Retinopathy of prematurity: recent advances in our understanding

Outcome following patent ductus arteriosus ligation in premature infants: a retrospective cohort analysis

Background

The patent ductus arteriosus (PDA) is an important problem in premature infants. Surgical PDA ligation is usually only be considered when medical treatment has either failed or was contraindicated. The aims of our study were to determine the mortality and morbidity following patent ductus arteriosus ligation in premature infants, and whether prostaglandin synthetase inhibitor (PSI) use prior to ligation affects outcome.

Methods

A retrospective case note review study to determine the outcome of premature infants undergoing patent ductus arteriosus ligation in one tertiary neonatal intensive care unit and two paediatric cardiothoracic centres.

Results

We had follow-up data on 87 infants. Cumulative mortality rates at 7 days, 30 days and at hospital discharge were 2%, 8% and 20% respectively. The incidence of chronic lung disease, intraventricular haemorrhage, necrotising enterocolitis and retinopathy of prematurity were 77%, 39%, 26% and 28% respectively. There was no difference in mortality, incidence of chronic lung disease or duration of oxygen dependence between those who had and those who had not received a PSI prior to surgical ligation. In those who had received 2 or more courses of PSI prior to surgical ligation, there was a trend to increase in the duration of oxygen therapy and chronic lung disease, but no difference in mortality.

Conclusion

This study shows that patent ductus arteriosus ligation is a relatively safe procedure (30 day survival 92%) but there is substantial late mortality and a high incidence of morbidity in the survivors. 2 or more courses of PSI prior to surgical ligation trends to increased oxygen dependence and chronic lung disease. This high risk population requires careful follow-up. A definitive prospective cohort study is lacking.

EphrinA1 inhibits vascular endothelial growth factor-induced intracellular signaling and suppresses retinal neovascularization and blood-retinal barrier breakdown

The Eph receptor/ephrin system is a recently discovered regulator of vascular development during embryogenesis. Activation of EphA2, one of the Eph receptors, reportedly suppresses cell proliferation and adhesion in a wide range of cell types, including vascular endothelial cells. Vascular endothelial growth factor (VEGF) plays a primary role in both pathological angiogenesis and abnormal vascular leakage in diabetic retinopathy. In the study described herein, we demonstrated that EphA2 stimulation by ephrinA1 in cultured bovine retinal endothelial cells inhibits VEGF-induced VEGFR2 receptor phosphorylation and its downstream signaling cascades, including PKC (protein kinase C)-ERK (extracellular signal-regulated kinase) 1/2 and Akt. This inhibition resulted in the reduction of VEGF-induced angiogenic cell activity, including migration, tube formation, and cellular proliferation. These inhibitory effects were further confirmed in animal models. Intraocular injection of ephrinA1 suppressed ischemic retinal neovascularization in a dose-dependent manner in a mouse model. At a dose of 125 ng/eye, the inhibition was 36.0 +/- 14.9% (P < 0.001). EphrinA1 also inhibited VEGF-induced retinal vascular permeability in a rat model by 46.0 +/- 10.0% (P < 0.05). These findings suggest a novel therapeutic potential for EphA2/ephrinA1 in the treatment of neovascularization and vasopermeability abnormalities in diabetic retinopathy.

Outcome of the Treatment of Retinopathy of Prematurity in Qatar

To evaluate the results of the treatment of Retinopathy of Prematurity (ROP) patients in Qatar a retrospective analysis was made of 43 infants treated between January 1999 and December 2002 initially with indirect laser transpupillary photocoagulation. Cryotherapy was used only on those needing re-treatment. A favorable outcome overall was obtained in 40 cases (90%) after ten received re-treatment. The statistical interpretation, complicating factors and outcomes are discussed. It is concluded that the results of threshold ROP treatment in Qatar are encouraging.

Prenatal risk factors for severe retinopathy of prematurity among very preterm infants of the Australian and New Zealand Neonatal Network

OBJECTIVE

To identify prenatal and perinatal risk factors for clinically severe (stage 3 or 4) retinopathy of prematurity (ROP).

METHODS

Data were collected prospectively as part of the ongoing Australian and New Zealand Neonatal Network audit of high-risk infants (birth weight of <1500 g or gestational age [GA] of <32 weeks) admitted to a level III neonatal unit in Australia or New Zealand. Prenatal and perinatal factors to 1 minute of age were examined for the subset of infants with GA of <29 weeks who survived to 36 weeks' postmenstrual age and were examined for ROP (n = 2105). The factors significantly associated with stage 3 or 4 ROP were entered into a multivariate logistic regression model.

RESULTS

Two-hundred three infants (9.6%) had stage 3 or more ROP. Prematurity was the dominant risk factor, with infants with GA of <25 weeks having 20 times greater odds of severe ROP than infants with GA of 28 weeks. Birth weight for GA also had a "dose-response" effect; the more growth-restricted infants had greater risk, with infants below the 3rd percentile of weight for GA having 4 times greater odds of severe ROP than those between the 25th and 75th percentiles. Male gender was also a significant risk factor (odds ratio: 1.73; 95% confidence interval: 1.25-2.40).

CONCLUSIONS

These data, for a large, essentially population-based cohort, suggest that factors related to the degree of immaturity, intrauterine growth restriction, and male gender contribute to severe ROP.

Cost-effectiveness of digital photographic screening for retinopathy of prematurity in the United Kingdom

OBJECTIVES

To compare the cost-effectiveness of alternative methods of screening for retinopathy of prematurity (ROP) in the United Kingdom, including the existing method of indirect ophthalmoscopy by ophthalmologists and digital photographic screening by nurses.

METHODS

A decision tree model was used to compare five screening modalities for the UK population of preterm babies, using a health service perspective. Data were taken from published sources, observation at a neonatal intensive care unit (NICU), and expert judgment.

RESULTS

We estimated that use of standard digital cameras by nurses in NICUs would cost more than current methods (pound 371 compared with pound 321 per baby screened). However, a specialist nurse visiting units with a portable camera would be cheaper (pound 172 per baby). These estimates rely on nurses capturing and interpreting the images, with suitable training and supervision. Alternatively, nurses could capture the images then transmit them to a central unit for interpretation by ophthalmologists, although we estimate that this would be rather more expensive (pound 390 and pound 201, respectively, for NICU and visiting nurses). Sensitivity analysis was used to examine the robustness of estimates.

CONCLUSIONS

It is likely that there is an opportunity to improve the efficiency of the ROP screening program. We estimate that screening by specialist nurses trained in image capture and interpretation using portable digital cameras is a cost-effective alternative to the current program of direct visualization by ophthalmologists. This option would require the development of a suitable portable machine. Direct comparative research is strongly needed to establish the accuracy of the various screening options.

Incidence of retinopathy of prematurity from 1996 to 2000: analysis of a comprehensive New York state patient database

OBJECTIVE

To determine the current incidence of retinopathy of prematurity (ROP) in New York state.

DESIGN

Population-based cohort study.

PARTICIPANTS

Newborn infants (15 691) with initial hospital length of stay >28 days and date of discharge from January 1, 1996, to December 31, 2000. Subjects were identified from the New York Statewide Planning and Research Cooperative System (SPARCS) database, which contains information about every patient hospitalized in New York during this period.

METHODS

Demographic and clinical information about eligible infants was abstracted by searching the SPARCS database. Patients with a discharge diagnosis of ROP or who underwent laser retinal photocoagulation, scleral buckle, or pars plana vitrectomy were identified by searching for appropriate discharge and procedure codes. Incidence of ROP in the study population was determined and analyzed on the basis of birth weight.

MAIN OUTCOME MEASURES

Incidence of any ROP, laser photocoagulation, scleral buckle, and pars plana vitrectomy in study population.

RESULTS

On the basis of SPARCS coding, the overall incidence of any ROP among all newborn infants in New York state during the study period was 0.2% (2284 of 1 167 427), or 1 in 511. The incidence of any ROP in the study population of newborns with initial hospital length of stay >28 days was 20.3% (2152 of 10 596) among infants with birth weight <1500 g and 27.3% (1839 of 6745) among infants with birth weight <1200 g. Among study patients with any ROP, the proportion who underwent laser photocoagulation during initial hospital stay was 9.5% (218 of 2284), and the proportion who underwent scleral buckle or vitrectomy surgery was 0.5% (12 of 2284). Seventeen study newborns with birth weight > or =2000 g had a discharge diagnosis of ROP, although none of these patients required laser or incisional surgery during hospitalization.

CONCLUSIONS

This study involves the largest known cohort of newborns that has been analyzed for ROP. The incidence of ROP in this study is lower than results from previous multicenter clinical trials. However, the diagnosis of ROP in 17 study newborns with birth weight > or =2000 g deserves further investigation and may have implications for ROP screening protocols.

Rétinopathie du prématuré : résultats de l’examen du fond d’œil chez 94 enfants à risque

PURPOSE

The purpose of this study was to evaluate the incidence and severity of retinopathy of prematurity (ROP) in infants of birth weight less than 1.500 g and/or under 32 weeks'gestation.

METHODS

Ninety-four preterm infants were examined following the Royal College of Ophthalmologists guidelines and retinopathy was graded using the International Classification of ROP. Screening limits were 1 500 g birth weight or 32 weeks'gestational age. Fundus examinations for ROP were performed at 5 weeks'chronological age from birth. Pupil dilation was obtained with instillation of 1% tropicamide three times at 15-minute intervals.

RESULTS

The 94 infants examined for ROP had a median gestational age of 292.3 weeks and a median birth weight of 1 110340 g. ROP was diagnosed in 21 of 94 subjects (22.3%) by fundus examination. ROP stage 3 developed in one preterm infant, ROP stage 2 developed in five preterm infants, and ROP stage 1 developed in 15 preterm infants. No premature babies developed stage 4 or stage 5 ROP. The disease regressed spontaneously in all cases and none of the infants required cryo/laser therapy. In the most premature infants, 23-26 weeks'gestation, 57% developed ROP and one developed severe ROP (stage 3). No disease more posterior to peripheral zone 2 was observed. The incidence of ROP was higher in infants exposed to greater than 21% oxygen (24.2%) than in infants who did not receive oxygen (17.8%). Oxygen, blood transfusion, and cardiopathy appear to be associated with an increased incidence of retinopathy of prematurity.

CONCLUSIONS

ROP continues to be a common problem associated with prematurity in France. This study found a similar incidence of prethreshold ROP when compared to recent studies. The data showed that blood transfusion and cardiopathy may play a role in the development of ROP in premature infants.

Retinopathy of prematurity: any difference in risk factors between a high and low risk population?

PURPOSE

To document incidence of and risk factors for development of retinopathy of prematurity (ROP) in a population of low birthweight infants (< 1500 g).

METHODS

The authors registered clinical characteristics (birthweight, gestational age (GA), Clinical Risk Index for Babies (CRIB), Apgar score, respiratory characteristics (intubation, ventilation, respiratory support, supplemental oxygen, oxygenation index), prescription of dopamine, and maximal creatinemia) by retrospective chart review in two consecutive CRIB score-based (< 851 g, 851-1350 g) categories. Chi square and Mann-Whitney U tests were used to compare clinical characteristics in both categories and a stepwise logistic regression was done to document independent risk factors for either stage 3 (< 851 g) or any grade of ROP (851-1350 g).

RESULTS

Incidence of ROP was 65/157 (41%; 76% in < 851 g and 22% in 851-1350 g). Incidence of stage 3 ROP was 25/46 (54%) in the < 851 g and 4/84 (5%) in the 851-1350 g group. Among other risk factors, maximal creatinemia was a risk factor in the 851-1350 g cohort (p < 0.03). In a logistic regression model, only GA (OR 0.42) remained significant in the lowest birthweight category; in the 851-1350 g cohort, GA (OR 0.53) and CRIB score (OR 1.7) were independent risk factors for ROP.

CONCLUSIONS

In relatively more mature infants (851-1350 g), the risk to develop ROP is based on GA and on neonatal severity of disease (CRIB score); in the tiniest infants, GA is the most important risk factor. Microangiopathy might explain the association of maximal creatinemia and the risk of developing ROP.

State of the Science: Achievements and Challenges Across the Spectrum of Care for Preterm Infants

The spectrum of care for preterm infants includes the perinatal and immediate neonatal periods, the initial hospitalization period including neonatal intensive care, transition to discharge, and from discharge through the first year of life. Care issues are sometimes lifelong. Advances and achievements of the past 20 years, particularly during the perinatal period and in neonatal intensive care, have resulted in significant increases in survivability of even the smallest and least mature infants. Challenges remain, particularly in establishing evidence-based standards of nursing practice in areas such as transition to oral feedings, breastfeeding in the intensive-care nursery, and developmentally based care, and in reducing short- and long-term morbidities in children born prematurely. This article illustrates achievements and challenges across the spectrum of care for preterm infants in the 1st year of life.