Table 1

Details of studies meeting the eligibility criteria

StudyN*GAEvidence of asphyxiaNeurological examInterventionDeviceAge at follow upDefinition of adverse outcome
Jacobs et al 12 40>35A/S <5 or resuscitation at 10 min; Cord pH <7.0; BD >12.Modified Sarnat staging.Whole body cooling (33.0°C–34.0°C) for 72 hours.Ice packs.24 months.Mortality or major sensorineural disability (Bayley II Psychomotor or mental development index <2 SD, cerebral palsy, blindness or deafness) at 2 years of age.
Zhou et al 13 39≥37A/S <6 or need for resuscitation at 5 min; Cord pH <7.0 or BD >16.Modified Sarnat staging.Selective head cooling (rectal temperature 34.5°C–35.0°C) for 72 hours.Cooling cap.18 months.Gesell Child Development Age Scale (Gross Motor Function Classification System level 3–5 or DQ <70).
Thayyil et al 5 19≥36A/S <6 or need for resuscitation at 5 min.Thompson encephalopathy score.Whole body cooling (33.0°C–34.0°C) for 72 hours.Phase change material.42 months.Cerebral palsy, visual or hearing impairment, composite motor score <82 or composite cognitive score <85 on Bayley III.
Battin et al 14 11>37A/S <6 at 5 min; Cord pH <7.Clinical encephalopathy (lethargy/stupor, hypotonia, abnormal reflexes including absent/weak suck).Selective head cooling either: minimally cooled (36.5°C–36.0°C) or mildly cooled (35.9°C–35.5°C) for 72 hours.Cooling cap.18 months.Death, cerebral palsy, Bayley scores >2 SDs from the norm, blindness or hearing impairment requiring amplification, at 2 years of age.
Gluckman et al 6 8≥36A/S <6 or resuscitation at 10 min; pH <7 or BD >16; abnormal aEEG.Modified Sarnat staging.Selective head cooling (34.5±0.5°C) for 72 hours.Cooling cap.18 months.Severe neurodevelopmental disability was defined as (1) gross motor function classification levels 3–5 (non-ambulatory, sits with support applied to lower back or limited or no self-mobility), (2) Bayley Mental Developmental Index of 70 or (3) bilateral cortical visual impairment; at 18 months of age.
Lin et al 1514≥37A/S <6 at 5 min; pH <7 or BD >15.Decreased muscle tone, lethargy, coma or seizures.Selective head cooling with rectal temperature 34.5°C–35.0°C for 72 hours.Cooling cap.10 days.Neonatal Behavioural Neurological Assessment score at 7–10 days of life, CT scan grading at 5–7 postnatal days. No long-term follow-up available.
Eicher et al 162≥36Cord gas pH <7.0 or BD >13, initial infant gas pH <7.1, Apgar score 5 at 10 min or continued resuscitation after 5 min.Any two of: posturing, seizures, autonomic dysfunction or increased/decreased abnormalities of tone, reflexes or state of consciousness.Whole body cooling (33.0°C–34.0°C) for 48 hours.Blanketrol.12 months.Severely abnormal was defined as >2 SDs from mean, moderately abnormal as >1 and ≤2 SD on neurodevelopmental tests of motor function (Bayley Psychomotor Development Index, Vineland gross motor) and cognitive function (Bayley II).
  • *Number of babies with mild encephalopathy.

  • †Not included in the meta-analysis as the authors did not provide the data on babies with mild encephalopathy.

  • ‡Two babies with mild encephalopathy recruited: one withdrew from the study and other lost to follow-up (data provided by the corresponding author). Hence, not included in the meta-analysis.

  • aEEG, amplitude integrated electroencephalography; A/S, Apgar score; BD, base deficit; DQ, developmental quotient; GA: gestational age.