77-0.88) and for GCS (κ statistic = 0.82; 95% CI, 0.76-0.87). Patients with the lowest GCS score could be further distinguished using the FS. FOUR score also provided greater neurologic detail than did the GCS, recognizing locked-in syndrome and possible vegetative state. Wijdicks et al [8] also compared the 2 scores for their ability to predict outcome. For FS, every 1-point increase in total score was associated with improved in-hospital mortality by 20% (odds ratio [OR], 0.80; 95% CI, 0.72-0.88), as compared with 26% for GCS (OR, 0.74; 95% CI, 0.65-0.85). The probability of in-hospital mortality was higher for the lowest FS when compared with the lowest total GCS score. Other studies have subsequently reported on the validity of their scoring system by the intensive care nurses, emergency physicians, and medical intensive care physicians and observed good interrater reliability among these groups on nonneurology physicians and nurses [10], [11], [12]. They conclude that FS can easily be used in the general medical ICU and the emergency department with good reliability. FOUR score has been hitherto validated only in few centers other than Mayo hospitals, in the settings of ICU [13], [14], emergency department [15], or neurosurgical patients [16], with similar favorable observations. Recent studies have also demonstrated the correlation of FS with outcome in patients with traumatic brain injury and cardiac arrest [17], [18].
We aimed to compare FS with 2 other scoring systems in use: GCS and SOFA score. The study compared (a) interrater reliability between neurology consultants and internal medicine residents in rating FS and GCS among patients with altered mental status due to medical conditions and (b) the 3 scoring systems in their efficacy in predicting outcomes at hospital discharge and 3 months.
Section snippets
Patients and methods
This prospective, observational study, approved by the ethical and scientific review boards, was conducted for 10 months (January to October 2010). Adult patients 15 years or older admitted to the medical wards or medical high-dependency unit with altered mental status due to any medical cause were recruited into the study, after consent from a family caregiver. Patients with head injury, postsurgery, or current hemodynamic instability (blood pressure [BP] < 80 mm Hg systolic) were excluded.
Results
One hundred patients (male-to-female ratio, 58:42; mean age, 62 ± 17 years) with altered mental status due to a medical condition were studied. Table 1 summarizes their demographic, clinical, and outcome data. Fifty-eight patients had altered mental status due to neurologic conditions; 32, due to metabolic encephalopathy; 21, due to infections; and 7, due to other causes. Range of sensorium and scatter of GCS and FS scores are depicted in Fig 1. Duration of altered mental status ranged from few
At discharge from hospital
At discharge, 69 patients had poor functional outcome (modified Rankin Score [mRS], 4-6), including 24 who died. On univariate analysis (independent-samples t test), the following were significantly related to mortality at discharge: systolic BP (P = .02); GCS—total and all component scores on days 1, 2, and 3 (P < .006); FS—total and all component scores on 3 consecutive days (P < .024); serum creatinine (P = .05); serum albumin (P < .001); hemoglobin (P = .003); and SOFA score (P = .001;
Receiver operating characteristic analysis
Areas under the ROC curve (AUCs) for total scores of GCS and FS from consultants and SOFA scores were comparable for predicting mortality at 3 months (Fig. 2; Table 5). On comparing the performance of component scores, motor scores of both GCS and FS were observed to perform as well as the total scores, whereas GCS verbal scores and FS respiration were noted to have poor performance. Performance of SOFA score was comparable with those of the coma scores.
Discussion
This study compares the interrater reliability of the new FS among neurology consultants and residents with that of GCS among unselected patients with altered mental status managed in general medical wards. Our results suggest that interrater reliability is comparable for FS and GCS, both being in the range of good to excellent [19]. These results are comparable with earlier studies from Mayo Clinics and elsewhere [8], [9], [10], [11], [12], [13], [14], [15], [16]. All the earlier studies have
Conclusion
This study examined the interobserver reliability of FS and GCS among medically ill, adult patients presenting with altered mental status, comparing the performance of neurology consultants with internal medicine residents. The interobserver reliability was comparable for both the coma scores, being in the range of good to excellent. FOUR score performs comparably with GCS but better than SOFA score in predicting outcomes at 3 months. Both consultant- and resident-generated scores were similar
Acknowledgments
This study was funded by the Sultan Qaboos University, Muscat, Oman. The authors wish to acknowledge and thank all the patients and their families for their kind cooperation, Dr Gousia Jikky for help in data collection and maintaining database, residents and SHOs in the Medicine Department for their enthusiastic participation, and nursing staff for their valuable support.
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