This study compared the prognostic performance of two SE scores (STESS and EMSE) and four broader critical illness or neurocritical illness scores (INCNS, APACHE-2, SAPS-2, and SOFA) in critically ill patients diagnosed with SE for both mortality and return to baseline functional status. In line with prior evidence [14,15,16], we found that the STESS lacked accuracy for outcome prediction in critically ill patients with SE and that the EMSE was marginally better than the STESS. In seeming contradiction with prior evidence , however, we also found that the APACHE-2 and SAPS-2, as well as their modified versions without the GCS, had better discriminative power for death and functional outcome, respectively, than the STESS. However, none of the investigated scores had sufficient accuracy to be used for clinical decision in isolation at the individual level.
To date, as many as ten prognostic scores have been developed for adult patients with SE: STESS , two modified scores based on STESS (mSTESS  and nSTESS ), EMSE score , ENDIT score , a new score combining STESS and ENDIT , two Thailand scores predicting short- and long-term outcomes based on the national SE database [36, 37], Complication Burden Index (CBI) , and Age Consciousness Duration (ACD) score . STESS and EMSE scores are the most widely used scores for status epilepticus and include quite different parameters. Therefore, we chose STESS and EMSE scores in this study and compared these two most representative SE-specific scores with general illness severity scoring systems.
The STESS was the first severity score and the most widely used score for SE . However, a study about SE in North-American ICU reported an AUC of 0.61 for STESS in predicting in-hospital death , and a study including patients with refractory SE showed an AUC of 0.57 . STESS made false predictions for death in 51.4% of SE patients, and comorbidity was indicated as a risk factor to be considered . Our study also shows that the prognostic performance of STESS was poor for both mortality and no return to baseline status. Although the STESS was previously shown to be as strongly associated with outcomes as critical illness severity scores in ICU patients with SE , our study is the first to assess and compare their respective prognostic accuracy. Compared to this prior study, patients in our study were more severely ill, as attested by higher CCI, APACHE-2, SAPS-2, and SOFA scores and a higher mortality rate, providing a more diverse and possibly more representative cohort of critically ill patients.
There are several versions of EMSE based on different combinations of etiology, comorbidity, level of consciousness, duration, and EEG. EMSE-EACE, including etiology, age, comorbidities, and EEG findings, is the most widely used and most robust version and was investigated in this study. Compared to STESS, the prognostic performance of EMSE was marginally superior. However, it is impossible to obtain an EMSE score on admission as with the STESS score, because some time is needed to determine the SE causes. In the multivariate logistic regression analyses, all the best combinations of scores included at least one or more systemic severity scores. This suggests that while the etiology and preexisting comorbidities assessed by the EMSE-EACE can reflect the vulnerability of SE patients to later multi-organ failures, the assessment of acute systemic complications may provide more accurate information for outcome prediction.
Indeed, without including any parameters specific to SE beyond the GCS, APACHE-2, SAPS-2, and SOFA showed comparable, and in some cases better, prognostic performance than STESS and EMSE. Even the SOFA score, which contains only 6 items for multiple organ (dys)function and is much simpler than other systemic severity scores, achieved a marginally better predictive performance than the STESS for both in-hospital death and no return to baseline condition. After excluding the effect of the GCS, the modified APACHE-2, modified SAPS-2, and modified SOFA still showed a discriminative power greater than the STESS, and comparable to EMSE.
Altogether, these findings indicate that acute systemic comorbidities affect outcome in this population, explaining why STESS and, to a lesser extent, EMSE-EACE are insufficient for outcome prediction for critically ill patients with SE. Systemic severity scores should thus be considered for outcome prediction for critically ill patients with SE, both for clinical and research purposes.
However, none of the scores, be they SE-specific or systemic, had sufficient prognostic power (all AUC < 0.75) when used in isolation. For specificity close to 90%, the sensitivity of all these scores with the respective cutoff values was very low (all < 40%). They are thus not sufficiently reliable to make clinical decisions on limitations of treatment or guide the design of clinical studies. Further studies should thus investigate how best to combine these scores or aim to develop new, more comprehensive, scores for SE patients in ICU.
The study is limited by its retrospective design, although patients were prospectively identified and collected data were readily available from the medical records. The single-center design is also a limitation to the generalizability of our findings, and more prospective multi-centric studies should be conducted to validate these findings. Also, as stated above, we included a cohort of severely ill patients. In addition, lack of return to baseline functional status may not be a precise indicator of the impact of SE and we analyzed it only for the sake of comparison with prior studies. A patient whose mRS score remains stable at 3 is still more severely impaired than a patient whose mRS score rises from 0 to 1, and a patient with a stable mRS score of 3 may also have a significant decline in functional status.