Global developmental delay – globally helpful?

Identification of children with delay in acquisition of developmental milestones is a frequent reason for seeking a paediatric opinion. Around 17% of children referred to a community paediatric clinic, will be because of a developmental concern1 and is acknowledged as affecting 1–3% of children. 2 The role of the paediatrician is to seek to establish the aetiology and to help the child and family. Global developmental delay (GDD) is a term not used in the main index of either the International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10)3 or the National Institute of Health CRISP thesaurus (now replaced by the RePORT Expenditures and Results query tool).4 In the former there is reference to specific developmental disorders, mixed or pervasive, and in the latter the term developmental disabilities is used. The term GDD, however, frequently appears in case notes, discharge letters, and journals. It is widely accepted that this term means significant delay in two or more areas of developmental performance: defined as gross/fine motor, speech/language, cognition, social/personal, and activities of daily living. Significant delay is defined as occurring when performance is two standard deviations below the mean on age appropriate, standardized norm reference tests. On developmental examination, however, we tend to separate gross motor and fine motor developmental domains since delay in one of these does not necessarily mean difficulties in the other (e.g. some neuromuscular disease). In addition, using this definition, children with autism would fulfil the criteria for GDD – but we don’t use this term when we see the triad of impairments associated with autism. I believe, therefore, that in practice we use the term GDD when the child has a motor delay and delays in at least two other areas of developmental performance. The majority of children with late acquisition of several developmental milestones will experience learning disability. As Newton and Wraith5 said, children with learning disability present in various ways and times, some in the newborn period, others in infancy and a few after school entry. It is, important however, that we convey our concerns to the parents in a realistic fashion at time of recognition, neither being too optimistic or pessimistic, but clarifying that delay in acquisition of developmental milestones usually means that the individual will have continuing difficulties with learning later in life.5,6 Do parents who are told their child had GDD appreciate what this means, or do they assume that development is slow but will get to its destination eventually? GDD is a term that parents may find unclear; it certainly is not a diagnosis and should not be used as a diagnostic term. A recent handbook of neurological investigations in children7 classifies the presenting neurological problem as the key to the investigative pathway and late attainment of all milestones is termed learning disability. What, therefore, would I recommend? Firstly, clinicians must continue to take a thorough history, examine the child, use standardized developmental assessments, seek therapists and teachers’ opinions, and describe the problem (e.g. late walking, late talking, etc.). Second, the cause of the delay must be investigated, bearing in mind that even mild delay may have a diagnostic cause.1 The vast majority of children with late development will go onto have learning disabilities of varying degree. There is a paucity of long-term data looking at outcomes of children with slow development under 5 years, but what is available suggests that early recognition of developmental delay appears to predict long-term learning problems. Better outcomes are found in children with more positive family support but further studies are needed.6 Clearly there is no consensus. It may be more helpful to use the ICD terms specific, mixed, or pervasive developmental disabilities, describing the developmental domains which are affected (e.g. walking, communication, etc.). Precision is preferable.