Comparison of APACHE II, MEES and Glasgow Coma Scale in patients with nontraumatic coma for prediction of mortality

Abstract

There are numerous prehosital descriptive scoring systems, and it is uncertain whether they are efficient in assessing of the severity of illness and whether they have a prognostic role in the estimation of the illness outcome (in comparison with that of the prognostic scoring system Acute Physiology and Chronic Health Evaluation [APACHE] II). The purpose of the present study was to assess the value of the various scoring systems in predicting outcome in nontraumatic coma patients and to evaluate the importance of mental status measurement in relation to outcome. < 0.05 was considered statistically significant. For prediction of mortality, the best cutoff points were 19 for APACHE II, 18 for MEES and 5 for GCS. The best cutoffs for the Youden index were 0.63 for APACHE II, 0.61 for MEES and 0.65 for GCS. The correct prediction of outcome was achieved in 79.9% for APACHE II, 78.3% for MEES and 81.9% for GCS. The area under the ROC curve (mean ± standard error) was 0.86 ± 0.02 for APACHE II, 0.84 ± 0.06 for MEES and 0.88 ± 0.03 for GCS. There were no statistically significant differences among APACHE II, MEES and GCS scores in terms of correct prediction of outcome, Youden index or area under ROC curve. APACHE II is not much better than prehospital descriptive scoring systems (MEES and GCS). APACHE II and MEES should not replace GCS in assessment of illness severity or in prediction of mortality in nontraumatic coma. For the assessment of mortality, the GCS score provides the best indicator for these patients (simplicity, less time-consuming and effective in an emergency situation.

Introduction:

There are numerous prehosital descriptive scoring systems, and it is uncertain whether they are efficient in assessing of the severity of illness and whether they have a prognostic role in the estimation of the illness outcome (in comparison with that of the prognostic scoring system Acute Physiology and Chronic Health Evaluation [APACHE] II). The purpose of the present study was to assess the value of the various scoring systems in predicting outcome in nontraumatic coma patients and to evaluate the importance of mental status measurement in relation to outcome.

Patients and methods:

< 0.05 was considered statistically significant.

Results:

For prediction of mortality, the best cutoff points were 19 for APACHE II, 18 for MEES and 5 for GCS. The best cutoffs for the Youden index were 0.63 for APACHE II, 0.61 for MEES and 0.65 for GCS. The correct prediction of outcome was achieved in 79.9% for APACHE II, 78.3% for MEES and 81.9% for GCS. The area under the ROC curve (mean ± standard error) was 0.86 ± 0.02 for APACHE II, 0.84 ± 0.06 for MEES and 0.88 ± 0.03 for GCS. There were no statistically significant differences among APACHE II, MEES and GCS scores in terms of correct prediction of outcome, Youden index or area under ROC curve.

Conclusions:

APACHE II is not much better than prehospital descriptive scoring systems (MEES and GCS). APACHE II and MEES should not replace GCS in assessment of illness severity or in prediction of mortality in nontraumatic coma. For the assessment of mortality, the GCS score provides the best indicator for these patients (simplicity, less time-consuming and effective in an emergency situation.

Introduction

].

]. In theory, the prognostic APACHE II and the descriptive MEES scoring systems are more relevant to prediction of outcome in critically ill patients because the GCS assessment is included in these systems. On the basis of other parameters (arterial pressure, heart rate, respiratory rate, oxygenation, chronic health points, age points), the MEES (descriptive) and APACHE II (prognostic) systems should be better than the GCS at predicting outcomes.

The purpose of the present study was to assess the value of scoring systems in predicting outcome in nontraumatic coma patients and to evaluate the importance of mental status measurement in relation to outcome.

Patients and methods

This prospective study was undertaken over a 2-year period, and included 286 consecutive patients hospitalized for nontraumatic coma. The inclusion criteria were GCS ≤ 9, and specific medical diagnoses as follows: hypoxic or ischaemic injury; focal cerebral injury; general cerebral injury; metabolic or septic encephalopathy; and drug-induced coma or toxic injury, including drug overdose and coma persisting 24 h after discontinuation of toxic substances.

].

< 0.05 was considered statistically significant. Values are expressed as mean ± standard error.

Results

.

.

). There were no statistically significant differences in the correct prediction of outcome, Youden index or area under the ROC curve among APACHE II, MEES and GCS for hospital mortality.

Discussion

]. The need for such evaluation scales is particularly evident in coma patients, and even more so in patients with alterations in consciousness. The aim of research in this area is to obtain a reliable and sensitive scale.

], but later it became widely used in evaluating central nervous system lesions and state of consciousness.

] concluded that, for head-injured patients, the GCS has good predictive value for hospital mortality in comparison with other evaluation scales. The latter scale has also attracted attention because of its simplicity.

] identified a correlation between intracranial pressure, analyses of evoked potentials and GCS score, regardless of aetiology of coma. Those investigators also concluded that GCS is a good prognostication tool, as compared with other, more complicated methods.

]. No statistically significant differences in accuracy of prognosis prediction were identified for the three scales assessed. For prehospital work, this finding is important because it shows that GCS does not deviate significantly either from the MEES scale (which has more parameters) or from the APACHE II scale (which is measured in hospital). GCS has important advantages over other scales, because it enables rapid evaluation of status and may direct necessary interventions. Furthermore, it is possible to observe continuously the state of consciousness, and to identify eventual improvement (indicating efficacy of therapy) or deterioration. GCS is widespread and clinicians are familiar with it. This scale therefore facilitates good 'clinical communication' between prehospital work and further hospital procedures and treatments.

The GCS values determined before hospitalization of the patients and the APACHE II scores determined on the first day of hospitalization enabled us to compare descriptive and prognostic scales directly. We compared the prognostic value of postintervention prehospital values of GCS and hospital values of APACHE II. We found that the prehospital GCS assessment was as good a predictor of mortality as was the APACHE II score, as measured in the hospital. The GCS is well established, and its simple application before admission to hospital and during hospital treatment facilitates continuous evaluation of the patient's state and allows prognostic evaluation in non-traumatic coma.

Figures and Tables

Distribution of patients by APACHE II, MEES and GCS scores.

ROC curves drawn at different cutoff values for APACHE II, MEES and GCS. The area under the curve for GCS is largest, but there is no statistically significant difference when compared with APACHE II and MEES.

Mainz emergency evaluation score

The maximum score is 28; the minimum is 10. SVES, supraventricular premature contractions; VES, premature ventricular contractions.

Outcomes after nontraumatic coma and coma aetiology

Comparison of the assessment scores in hospital mortality

= 0.90 versus MEES.

Keywords

• Acute Physiology and Chronic Health Evaluation II
• Glasgow Coma Scale
• Mainz Emergency Evaluation System
• nontraumatic coma
• prediction of mortality