Increasing rates of cerebral palsy across the severity spectrum in north-east England 1964-1993

Objectives-To report epidemiological trends in cerebral palsy including ana lyses by severity. Design-Descriptive longitudinal study in north-east England. Every child wi th suspected cerebral palsy was examined by a developmental paediatrician t o confirm the diagnosis. Severity of impact of disability was derived from a parent completed questionnaire already developed and validated for this p urpose. Subjects-All children with cerebral palsy, not associated with any known po stneonatal insult, born 1964-1993 to mothers resident at the time of birth in the study area. Main outcome measures-Cerebral palsy rates by year, birth weight, and sever ity. Severity of 30% and above defines the more reliably ascertained cases; children who died before assessment at around 6 years of age are included in the most severe group (70% and above). Results-584 cases of cerebral palsy were ascertained, yielding a rate that rose fi om 1.68 per 1000 neonatal survivors during 1964-1968 to 2.45 during 1989-1993 (rise = 0.77; 95% confidence interval 0.2-1.3). For the more rel iably ascertained cases there was a twofold increase in rate from 0.98 to 1 .96 (rise = 0.98; 95% confidence interval 0.5-1.4). By birth weight, increa ses in rates were from 29.8 to 74.2 per 1000 neonatal survivors < 1500 g an d from 3.9 to 11.5 for those 1500-2499 g. Newborns < 2500 g now contribute one half of all cases of cerebral palsy and just over half of the most seve re cases, whereas in the first decade of this study they contributed one th ird of all cases and only one sixth of the most severe (chi(2) and chi(2) f or trend p < 0.001). Conclusions-The rate of cerebral palsy has risen in spite of falling perina tal and neonatal mortality rates, a rise that is even more pronounced when the mildest and least reliably ascertained are excluded. The effect of mode rn care seems to be that many babies < 2500 g who would have died in the pe rinatal period now survive with severe cerebral palsy. A global measure of severity should be included in registers of cerebral palsy to determine a m inimum threshold for international comparisons of rates, and to monitor cha nges in the distribution of severity.