TO IDENTIFY CAUSES AND CLINICAL MARKERS FOR INCREASING DIAGNOSTIC YIELD FOR CHILDREN WITH GLOBAL DEVELOPMENTAL DELAY (GDD)

Objectives: 1. To study the causes of Global Developmental Delay (GDD). 2. To identify clinical markers useful to improve the diagnostic yield of children with GDD during the initial clinical assessment.

Methods: The Duchess of Kent Child Assessment Centre serves for children aged <15 years of 198,000 (2004). We performed a retrospective consecutive case review of all children with GDD actively seen in 2004. GDD is defined as significant delay (<2 SD) in 2 or more developmental aspects according to the Griffiths Mental Developmental Scale. We selected 9 clinical items that could be elicited during the first clinical assessment (sex, severity of delay, parental consanguinity, family history, behavioral problem, head size, facial dysmorphism, malformations/anomalies and neurological deficits) to see which factor can have a higher chance of detecting an underlying cause for GDD.

Results: 577 children (67% male) were analyzed. The prevalence was 3 per 1,000. These were categorized as mild GDD (63%), moderate (33%) and severe (4%). No causes could be identified in 46%; prenatal (30%), perinatal (20%) and postnatal (4%). Genetic causes accounted for 23% [chromosomal disorders (64%), contiguous gene syndromes/single gene disorders (29%) and syndromes presumed to be genetic (7%). For severity of GDD, a threshold effect was found between mild/moderate GDD [O.R.=2.66, 95% C.I.=1.85–3.83]. Factors that improved the etiological yield of GDD included: 1) female [O.R.=2.045, 95% C.I.=1.43–2.92], 2) absence of behavioral problems [O.R.=6.66, 95% C.I.=4.5–10], 3) microcephaly [O.R.=3.5, 95% C.I.=2.4–5.5], 4) facial dysmorphism [O.R.=4.1, 95% C.I.=2.8–5.9], 5) malformation [O.R.=2.9, 95% C.I.=2.1–4.2], and 6) neurological deficits [O.R.=9, 95% C.I.=6.3–12.8]. A dose-response relationship was found for facial dysmorphism and malformation and the odds ratio increased with increasing number of anomalies. The presence of congenital cardiovascular, pulmonary, gastrointestinal or skeletal anomalies is more likely to be associated with detecting an underlying cause for GDD (p<0.00).

Conclusion: Most checklists for diagnostic workup for GDD aimed at a “selective” diagnostic approach based on disease or syndrome. These 6 clinical markers might be useful during the initial assessment of any children with GDD to predict a higher chance of detecting an underlying organic cause.