UK auxological referral criteria have low sensitivity for pathological short stature

medwireNews: Using both height and deviation from height target during growth monitoring could improve detection of pathological growth disorders in children and avoid unnecessary clinic referrals, suggest UK researchers who found the current criteria to have low sensitivity.

Helen Storr, from Queen Mary, University in London, and co-authors reviewed medical records for 143 children with short stature who were referred to paediatric endocrinology clinics at the Royal London Hospital between 2016 and 2021 by primary (32%), secondary (65%) or tertiary (3%) centres.

The team explains that abnormal linear growth in the UK is defined as a height standard deviation score (HtSDS) of less than –2.7, a height SDS minus target height SDS (Ht-THSDS) greater than 2.0 and a height deflection SDS (HtDefSDS) greater than 1.3. By comparison, the Dutch thresholds for these criteria are less than –2.0, greater than 1.6 and greater than 1.0, respectively.

The majority (72%) of children referred were boys and the average age at the time of referral was 8.7 years, with no significant difference in age or average HtSDS between boys and girls.

Overall, 114 of the children were found to have short stature and 29 children to have normal stature.

Specifically, 51 children had pathological short stature with a mean HtSDS of –2.63 and this was attributed to primary growth failure (n=28), such as small-for-gestational age with no catch-up growth in 21 cases, or secondary growth failure (n=23), most commonly growth hormone deficiency in 17 cases.

A further 15 children had short stature of unknown aetiology with a mean HtSDS of –2.78, 12 of whom were followed up with active surveillance for up to 5.4 years and continued to have abnormal growth during this time.

In addition, 48 children had non-pathological short stature with a mean HtSDS of –2.34, and these children were classified as having familial short stature (n=30) or constitutional delay of growth and puberty (CDGP; n=18).

Children whose short stature was pathological or of unknown aetiology had a significantly lower mean HtSDS and Ht-THSDS than those with nonpathological short stature or normal stature (–2.67 vs –1.97 and –2.07 vs –1.06, respectively).

Overall, the UK HtSDS criteria were 41% sensitive and 83% specific for identifying pathological short stature, with corresponding rates for the Ht-THSDS of 48% and 83% and the HtDefSDS of 33% and 68%.

Meeting any of the three criteria was 80% sensitive for identifying short stature but the specificity was reduced to 52%. However, when either HtSDS and/or Ht-THSDS criteria were met, the sensitivity was 68% and the specificity was 75%.

The Dutch criteria for HtSDS was more sensitive than the UK version at 59% but had slightly lower specificity at 79%. The corresponding values for Ht-THSDS using the Dutch criteria were 74% and 72%, and for HtDefSDS the values were 44% and 63%.

“Adoption of less stringent Dutch cut-offs may enhance detection of true positives but at the cost of increased healthy referrals”, Storr et al comment.

The researchers note that just one child with familial short stature and three of normal stature did not undergo any of the recommended diagnostic investigations for children referred to secondary or tertiary care for short stature, including a full blood count, renal and liver function tests, karyotyping and bone age assessments.

Of the 139 children who underwent investigation, 47% of children with pathological short stature and 73% of children with short stature of unknown aetiology received all recommended investigations, as did 53% of children with familial short stature and 72% of those with CDGP.

Of concern, 41% of children with normal stature also underwent all recommended investigations, prompting the investigators to observe that “[a]lthough the patients with normal stature had fewer investigations, many underwent unnecessary testing.”

Storr and co-authors also highlight that 21% of children had familial short stature that could have been identified by assessment of parental height before referral. “Consideration of the child’s genetic target height can prevent unnecessary referral, investigation and health service resource wastage”, they write.

The team concludes in BMJ Paediatrics Open: “Combining the subject’s height and its deviation from target height is more valuable than any isolated criterion in discriminating between normal variant and pathological short stature.

“This combined approach will lead to improved detection of pathology and reduce inappropriate referrals, enabling more children with genuine short stature to be identified and access rapid baseline investigations earlier to confirm or exclude pathology”, they continue.

By Lynda Williams

medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2022 Springer Healthcare Ltd, part of the Springer Nature Group

BMJ Paed Open 2022; 6: doi: 10.1136/bmjpo-2021-001385
Martin Savage
Programme Director

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