Developmental outcome at 6.5
years after acidosis in Term
Newborns
SCH medics Journal Club
Thursday 12th July 2012
Faith Harries
Aim
To evaluate whether metabolic acidosis at birth in term
infants who appear healthy is associated with long term
developmental abnormalities
Objectives
• Search for relevant literature to the clinical question
• Select a useful paper to discuss
• Is the paper valid and reliable enough to answer the
question?
• Does clinical practice need to change?
Case presentation
Whilst on call a midwife rings the neonatal team to tell them
that Baby S has had a cord gas which shows a pH 7.01 – is
there anything the neonatal team want to do?
Baby S is a term baby who was delivered by emergency
LSCS for foetal bradycardia. He needed no resuscitation, had
good apgars and is now with his mother on the postnatal
ward. He appears healthy and well.
The clinical question
Population
Children aged 6.5 years
Intervention
Those with a metabolic acidosis
Comparison
Matched controls
Outcome
Long-term developmental abnormalities
Design
Cohort study
In children who were born full term and were apparently healthy
(P), is metabolic acidosis (I) associated with long-term
developmental abnormalities (O).
Literature search
[Metabolic acidosis OR acidosis] AND [developmental
outcome] = 76 search results
Further search using [Metabolic acidosis OR acidosis] AND
developmental outcome OR neurodisability] = 28 results
Resource searched: Medline
Developmental Outcome at 6.5 years After Acidosis
in Term Newborns: A Population-Based Study
Maria Hafström, Siv Ehnberg, Sofia Blad, Håkan Norén, Cecilia
Renman, Karl Gustaf Rosén and Ingemar Kjellmer
Pediatrics 2012;129;e1501
Current practice
• Paired cord gases are not routinely recommended
• Taken when there are concerns about the baby in labour
or immediately after the birth
• Well babies with acidosis on gases are reviewed by
neonatal team
Methods
• Prospective observational study (Gothenburg and
surrounding areas)
• Intrapartum fetal surveillance introduced – continuous
evaluation of the ST segment of the fetal ECG combined
with carditocography (CTG) analysis STAN methodology
• 2 year period (October 2000 – September 2002)
• 14687 term deliveries
• 2 groups identified
• 78 had cord artery metabolic acidosis (group A)
• Metabolic acidosis defined = umbilical artery pH < 7.05 and
base deficit > 12.0 mmol/L
• Control cases identified (group B)
Methods (2)
• Infants placed into four groups according to their treatment
need in the neonatal period
• Children were identified using Swedish national registration
system and school health database system
• Records scrutinised for developmental data, referral actions
or proceedings for specific educational support
• Data extraction, evaluations and categorisation were
performed independently by 2 paediatricians who were
blinded to the conditions at birth
• Difference in the two groups was calculated by using the
Mann-Whitney nonparametric test
• Χ2 distribution test used to analyse the frequency of the
different categories in the different acidotic groups and the
control group
Flowchart for the study population
Neurodevelopmental Categorization
Category
Criteria
Criteria
1
No symptoms or divergence in educational or neurodevelopmental
aspect. No referral activities except for the following diagnoses and
symptoms: health problems concerning asthma, allergy, enuresis,
growth, obesity, visual problems that are fully compensated for with
glasses, or hearing evaluation associated with otitis.
2
Divergence noted for speech, language and behavior but no
referral action taken. Visual problems not fully compensated by
glasses, ie, squint
3
Divergence for speech, language, behavior, and motor problems
where referral action is obtained. Specific educational arrangements
in the school system
4
Specified diagnosis in the area of neurodevelopment
5
Dead
Lost to
follow up
Lost to follow up, including those children who had emigrated
Outcome measures
• Numbers undergoing ordinary healthcare follow-up
• Numbers undergone special development assessment
• Age at assessment
• Mortality
• Lost to follow-up numbers
• Head circumference at 18 months
• Weight, height and BMI at 6.5 years
CRITICAL APPRAISAL SKILLS PROGRAMME
Making sense of evidence about clinical effectiveness
A Are the results of the study valid?
Screening Questions
1. Did the study address a clearly focused issue?
YES
2. Did the authors use an appropriate method to answer their question?
YES
- a prospective cohort study using a control group
Detailed questions
3. Was the cohort recruited in an acceptable way?
YES
4. Was the exposure accurately measured to minimize bias?
partly a
the
NO – categorisation of being healthy in the neonatal period is
subjective judgment, physician chose the level of care needed and
level of follow-up.
5. Was the outcome accurately measured to minimize bias?
though all
diagnosis were
CAN’T TELL – physician made subjective judgement initially
acidotic infants who developed a neurodevelopmental
treated in the SCBU and assigned to this follow-up.
Outcome data was collected retrospectively – though matching of
controls was done prospectively
6 A. Have the authors identified all important confounding factors?
YES – subjective judgment of physician, blinding the paediatricians
to the conditions at birth
B. Have they taken account of the confounding factors in the design and/or
analysis?
YES – all acidotic infants who developed a neurodevelopmental
diagnosis were treated in the SCBU and assigned to this
follow-up;
the same nurse examined all of the notes; matched paired
analysis was omitted because 11 of 78 allocation
groups was not complete
7A Was the follow up of subjects complete enough?
CAN’T TELL – minor neurodevelopmental problems at this age may
not be discovered/reported
B Was the follow up of subjects long enough?
NO – this age group have only been in school for 0.5-1 year,
problems may manifest after more time
B What are the results?
8. What are the results of this study?
All infants in this study who were born with metabolic acidosis who
appeared healthy at birth and who were not treated in the SCBU were
without neurological diagnosis at 6.5 years of age
9. How precise are the results?
Small confidence intervals were used and showed no significance
when comparing the healthy infants to the control group.
10. Do you believe the results?
YES
Will the results help me locally?
11. Can the results be applied to the local population?
YES – we have national guidelines on when cord gases
should be
taken (NICE); children in the UK attend school
from an earlier
age and problems will have usually been
noted/reported by 6.5
years of age
12. Do the results of this study fit with other available evidence?
YES – systematic review and meta-analysis have shown
that a
low arterial cord pH showed strong, consistent and
temporal
associations with clinically important
neonatal outcomes that
are biologically plausible. (BMJ
2010;340:c1471)
Summary and Conclusion
The first prospective cohort study to determine whether
metabolic acidosis (as defined) affects the
developmental outcome in apparently healthy term
newborns.
CLINICAL BOTTOM LINE
Neonates who appear well after perinatal metabolic
acidosis do not have an increased risk of neurological or
behavioural problems at the age of 6.5 years