Table 2. Correlation Between Early Background Activity, Sleep-Wake Cycling Findings, and Seizures.
| Characteristic | Participants, No. (%) | Odds ratio (95% CI) | ||
|---|---|---|---|---|
| Overall (N = 872) | HIE with seizures (n = 296) | HIE without seizures (n = 576) | ||
| Early background activitya | ||||
| Continuous normal voltage | 373 (42.8) | 53 (17.9) | 320 (55.5) | 1 [Reference] |
| Discontinuous normal voltage | 177 (20.3) | 72 (24.3) | 105 (18.2) | 4.14 (2.73-6.27) |
| Continuous low voltage | 184 (21.1) | 86 (29.1) | 98 (17.1) | 5.30 (3.52-7.96) |
| Burst suppression | 45 (5.2) | 19 (6.4) | 26 (4.5) | 4.41 (2.29-8.50) |
| Flat trace | 85 (9.7) | 58 (19.6) | 27 (4.7) | 12.9 (7.57-22.22) |
| Status epilepticusb | 8 (0.9) | 8 (2.7) | 0 | NA |
| Sleep-wake cyclingc | ||||
| Present | 425 (48.7) | 106 (35.8) | 319 (55.4) | 1 [Reference] |
| Absent | 447 (51.3) | 190 (64.2) | 257 (44.6) | 2.22 (1.67-2.96) |
Abbreviation: HIE, hypoxic-ischemic encephalopathy; NA, not applicable.
a
To assess early background activity, the initial background activity shown in the first 6 hours of life was considered.
b
When status epilepticus was present, background activity was not classified.
c
The presence of sleep-wake cycling and seizures was assessed during the entire monitoring time.