UKCP Collaboration: Analysis of survival and regional variations in CP rates
The UKCP collaboration was established to create an anonymised pooled dataset of cases of cerebral palsy from regional registers of cerebral palsy active in the UK from the 1980s onwards (or before). The pooled dataset was originally created to investigate the survival of children and adults with cerebral palsy and is held at the NPEU. The dataset has been maintained and updated since the original survival analysis (published in 2005) and subsequent work has been conducted by the collaboration. The data have been linked to small area statistics in a project to investigate the relationship between cerebral palsy and social deprivation.
An analysis of intrauterine growth and survival was carried out with the background that deviations in birth weight from optimum are known to increase both the risk of developing cerebral palsy and the risk of developing cerebral palsy of the more severe type. The aim was to investigate influences on survival of such deviations from average birth weight for gestational age since these are not known. Information about a total of 3,946 children with cerebral palsy born between 1980 and 1996 were included. Infants with a birth weight lighter than average of gestational age had an increased likelihood of developing a more severe form of cerebral palsy. Surprisingly, among the infants who were very severely impaired, those born much lighter than average of gestational had the longest life expectancy and those born much heavier than average for gestational age had the shortest life expectancy. A paper reporting these findings has been published in the Fetal and Neonatal Edition of Archives of Diseases in Childhood.
The UKCP pooled dataset was also used to investigate the association between severity of impairment and gestational in unilateral and bilateral spastic cerebral palsy, and to determine whether the influence of gestational age is independent of deviations from optimal birth weight. Information about a total of 4,772 children with spastic cerebral palsy born between 1960 and 1997 were included. The severity of impairment increased with increasing gestational age at birth in bilateral spastic cerebral palsy. Whereas, for unilateral spastic cerebral palsy, severity did not vary with gestational age. This suggests differing aetiologies of cerebral palsy in term and preterm infants and supports the theory that the developing brain is better able to compensate after a cerebral insult. These findings have been reported in the Journal of Paediatrics.
A further analysis of the pooled UKCP data was carried out to identify the patterns of severity of motor impairment in relation to the presence of additional impairments and to birthweight. A second aim was to investigate trends over time in the prevalence of cerebral plasy by birthweight and by severity of motor impairment. The cerebral palsy rate amongst children with a birthweight of <2500g was significantly higher at 16 per 1,000 live births than 1.2 per 1,000 for the normal-birthweight children. Despite being at greater risk of developing cerebral palsy, lower-birthweight babies are less likely to develop the most severe forms of motor impairment: of those born weighting 2500g or greater: 23% compared with 15% weighing <1,000g (P<0.001) were in the most severely motor impaired group. Severe motor impairment is also associated with higher level of additional impairments. Cerebral palsy rates for each motor impairment group in the 1990s were similar to those in the late 1970s. Rates of cerebral palsy among infants born below normal birthweight are high but have decreased over time. These findings have been published in a paper in Paediatric and Perinatal Epidemiology.