Cerebral palsy, low birthweight and socio-economic deprivation: inequalities in a major cause of childhood disability

There is currently little and conflicting evidence concerning the existence of socioeconomic inequalities in cerebral palsy prevalence, or the extent to which this is influenced by socio-economic inequalities in low birthweig ht, a strong risk factor for cerebral palsy. The study is based on 753 chil dren registered with cerebral palsy, resident in the former Oxford Regional Health Authority area and born in the years 1984-90. Two population defini tions were used: 1. Children with cerebral palsy resident at birth in the a rea, with resident births as denominator, 2. Children with cerebral palsy r esident at age 5 in the area, with children of ages 1-7 resident in the are a in the 1991 census as denominator. Children with cerebral palsy and all b irths/children were classified according to the Carstairs area deprivation index (grouped into quintiles) of their ward of residence. The prevalence a mong residents at birth varied from 2.08 per 1000 births in the most afflue nt quintile to 3.33 in the most deprived quintile (trend P < 0.001). Althou gh there was a tendency for children to move to more affluent areas during early childhood, the socio-economic gradient was similar at age 5. A greate r proportion of births in the more deprived quintiles were of low or very l ow birthweight, the proportion rising from 5.6% in the most affluent quinti le to 8.2% in the most deprived. Within the normal birthweight category the re was a trend for higher prevalence of cerebral palsy in more deprived qui ntiles, from 1.29 per 1000 in the most affluent quintile to 2.42 in the mos t deprived quintile (trend P < 0.001). Within the low birthweight and very low birthweight groups, separately or combined, there was no evidence of an y relationship between cerebral palsy prevalence and deprivation. We estima te that up to 17% of cerebral palsy cases might be 'preventable' in terms o f the reduction to be expected if the whole population had the rate of cere bral palsy of the most affluent quintile. Although the strong socio-economi c gradient for cerebral palsy was restricted to the normal birthweight cate gory, we estimate that two-thirds of the excess cases in the population ass ociated with greater socio-economic deprivation were normal birthweight cas es, and one-third were low birthweight cases owing to the greater prevalenc e of low birthweight in more deprived populations. The pattern of socio-eco nomic inequalities should be further explored in other regions, and should be taken into account in aetiological research, and in the effective delive ry and evaluation of services.