ACD Score Proves Valuable in Estimating Long-Term Survival in Status Epilepticus

Christoph Patrick Beier, MD

A novel, simple 3-factor scoring system, called ACD score, was shown to be able to reliably predict long-term outcomes in patients with status epilepticus with causes that were nondamaging or less-damaging to the brain in a recent study. Additionally, the assessment identified that age, long duration, and nonconvulsive type of status epilepticus in coma were associated with the development of new neurological deficits and, in turn, were predictors of long-term mortality.

"We believe that the ACD score has substantial potential to help clinicians make treatment decisions in patients with ongoing and long-standing status epilepticus attributable to remote symptomatic or unknown etiological categories because it predicts both neurological outcome and long-term survival," investigator Christoph Patrick Beier, MD, Department of Clinical Research, University of Southern Denmark and Odense University Hospital, and colleagues wrote, adding that "although the score is associated with 2-year survival in all of the etiological categories they assessed, it has limitations. They wrote that the ACD score is bound “by the obvious impact of, for example, progressive causes and comorbidities in patients with brain-damaging status epilepticus causes."

Although, the investigators explained that the ACD score was perhaps more reliable in those who had cerebral scans without acute changes and no indications of inflammation.

To improve prognostication of long-term mortality after status epilepticus, Roberg and colleagues gathered data from national and local civil registries in Denmark, Norway, and Germany. The exploratory cohort consisted of 261 patients, aged 18 years or older with a diagnosis of status epileptics, which was defined as convulsive seizures longer than 5 minutes, nonconvulsive seizures longer than 10 minutes, and nonconvulsive or possible nonconvulsive status epilepticus shown by EEG.

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Among this full cohort was a subset of 145 patients with status epilepticus causes that were not damaging or were less damaging to the brain. The mean follow-up duration was 2.2 years, and 27 patients had a follow-up of less than 2 years. For all patients, mortality increased nearly 3-fold from the short-term in-hospital rate of 17.6% to the long-term—2 years—rate of 47.1%.

On a logistic regression model, new neurological deficits were associated with progressive central nervous system disorders after adjusting for known prognostic factors (adjusted odds ratio [aOR], 5.1; 95% CI, 2.2-11.8). For patients with National Institutes of Health Stroke Scale (NIHSS) score increase lower than 5 points, investigators documented an 85.2-month (95% CI, 30.0-107.2) estimated median survival whereas those with score increases between 5 and 10 points had estimated median survival of 34.2 months (95% CI, 8.1-60.3). Notably, only a 3.4-month (95% CI, 2.3-4.5) estimated median survival was documented in those with NIHSS scores increase higher than 10 points.

Among individuals who were alive at discharge or follow-up, 29.8% (64 of 215) had developed moderate to severe neurological deficits. NIHSS score increases were found to be correlated with decreased Barthel index (Pearson r = 0.74; P <.001) and increased modified Rankin Scale (mRS) score (Pearson r = 0.58; P <.001). Additionally, mean duration of status epilepticus and nonconvulsive status epilepticus in coma remained associated with change in neurological function in a subset of patients with status epilepticus causes that were not damaging or were less damaging to the brain.

The ACD score was developed out of a LASSO model, which identified 5 prognostic factors—age, duration of status epilepticus, time to diagnosis, treatment in intensive care unit, and level of consciousness at hospital admission—that were included in a factor score. Treatment in the intensive care unit and time to diagnosis were removed after realizing these 2 components contributed only marginally to the total score.

When testing the accuracy of ACD score, the area under of the curve (AUCs) of the preliminary 5-factor score and the ACD score were similar (0.79 [95% CI, 0.73-0.85] vs 0.78 [95% CI, 0.72-0.84]). The optimal cutoff value for the ACD score was 10 points, with a sensitivity of 0.63 and a specificity of 0.82 for being alive without new neurological at first follow-up.

The ACD score was further validated in 2 independent cohorts comprised of patients from Norway (n = 139) and Germany (n = 906). In a subset of patients from all 3 countries (n = 792), an ACD score higher than 10 points was associated with mortality in the Kaplan-Meier analyses in the validation cohorts from Germany and Norway. In the combined cohort, mortality at 2 years after discharge showed an almost linear correlation with the ACD score (Pearson r2 = 0.848). The association was essentially unchanged when using logistic regression or risk difference regression.

REFERENCE
1. Roberg LE, Monsson O, Kristensen SB, et al. Prediction of long-term survival after status epilepticus using the ACD score. JAMA Neurol. Published online April 11, 2022. doi:10.1001/jamaneurol.2022.0609