Short Stature: Comparison of WHO and National Growth Standards/References for Height.

The use of appropriate growth standards/references is of significant clinical importance in assessing the height of children with short stature as it may determine eligibility for appropriate therapy. The aim of this study was to determine the impact of using World Health Organization (WHO) instead of national growth standards/references on height assessment in short children. Data were collected from routine clinical practice (1998-2014) from nine European countries that have available national growth references and were enrolled in NordiNet® International Outcome Study (IOS) (NCT00960128), a large-scale, non-interventional, multinational study. The patient cohort consisted of 5996 short pediatric patients diagnosed with growth hormone deficiency (GHD), Turner syndrome (TS) or born small for gestational age (SGA). The proportions of children with baseline height standard deviation score (SDS) below clinical cut-off values (-2 SDS for GHD and TS; -2.5 SDS for SGA) based on national growth references and WHO growth standards/references were compared for children aged <5 years and children aged ≥5 years. In seven of the countries evaluated, significantly fewer children aged ≥5 years with GHD (22%; P<0.0001), TS (21%; P<0.0001) or born SGA (32%; P<0.0001) had height below clinical cut-off values using WHO growth references vs. national references. Likewise, among children aged <5 years in the pooled analysis of the same seven countries, a significantly lower proportion of children with GHD (8%; P<0.0001), TS (12%; P = 0.0003) or born SGA (12%; P<0.0001) had height below clinical cut-off values using WHO growth standards vs. national references. In conclusion, in NordiNet® IOS the number of patients misclassified using WHO growth standards/references was significantly higher than with national references. This study highlights that, although no growth reference has 100% sensitivity for identifying growth disorders, the most recent national or regional growth charts may offer the most appropriate tool for monitoring childhood growth in Europe.