J. Vyas et al., Severe retinopathy of prematurity and its association with different ratesof survival in infants of less than 1251 g birth weight, ARCH DIS CH, 82(2), 2000, pp. F145-F149
Background-There is controversy over whether improved survival of preterm i
nfants has resulted in a higher incidence of severe (grade 3 or greater) re
tinopathy of prematurity (ROP).
Aim-To compare survival rates and rates of greater than or equal to stage 3
ROP-that is, with a high risk of sequelae-in preterm infants in five Engli
sh cities where, anecdotally, the incidence of ROP is reported to show cons
iderable variation.
Methods-All infants of birth weight < 1500 g and or gestational age < 32 we
eks, born in 1994 in one of the cities or transferred in within 48 hours, w
ere studied. The populations were adjusted for case mix variation using CRI
B (clinical risk index for babies, a disease severity scoring system). The
incidence of severe ROP, the actual death rate, and that adjusted for disea
se severity were determined.
Results-The rate of severe ROP per 1000 births was higher in city 1 than in
all the other cities. This increase in comparison with city 2 and city 4 w
as significant (city 1, 167 (95% confidence interval (CI) 96 to 260); city
2, 24 (6 to 59); city 4, 16 (1 to 84)). A significant difference was not se
en between city 1 and cities 3 (23 (1 to 120)) and 5 (74 (21 to 79)). The r
elative risk of developing severe ROP in city 1 compared with all the other
cities was 5.5 (2.5 to 11.9). The actual death rate per 1000 births in cit
y 1 was significantly lower than that predicted by modelling death against
CRIB score (city 1: actual 270; predicted 385 (95% CI 339 to 431)). In cont
rast, the other cities had actual death rates as predicted, or worse than p
redicted, by CRIB.
Interpretation-A significantly higher incidence of severe ROP was identifie
d in one of the five cities studied. Variation in survival rates among high
risk infants may explain this observation.