Mortality prediction by bispectral electroencephalography among 502 patients: its role in dementia

Abstract

Complications of delirium and dementia increase mortality; however, it is difficult to diagnose delirium accurately, especially among dementia patients. The bispectral electroencephalography score can detect delirium and predict mortality in elderly patients. We aimed to develop an efficient and reliable bispectral electroencephalography device for high-throughput screening. We also hypothesized that bispectral electroencephalography score can predict mortality among dementia patients. A prospective cohort study was conducted between January 2016 and December 2018 to measure bispectral electroencephalography from elderly patients and correlate with outcomes. A total of 502 elderly (55 years old or older) patients with and without dementia were enrolled. For a replication of the utility of bispectral electroencephalography, mortalities between bispectral electroencephalography-positive and bispectral electroencephalography-negative group were compared. In addition, patients with and without dementia status were added to examine the utility of bispectral electroencephalography among dementia patients. The mortality within 180 days in the bispectral electroencephalography-positive group was higher than that of the bispectral electroencephalography-negative group in both the replication and the total cohorts. Mortality of those in the bispectral electroencephalography-positive group showed a dose-dependent increase in both cohorts. When the dementia patients showed bispectral electroencephalography positive, their mortality was significantly higher than those with dementia but who were bispectral electroencephalography-negative. Mortality within 30 days in the bispectral electroencephalography-positive group was significantly higher than that of the bispectral electroencephalography-negative group. The utility of the bispectral electroencephalography to predict mortality among large sample of 502 elderly patients was shown. The bispectral electroencephalography score can predict mortality among elderly patients in general, and even among dementia patients, as soon as 30 days.

Keywords: BSEEG; bispectral electroencephalogram; delirium; dementia; mortality.

Graphical Abstract

Figure 1

Survival curve in 180 days based on the BSEEG category. (A) Two BSEEG categories in 228 subjects (replication cohort). (B) Three BSEEG categories in 228 subjects (replication cohort). (C) Two BSEEG categories in 502 subjects (discovery and replication cohorts). (D) Three BSEEG categories in 502 subjects (discovery and replication cohorts). BSEEG, bispectral electroencephalography; B (-), BSEEG-negative; B (+), BSEEG-positive.

Figure 2

Survival curve in 180 days based on the dementia and BSEEG categories. BSEEG, bispectral electroencephalography; B (-), BSEEG-negative; B (+), BSEEG-positive; D (-), Dementia Negative; D (+), Dementia Positive.

Figure 3

Short-term mortality based on the BSEEG category in 502 subjects (discovery and replication cohorts). (A) Thirty days; (B) 60 days; and (C) 90 days. Notes: *Relative risk was significantly higher than those in the BSEEG-negative group. BSEEG, bispectral electroencephalography.