Intellectual disability in cerebral palsy: a population-based retrospective study.

Aim: A population-based observational study design was used to describe the epidemiology of intellectual disability in cerebral palsy (CP) in terms of clinical and neuroimaging associations, and to report the impact of intellectual disability on utilization of health services and length of survival.

Method: Population CP registry data were used to retrospectively assess the frequency of intellectual disability and strength of associations between intellectual disability and mobility, epilepsy, vision, hearing, communication, and neuroimaging patterns (n=1141). Data linkage was undertaken to assess usage of hospital inpatient and emergency department services. Survival analysis was performed in a 30-year birth cohort (n=3248).

Results: Intellectual disability, present in 45% of the cohort, was associated with non-ambulation (47% vs 8%), later walking (mean 2y 7mo vs 1y 9mo), hypotonic (8% vs 1%) or dyskinetic (9% vs 5%) CP, a quadriplegic pattern of motor impairment (42% vs 5%), epilepsy (52% vs 12%), more emergency and multi-day hospital admissions, and reduced 35-year survival (96% vs 71%). Grey matter injuries (13% vs 6%), malformations (18% vs 6%), and miscellaneous neuroimaging patterns (12% vs 4%) were more common in people with intellectual disability.

Interpretation: Intellectual disability adds substantially to the overall medical complexity in CP and may increase health and mortality disparities.

What This Study Adds: Cerebral maldevelopments and grey matter injuries are associated with higher intellectual disability rates. Health care is more 'crisis-driven' and 'reactive' in children with co-occurring intellectual disability. Length of survival is reduced in individuals with CP and co-occurring intellectual disability.