Developmental outcome at 6.5 years after acidosis in Term Newborns

SCH medics Journal Club Thursday 12 th 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

Intervention Comparison Outcome Design

Children aged 6.5 years

Those with a metabolic acidosis Matched controls Long-term developmental abnormalities 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 Χ 2 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

2 3 1

Neurodevelopmental Categorization Criteria

Criteria

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.

4 5 Lost to follow up Divergence noted for speech, language and behavior but no referral action taken. Visual problems not fully compensated by glasses, ie, squint Divergence for speech, language, behavior, and motor problems where referral action is obtained. Specific educational arrangements in the school system Specified diagnosis in the area of neurodevelopment Dead 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 follow-up; diagnosis were treated in the SCBU and assigned to this 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? should be YES – we have national guidelines on when cord gases taken (NICE); children in the UK attend school from an earlier noted/reported by 6.5 age and problems will have usually been years of age 12. Do the results of this study fit with other available evidence? that a temporal YES – systematic review and meta-analysis have shown neonatal outcomes that 2010;340:c1471) low arterial cord pH showed strong, consistent and associations with clinically important are biologically plausible. (

BMJ

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