Head Circumference – are Irish Babies “Getting Ahead” of the WHO Standards?

Background October 2010 - decision by DOHC to adopt the WHO Child Growth Standards Jan 2013 – launched by HSE Anecdotal reports from hospital and community-based HCPs that, on the WHO growth charts, the head circumference of many Irish babies: - above 99.6th centile - crossing two centiles

Cause for Concern? If head circumference > 99.6th centile - nowhere on chart to plot the reading Possibility of missing pathological diagnosis such as hydrocephalus Referring all these babies, if the finding is commonplace: - high referral rate - generation of anxiety - unnecessary investigation

Reason for Using WHO Charts Set the standard for how all children should grow once their needs are met.

Why use the WHO Charts? A healthy breastfed infant is the standard against which all other infants are compared. All infants in the WHO sample were breastfed at least until aged 12 months and predominantly breastfed for at least 4 months. The breastfed infant is the reference or normative model against which alternative feeding methods are measured with regard to growth, healthy development, and all other short-term and long-term outcomes

Aims of this Report The UK experience Methodology and equipment used by WHO Compare this to the methodology in which of HCPs in Ireland are trained Comparison of the UK-WHO chart against the “old” UK Four in One chart

The UK Experience UK-WHO chart launched in 2009. Impact on head circumference explored by Wright, Inskip et all (2011) Studied 22,000 head circumference measurements by age and sex. UK-WHO charts identified 6-16% of infants with large head circumferences compared with only 1-4% UK1990 chart

How were the WHO Growth Standards Decided?

WHO Multicentre Growth Reference Study Rigorous protocols, standardisation sessions. Careful selection and training of anthropometrists. Children from: Brazil, Ghana, India, Oman, Norway, United States.

Equipment and Methodology Used by WHO Researchers A self-retracting flat metal tape. Remove hairpins or headbands, child held on mother’s lap. Leading observer stood at LHS of child, passed the tape around the head and anchored it just above the eyebrows and over the protuberance at the back of the skull. Assisting observer helped with tape positioning. Once positioned tape was pulled tight to compress hair and skin

Does the Equipment used in Ireland Differ? Instructions on the growth chart state to use a narrow paper or plastic tape. HSE training programme states: “Use a narrow, non-stretchable plastic or disposable paper tape” The equipment used by WHO Researchers was different to that used in Ireland.

Does the use of different equipment matter? Potentially, yes One study looking at different Lass-o tapes found an inter-observer variability of over 1 cm in 9 % of measurements

Does the methodology used in Ireland differ from that used by WHO Researchers?

Methodology used by HCPs in Ireland HSE Training Programme for Public Health Nurses and Doctors: “Measurements should be taken at the maximum occipito-frontalis circumference where the head circumference is the widest.” HSE Land video demonstration – “measure from bony protuberance at back of head to a point midway between the hairline and the eyebrows” Instructions on the growth chart “measure where the head circumference is greatest”. Reminder of the WHO Methodology: Leading observer passed the tape around the head and anchored it just above the eyebrows and over the protuberance at the back of the skull.

In summary, the WHO researchers used... Different equipment Different methodology

Comparing the Growth Charts

How the Charts were Compared For the ages of 3, 6, 9 and 18 months the cm value of a 2nd, 50th and 99.6th centile reading was noted. 2nd, 50th and 99.6th centile readings from the UK-WHO growth chart were replotted on the UK1990 chart and vice versa.

Centimetre value of Centile Readings For each head circumference centile reading the measurement on the UK1990 chart was bigger than the measurement on the UK-WHO centile chart Difference was in the order of 1 cm More noticeable in older babies 50th Centile readings on both charts compared: Age (mths) UK 1990 (cm) UK-WHO (cm) 3 41.5 40.75 6 44.5 43.5 9 46.5 45 18 49.25 47.25

Replotting the centile readings from one chart onto the other Significant differences noted In general a reading on the UK(1990) chart plotted at least one centile higher on the UK-WHO chart. Likewise, readings from the UK-WHO chart plotted at least one centile lower on the UK-1990 chart. Again more marked for older babies. For 18 month old babies: Centile on “old” UK (1990) Chart Centile on UK-WHO Chart 2nd >25th 50th >91st 99.6th Off the chart!

For Example.... UK (1990) Chart UK-WHO Chart 50th Centile 75h Centile

A note on timing... The Irish “Training Programme for Public Health Nurses and Doctors” mention head circumference measurement at every visit as “non-mandatory” growth assessment. UK DoH Guidelines state head circumference should be measured “around birth, at the 6-8 week check, and any time after that if there are any worries about the child’s head growth or development”

Summary WHO researchers who compiled the standards used different equipment and methodology to our HCPs There is a difference between the UK(1990) charts and the UK-WHO charts for head circumference, of at least 1 centile. Use of the WHO growth charts is in line with international best practice. ?Timing of measurements needs to be addressed

Next steps Compilation of a report Presentation of findings to child health steering group Liaison with paediatric neurosurgeons

Recommendations All healthcare professionals involved in the growth monitoring of children should be using the UK-WHO (Ireland) growth charts for plotting these measurements. All staff who monitor the growth of children as part of their work should ensure that their training is up to date in this area. Head circumference measurements should be performed less frequently in Ireland, at a point close to the child’s birth, at the 6 week check and the 3 month check. Thereafter, this measurement should only be performed if there are other concerns in relation to the child’s development. The HSE Growth Monitoring resources on the HSE website and HSELanD should be reviewed and updated as necessary. A communication plan should be drawn up to give renewed focus on the area of growth monitoring and the resources that are available for staff.

If Irish people have big heads we are in good company...