Continuous EEG is associated with favorable hospitalization outcomes for critically ill patients

Abstract

Objective: To characterize continuous EEG (cEEG) use patterns in the critically ill and to determine the association with hospitalization outcomes for specific diagnoses.

Methods: We performed a retrospective cross-sectional study with National Inpatient Sample data from 2004 to 2013. We sampled hospitalized adult patients who received intensive care and then compared patients who underwent cEEG to those who did not. We considered diagnostic subgroups of seizure/status epilepticus, subarachnoid or intracerebral hemorrhage, and altered consciousness. Outcomes were in-hospital mortality, hospitalization cost, and length of stay.

Results: In total, 7,102,399 critically ill patients were identified, of whom 22,728 received cEEG. From 2004 to 2013, the proportion of patients who received cEEG increased from 0.06% (95% confidence interval [CI] 0.03%-0.09%) to 0.80% (95% CI 0.62%-0.98%). While the cEEG cohort appeared more ill, cEEG use was associated with reduced in-hospital mortality after adjustment for patient and hospital characteristics (odds ratio [OR] 0.83, 95% CI 0.75-0.93, p < 0.001). This finding held for the diagnoses of subarachnoid or intracerebral hemorrhage and for altered consciousness but not for the seizure/status epilepticus subgroup. Cost and length of hospitalization were increased for the cEEG cohort (OR 1.17 and OR 1.11, respectively, p < 0.001).

Conclusions: There was a >10-fold increase in cEEG use from 2004 to 2013. However, this procedure may still be underused; cEEG was associated with lower in-hospital mortality but used for only 0.3% of the critically ill population. While administrative claims analysis supports the utility of cEEG for critically ill patients, our findings suggest variable benefit by diagnosis, and investigation with greater clinical detail is warranted.

Figure 1. Study population flow diagram

Application of inclusion and exclusion criteria. cEEG = continuous EEG; NIS = National Inpatient Sample.

Figure 2. Use of cEEG in critically ill discharges from 2004 to 2013 by diagnostic subcategory

Numerator is the number of patients who underwent continuous EEG (cEEG); denominator is the total discharges with a particular diagnosis.

Figure 3. Hospitalization outcomes with cEEG use

The reference group is no continuous EEG (cEEG). CI = confidence interval.

Figure 4. Effect of hospital cEEG volume on in-hospital mortality (2004–2011)

The reference group is low volume. cEEG = continuous EEG; CI = confidence interval.