Purpose
To evaluated the impact of small for gestational age (SGA) as a risk factor for retinopathy of prematurity (ROP) requiring treatment.
Methods
In total, 2941 preterm infants born <32 weeks (wk) gestational age (GA) were eligible from five cohorts previously collected for WINROP (Weight IGF-I Neonatal ROP) analysis: Swedish (EXPRESS) (n=426), North American (n=1772), Boston (n=338), Lund (n=52), and Gothenburg (n=353). Data regarding GA, birth weight (BW), gender and ROP treatment were retrieved. Birth weight standard deviation scores (BWSDS) were calculated. SGA was defined as BWSDS less than −2.00 SDS. Risk factors; GA wk at birth, BW (50 g increments), gender, SGA and BWSDS were evaluated by both univariate and multiple logistic regression analysis.
Results
The frequency of SGA amongst infants treated for ROP increased with GA wk; of the infants treated for ROP born at GA 23 wk 4% were SGA whereas 66% of the infants treated for ROP born at GA 27 wk were SGA. In univariate analysis low GA wk at birth (p<0.001), low BW (p<0.001) and male gender (p<0.05) were significant risk factors for ROP requiring treatment, but not BWSDS nor SGA. In subgroup analysis, for infants born <26 wk GA (n=816) low GA (p<0.001) and low BW (p<0.001) were risk factors while for infants born ≥26 wk GA (n=2125) BWSDS and SGA were risk factors (p<0.001) in addition to low GA and low BW. In multiple logistic regression analysis SGA (p<0.001), male gender (p<0.01), and low GA (p<0.001) were independent risk factors for ROP requiring treatment. In subgroup analysis, for infants born <26 wk GA, SGA (OR=1.75, 95% CI 1.14-2.69, p=0.01), male gender (OR=1.53, 95% CI 1.11-2.11, p=0.01), and low GA (OR=0.48, 95% CI 0.39-0.59, p<0.001) were independent risk factors for ROP requiring treatment. For infants born ≥26 wk GA, SGA (OR=3.65, 95% CI 2.19-6.08, p<0.001) and low GA (OR=0.41, 95% CI 0.32-0.51, p<0.001) were risk factors for ROP requiring treatment for ROP.
Conclusions
SGA as a risk factor for sight threatening ROP is dependent on degree of immaturity. In the most immature infants, SGA is a less important risk factor for ROP requiring treatment than GA at birth while for the more mature infants SGA becomes a major risk factor for developing ROP requiring treatment. For instance infants born ≥26 wk GA had an almost 4 fold increased risk of ROP requiring treatment if born SGA.
Keywords: 706 retinopathy of prematurity •
688 retina •
698 retinal development