Illustration of the prognostic electroencephalographic variables (x-axis) that were investigated in the included studies to predict various outcomes (y-axis). The scatter of points reveals the heterogeneity among the studies, with a maximum of 3 studies sharing the same coordinates. In meta-analyses, we investigated the encircled studies. aEvaluated by Tsumori–Inage Infant Developmental Scale/Questionnaire or Kyoto Scale of Psychological Development. bEvaluated by neurologic examination. cEvaluated by BSID-II. dEvaluated by BSID-II and Peabody Developmental Motor Scales–2. eEvaluated by Denver-II test. fEvaluated by various neurodevelopmental examinations.
Bias risk summary of included studies according to QUIPS. *Authors contributed essential information to accommodate our inclusion criteria. The supplement of nonpublished data was taken into account in assessing the risk of bias.
A, Forest plot of a priori defined cutoff values. If binary divisions for normality and abnormality were made in a study with regard to aEEG, EEG, and outcome, these data were used in the analysis. Otherwise, the authors agreed on cutoff values before the examination of data. FN, false-negative; FP, false-positive; TN, true-negative; TP, true-positive. B, SROC plot of a priori defined cutoff values. The studies are presented as rectangles whose size corresponds to the sample size of the particular study. The height of the rectangle corresponds to the number of diseased, and the width of the rectangle corresponds to the number of nondiseased.
A, Forest plot and B, SROC plot depicting the prognostic accuracy of a mildly, moderately, or severely abnormal aEEG for prediction of a developmental quotient <70 points, cerebral palsy, or death. FN, false-negative; FP, false-positive; TN, true-negative; TP, true-positive.
A, Forest plot and B, SROC plot depicting the prognostic accuracy of a mildly, moderately, or severely abnormal aEEG for prediction of a developmental quotient <85 points, cerebral palsy, or death. FN, false-negative; FP, false-positive; TN, true-negative; TP, true-positive.
aEEG ≤2 wk (separate data for ≤1 wk): Background; normal or abnormal
24 mo: Death, mild impairment (MDI or PDI <85 and ≥70 or GMFCS grade ≥2), or severe impairment (MDI or PDI <70 and GMFCS grade ≥2)
Combined aEEG score: 62.5% of the infants had a normal aEEG score, and out of these 76% had a normal neurologic outcome. Of the infants with an abnormal aEEG score, 24% had a normal neurologic outcome. P < .001.
156 included → 136 at follow-up → 50 had aEEG performed ≤1 wk → 48 included in analysis
Sleep–wake cycling; present or absent
Seizures; present or absent
Combined aEEG score (defined in article); normal or abnormal
Nunes et al 201431
GA: 26–35 wk
EEG days 2–14 (separate data for ≤1 wk): Background abnormalities, dysmaturity pattern, positive sharp waves, electrographic seizures; cutoff between present or absent for all variables
12 mo: Developmental delay,b cerebral palsy,a or epilepsy
Background: RR 1.84 (95% CI 1.18–2.86) for developmental delay, P = .010.
47 included preterm infants (49 term controls) → 7 preterm infants had EEG performed ≤1 wk
Schumacher et al 201332
GA: 24–31 wk
EEG ≤3 d: Total absolute band power; cutoff at 1 SD below average median value
2 y: MDI, PDI, or TMQ <85
Day 1: δ-PP ranged from 0.60 to 0.67, δ-NP from 0.60 to 0.94, θ-PP from 0.29 to 0.57, θ-NP from 0.57 to 0.87, α-PP from 0.40 to 0.71, α-NP from 0.64 to 0.88, β-PP from 0.33 to 0.67, and β-NP from 0.60 to 0.84.
48 included → 41 at follow-up → 21 included in analysis
Hayashi-Kurahashi et al 20127
GA: 22–33 wk
EEG days 1–6: Acute and chronic stage abnormalities; cutoff between none and mild, and mild and moderate
12–18 mo: Developmental quotientc <70 or cerebral palsya
aEEG <24 h: Background; no cutoff, all had discontinuous normal voltage
12 mo: Developmental quotiente <70 or observed neurologic abnormalities
All 12 infants had discontinuous normal voltage on aEEG. Cyclicity was present in 8 infants who had favorable outcomes. One infant showed no cyclicity and had a favorable outcome, and 3 infants with absent cyclicity had abnormal outcomes.
108 recruited → 81 enrolled → 12 included
Cyclicity; present or absent
Maruyama et al 200226
GA: 27–32 wk
EEG ≤1 wk: Acute stage abnormalities; cutoff between normality and 5 grades of abnormality
Normal EEGs were present in all groups (1, normal outcome; 2, minor sequelae; 3, major sequelae; 4, dead) but were more common in groups 1 and 2. In group 1, 61% of the infants had normal EEGs. Moderately abnormal records were present in all groups and appeared to be of no value in predicting outcome. Major EEG abnormalities were present only in survivors with abnormal outcomes.
81 included → 33 had aEEG performed ≤1 wk
The results reported in the Main Findings column are in exact accordance with the reported results in the studies and are not based on additional information received from authors or calculations performed for the purpose of data synthesis. α, α activity; β, β activity; δ, δ activity; θ, θ activity; aEEG, amplitude-integrated EEG; ASA, acute stage abnormalities; GA, gestational age; GMFCS, gross motor function classification system evaluated by neurologic examination; MDI, mental developmental index evaluated by BSID-II; NPV, negative predictive value; PDI, psychomotor developmental index evaluated by BSID-II; PPV, positive predictive value; RR, relative risk; TMQ, total motor quotient evaluated by Peabody Developmental Motor Scales–2.