Aetiological investigations in early developmental impairment: are they worth it?

OBJECTIVE: To study the frequency a diagnosis is made in children with early developmental impairment (EDI), and the contribution made to diagnosis by specific investigations. DESIGN: Retrospective case note review. SETTING: Community, neurodisability and neurology department at a UK tertiary centre. PARTICIPANTS: Children referred to determine the aetiology of EDI where a cause was not evident on history and examination. Participants were divided into two groups: EDI and no additional features (EDI-) and EDI with additional features (EDI+). MAIN OUTCOME MEASURES: The frequency a cause was found for the child's EDI and which tests contributed to a diagnosis. RESULTS: 699 participants, 68.8% boys, median age at investigation 2 years 8 months (range 3 months to 11 years 5 months). 61 (8.7%) of participants had no investigations, and children with EDI- were less likely to be investigated (χ2=12.5, p<0.05). A diagnosis was made in 166 children (23.7%) and was more frequent in EDI+ (EDI- 9.9%, EDI+ 27.3%, χ2=19.0; p<0.05). Full blood count, zinc protoporphyrin, renal or liver function, bone profile, biotinidase, creatine kinase or lead level revealed no diagnoses. The following investigations found causes for EDI: MRI (23.1%), microarray (11.5%), Fragile X (0.9%), plasma amino acids (1.2%), urine organic acids (0.9%) and thyroid function tests (0.5%). CONCLUSIONS: The majority of 'screening' investigations for EDI do not contribute to a diagnosis, highlighting an area of cost saving for the NHS and reduced burden for patients and families. We propose a streamlined guideline for the investigation of EDI based on our data.