The role of blood transfusions and iron intake on retinopathy of prematurity

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Abstract

Background: The role of blood transfusions and iron intake in the pathogenesis or retinopathy of prematurity (ROP) is controversial. Aim: To evaluate the influence of packed red cell (PRC) transfusions and iron intake on ROP incidence. Study design: Prospective observational study. Subjects: Forty-five preterm infants with birthweight <1250 g were studied. After ophthalmological study, they were divided into group A (n=24) that included newborns without ROP, and group B (n=21) that included newborns with ROP. Results: Logistic regression analysis demonstrated that gestational age (OR 0.61; 95% C.I. 0.41–0.90), transfusion volume during the first week (OR 1.16; 95% C.I. 1.03–1.3) and during the first 2 months of life (OR 2.93; 95% C.I. 1.52–5.62), and iron intake during the first week of life (OR 1.15; C.I. 1.01–1.32) and during the first 2 months of life (OR 2.93; 95% C.I. 1.52–5.62) were associated with the development of ROP. Conclusion: Our study showed that gestational age, blood transfusion volume and iron load by transfusions are associated with the risk of occurrence of ROP in infants with a birthweight of less than 1250 g.

Introduction

Retinopathy of prematurity (ROP) is a vasoproliferative retinal disorder, which represents the main cause of visual impairment and blindness in preterm infants [1]. A recent Italian multicenter study demonstrated that among infants weighing less than 1250 g, 24% were affected by mild forms (grades 1 and 2) of ROP, and 12% by severe forms (grades 3 and 3+) of ROP [2]. Mild forms generally regress with little or no loss of visual function; however, severe forms can lead to retinal scarring and visual loss in the neonatal period.

The pathogenesis of ROP is not fully known, despite a number of perinatal factors, such as prematurity, low birthweight, respiratory distress syndrome, and prolonged oxygen treatment have been recognized as contributory to the development of this retinal disorder [2]. In recent years, the role of blood transfusions and iron intake as risk factors for ROP has been strongly emphasized [3], [4], but the iron intake by transfusions is not generally taken into account when oral iron supplementation is planned in preterm infants. Otherwise, Brooks et al. [5] recently reported that the limitation of blood transfusion does not affect ROP incidence.

The null hypothesis to be tested was that neither blood transfusion nor iron intake increased the risk of ROP in preterm infants. To assess this possibility, we planned a prospective observational study in which the volume of transfused blood and the amount of iron intake was related to the development of ROP in newborn infants with a birthweight of less than 1250 g.

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Methods

Infants who were born between January 1996 and December 1997 and whose birthweight was less than 1250 g were eligible for the study. Exclusion criteria were death within 3 weeks of age, the presence of major congenital malformations, and the absence of parental consent.

For each patient, data regarding birthweight, gestational age, Apgar score, antenatal steroid treatment, erythropoietin (EPO) treatment, age at beginning of iron supplementation, and amount of blood transfusion [volume of packed

Results

After parental consent, 52 infants were enrolled in the study; two had to be excluded due to their death (n=2), and five due to the lack of data. All of remaining 45 infants were subjected to ROP screening. They were divided into group A (n=24) that included newborns without ROP, and group B (n=21) that included newborns with ROP. The highest stage in either eye was stage 1 in 13 infants and stage 2 in eight infants. None of the infants were affected by more severe stages of ROP or underwent

Discussion

The overall incidence of ROP in our infants was 47% (50% in infants with birthweight <1000 g), and all cases were ROP 1–2. The Italian ROP Study Group reported a similar incidence but about half of the cases were ROP 3–3+ [2]. It is difficult to explain the mild severity of ROP in our patients, but it is possible that the moderate frequency of RDS (53%) and the relatively short mean duration of mechanical ventilation (6.0±9.5 days) play a role.

In agreement with previous studies [2], [3], [4],

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