Table 2

Ascertainment problems and incidence of disability at 6 years (1983 population based cohort of babies born before 32 weeks of gestation)

Follow up		Babies surviving to discharge n=		Intelligence quotient less than 75^2-150 n=		Severe sensorimotor disability n=	Severe sensorimotor or cognitive disability
Follow up		Babies surviving to discharge n=		Intelligence quotient less than 75^2-150 n=		Severe sensorimotor disability n=	n=	%	(95% CI)
Child reviewed without difficulty at 2 and 6 years	203	10	12	17	8.4	5.0 to 13.1
Child only traced at 2 with difficulty (family mobility, etc)	14	0	3	3	21.4	4.7 to 50.8
Assessment at 2 only arranged with difficulty after the child was traced^2-152	12	3	5	5	41.7	15.2 to 72.3
Died after discharge from hospital but before the age of six	7			2^2-151	28.6	3.7 to 71.0
Total	236			27	11.4	7.4 to 15.5

↵2-150 More than 3 standard deviations below average for all the children without severe sensorimotor disability at 6 years.
↵2-151 As in table 1.
↵2-152 Family mobility also added to the difficulty of maintaining contact with two of these 12 families in the first 2 years.