Neurodevelopmental outcomes in preterm infants with retinopathy of prematurity

Interdisciplinary collaborative eye examinations to protect preterm infant neurodevelopment: a quality improvement project

Introduction

Infants born <31 weeks gestational age with birth weight ≤ 1,500 grams receive routine eye examinations to screen for Retinopathy of Prematurity (ROP) while in the Neonatal Intensive Care Unit (NICU) to help prevent vision threatening complications; however, preterm infants' sensory systems are underdeveloped, and repeated exposure to painful stimuli is associated with worse developmental outcomes.

Methods

An interdisciplinary NICU team designed a collaborative eye exam model (CEEM) incorporating best practice recommendations for infant pain control during exams. Pain scores and vital signs were recorded before, during, and after exams. Two sets of mixed-effects regression models with a random intercept on infants were established to investigate relationships between the intervention, birth gestational age (BGA), postmenstrual age (PMA), and outcomes associated with painful stimuli. Survey feedback was elicited from NICU stakeholders about the CEEM.

Results

Thirty standard of care (SC) and 35 CEEM exams of 37 infants were included in final analysis. In infants of the same BGA, the number of desaturation events was significantly reduced in the CEEM group (p = 0.003) and became 1.53 times smaller with each additional week of BGA (p = 0.009). Probability of heart rate recovery within 15 min lowered significantly in the CEEM group (p = 0.04). In SC or CEEM or between infants of the same PMA, no differences were observed for bradycardia, heart rate range, chance of heart rate recovery, or pain scores. Increases in tachycardia (p < 0.001) events and desaturations p = 0.006 were discovered in the CEEM group. When considering interaction effects, the CEEM appeared to reduce the number of desaturations to a greater degree for infants at earliest BGAs with attenuation of this effect with greater BGA. Regarding PMA, bradycardia and tachycardia events were reduced for infants across PMAs in the CEEM, but the effect for tachycardia improves with age, while the effect for bradycardia diminishes with age. Stakeholders agreed that the infant's eye exam experience and the staff experience was "very much" improved by the CEEM.

Discussion

Despite variable findings in selected outcome measures, the CEEM was positively viewed by staff. Infants may benefit from the CEEM differently based on BGA and PMA.

Long-term follow-up of the cognitive function in children after intravitreal ranibizumab for retinopathy of prematurity

PURPOSE

To evaluate the long-term cognitive function in children treated with intravitreal ranibizumab (IVR) for retinopathy of prematurity(ROP), and the impact of IVR on the growth and ocular development.

METHODS

In this retrospective study, the premature children aged 4 to 9 years who received monotherapy of IVR (IVR group, n = 25) or monotherapy of laser photocoagulation (LP) (LP group, n = 33) for ROP, and the same age premature children with no ROP (Control group, n = 26) were enrolled from 2020 to 2022 in the pediatric fundus clinic of Shenzhen Eye Hospital. Main outcome measures were full-scale intelligence quotient (FSIQ) and index score using the Chinese version of the Wechsler intelligence scale for children-fourth edition (WISC-IV) and Wechsler preschool and primary scale of intelligence-fourth edition (WPPSI-IV). All children were examined and analyzed for growth and ocular development by recording the height, weight, head circumference, spherical equivalent (SE), best corrected visual acuity (BCVA) and axial length (AL).

RESULTS

There were 17 children in IVR group, 17 in LP group, and 11 in Control group who received the WISC-IV assessment. There were no significant differences in FSIQ, verbal comprehension index, perceptual reasoning index, working memory index, processing speed index, general ability index and cognitive efficiency index among the three groups. There were 8 children in IVR group, 16 in LP group, and 15 in Control group who received the WPPSI-IV assessment. There were no significant differences in FSIQ, verbal comprehension index, visuospatial index, fluid reasoning index, working memory index, non-verbal index, general ability index and cognitive efficiency index among the three groups. There was no significant difference in BCVA among the three groups (P = 0.74), however, there is an increase for AL in IVR group when compared with LP group (22.60 ± 0.58 vs. 22.13 ± 0.84, P = 0.003), and the ROP patients of IVR group have a significant increase in the AL compared to the Control group(22.60 ± 0.58 vs. 22.03 ± 0.71, P < 0.0001).

CONCLUSIONS

Children with a history of IVR have a similar cognitive function outcomes compared to those with a history of LP or were premature without ROP. ROP children with a history of IVR has longer AL than those treated with LP.

Intra-Anterior Chamber Injection of Ranibizumab in Advanced Pediatric Vitreoretinal Diseases

Importance

Anti-vascular endothelial growth factor (VEGF) treatment through intravitreal or subretinal administrations has been proven effective for VEGF-driven pediatric vitreoretinal diseases but are not feasible for advanced cases, such as shallow traction retinal detachments or peripheral circumferential retinal detachments which adhere to the lens. Intra-anterior chamber injection (IAcI) of anti-VEGF may be a viable alternative in such cases but needs evaluation.

Objective

To investigate the effects and safety of IAcI of anti-VEGF to treat VEGF-driven pediatric vitreoretinal diseases.

Design, Setting, and Participants

This was a retrospective observational case series study conducted at Xinhua Hospital, affiliated with Shanghai Jiao Tong University School of Medicine in China. The study included 14 eyes of 13 children diagnosed with vitreoretinal disease exhibiting elevated vascular activity between January and August 2023.

Intervention

IAcI with ranibizumab.

Main Outcomes and Measures

Retinal vascular abnormalities, vitreous hemorrhage resolution, and complications 1 month and 3 months after injection.

Results

Of 13 patients included in this study, 12 were male. The mean age was 4.6 years (range, 1 month to 9 years). Six patients were diagnosed with familial exudative vitreoretinopathy, 4 with morning glory syndrome, 1 with retinopathy of prematurity, and 2 with chronic retinal detachments of unknown causes. At 1-month postoperative follow-up, vascular activity had decreased in 14 of 14 eyes. At 3-month follow-up, vascular activity had resolved in 7 of 14 eyes, persisted in 6 of 14 eyes, and reactivated in 1 of 14 eyes. On final observation, no complications were reported.

Conclusions and Relevance

These findings support the possibility of treatment using IAcI with ranibizumab to decrease retinal vascular abnormalities in familial exudative vitreoretinopathy or retinopathy of prematurity or related conditions, but further studies are needed to understand more precise benefits and risks. This approach might be considered in cases where intravitreal or subretinal injection are not feasible, recognizing the limitations of these findings and that longer-term outcomes still need to be monitored.

Blindness is decreasing among children born preterm during the last four decades in Denmark

PURPOSE

Children born preterm are believed to be at increased risk of visual impairment (VI). The increased survival rate of extremely preterm children may have changed the spectrum of diseases occurring postnatally. The aim of this study was to analyse the prevalence and causes of VI in an ex-preterm Danish population during the last 4 decades.

METHODS

The study was based on the National Register of Blind and Visually Impaired Children (NRVIC). Ex-preterms born at gestational age (GA) <32 weeks and enrolled in NRVIC at any time between 1988 and 2020 were included. The main cause of VI, the severity of VI and systemic comorbidities were analysed for temporal changes.

RESULTS

A total of 335 patients were included. The prevalence of VI decreased from 26/1000 preterm children in the 1980s to 15/1000 in 2000s. Blindness due to preterm birth is almost eliminated affecting 1/1000 today. Sequelae to retinopathy of prematurity (ROP) was the most common cause of VI (51% of cases) in the 1980s but decreased to 34% in 2010s, whereas non-ocular causes of VI increased from 1% to 36%, respectively. More than half of the children (64%) had combined comorbidities and 36% had isolated VI.

CONCLUSION

The improved monitoring in neonatal intensive care units and management of ROP has reduced the prevalence of severe VI due to ROP and almost eliminated blindness over the last decades in Denmark. However, preterm children are still at risk of non-ocular causes of VI and comorbidities following the premature delivery.

A meta-analysis of adverse effects of retinopathy of prematurity on neurodevelopment in preterm infants

BACKGROUND

Retinopathy of prematurity (ROP) increases with the survival of late preterm infants, but its relationship with neurodevelopmental outcomes in preterm infants remains controversial. To investigate the relationship between ROP and its severity and adverse neurodevelopmental outcomes in preterm infants.

METHODS

We conducted a meta-analysis. All relevant literature before November 2022 were retrieved from PubMed, Embase, Cochrane Library Web of Science, CNKI, CBM, Wan fang Data, and VIP Database. According to the inclusion criteria and exclusion criteria, eligible literature were included to conduct clinical trial quality assessment, and the Newcastle-Ottawa scale was used to evaluate the quality of evidence. Meta-analysis was performed using RevMan5.3. Data extraction, quality assessment, and meta-analysis were performed independently by 2 people. Mean difference or standardized mean difference of motor, language and cognitive scores (Bayley III or Bayley II) were used as effect sizes for continuous data analysis, all of which were represented by 95% CI. For heterogeneity (I2 ≥ 50% or P < .10), a random effects model was used, otherwise a fixed effects model was used.

RESULTS

A total of 6 literature were included. The results of the ROP group for motor (comprehensive motor, proportional motor, and fine motor), language and cognitive scores were -5.57 (95%CI, -1.43 to 0.04), -0.95 (95%CI, 1.4-0.50), -1.34 (95% CI, 1.77-0.92), -1.75 (95% CI, 2.26-1.24) and -5.56 (95% CI, 9.56-1.57). Additionally, the results of severe ROP group for motor (comprehensive motor, proportional motor, fine motor), language and cognitive scores were -8.32 (95%CI, -8.91 to 7.74), -1.10 (95%CI, -1.83 to -0.36), -1.08 (95%CI, -1.75 to -0.41), -7.03 (95%CI, -7.71 to 6.35), and -7.96 (95%CI, -8.5 to -7.42).

CONCLUSIONS

The Bayley Scale scores of the ROP group were lower than those of the not ROP group, and the scores of the severe ROP were significantly lower than those of the not severe ROP group. These findings suggest that ROP can indeed delay motor, language and cognitive, especially in severe cases.

Association between severe retinopathy of prematurity (ROP) and poor motor neurodevelopmental outcome

During the final (third) trimester outside of the womb, the retina develops significantly and is vulnerable to problems. Similar to how the cerebral cortex does, the cerebellum also grows quickly during this time and is susceptible to upsetting environmental influences. The only factors that show promise for lowering the incidence and retinopathy of prematurity (ROP) severity among high-risk infants are prematurity prevention, preeclampsia control, and prudent use of oxygen therapy and ventilation. The third trimester is when the cerebral cortex, cerebellum, and retina develop. These areas are vulnerable to environmental influences if their development is interrupted. Throughout childhood and adolescence, neurodevelopmental defects have been linked to impaired cortical development and smaller brain volumes. Reduced cerebellar volumes have been linked to an increased risk of autism spectrum disorder, lower motor performance, impaired executive functioning, and poorer cognitive outcomes. The complete avascular retina, as well as the peripheral retina, should be treated during retinal ablation with laser photocoagulation (using a transpupillary diode, 11 argon, and three FD-YAG) or cryoablation as failing to do so promotes disease progression and results in unfavorable anatomical and refractive outcomes.

Exposure of preterm neonates receiving total parenteral nutrition to phthalates and its impact on neurodevelopment at the age of 2 months

This prospective study assessed the exposure to phthalates of preterm neonates who received total parenteral nutrition (TPN) during their stay in the neonatal intensive care unit (NICU) and the risk of neurodevelopment delays at the age of 2 months. Our study recruited 33 preterm neonates who required TPN upon NICU admission. Urine samples for analyzing phthalate metabolites were obtained at admission and then daily until the last day of receiving TPN. Phthalates in the daily TPN received by the preterm neonates were analyzed. The neurodevelopment of the neonates was assessed using the Ages and Stages Questionnaire Edition 3 (ASQ-3). Diethyl phthalate and butyl benzyl phthalate were found in all TPN samples, while 27% and 83% contained dibutyl phthalate and di-(2-ethylhexyl) phthalate (DEHP), respectively. Yet, the daily dose of each phthalate that our preterm neonates received from TPN was much lower than the recommended tolerable limit. Urinary levels of monobenzyl phthalate and four metabolites of DEHP [i.e., mono-(2-ethylhexyl) phthalate (MEHP), mono-(2-ethyl-5-hydroxyhexyl) phthalate, mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP)] and the sum of four DEHP metabolites (∑₄DEHP) increased significantly in preterm neonates before discharge. However, these levels were not correlated with their phthalate parent compounds in TPN, suggesting other sources of exposure in the NICU. At 2 months, we found that urinary levels of mono-iso-butyl phthalate (MiBP), MECPP, MEHP, and ∑₄DEHP were inversely related to fine motor skills. After adjusting for head circumference, the inverse relationships remained significant, suggesting direct effects from phthalates. Given the extreme vulnerability of our population, it is critical to minimize exposure to phthalates during their NICU stay.

Neurodevelopmental Outcomes for Retinopathy of Prematurity: A Taiwan Premature Infant Follow-up Network Database Study

PURPOSE

To evaluate the neurodevelopmental outcomes in premature infants who received intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections to treat retinopathy of prematurity (ROP).

DESIGN

Retrospective cohort study.

METHODS

This study was conducted using the database from the Taiwan Premature Infant Follow-up Network. Demographic data, systemic risk factors, ROP status, and neurodevelopmental assessment using the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) were collected. Patients were divided into 4 groups: prematurity without ROP, ROP without treatment, ROP with laser treatment, and ROP with intravitreal anti-VEGF treatment. A generalized estimating equation was used for analyzing repeated measurements of Bayley-III at the corrected ages of 6, 12, and 24 months.

RESULTS

A total of 2090 patients with a mean gestational age of 31.2 weeks were included. The Bayley-III composite scores of patients with ROP treated with anti-VEGF were comparable to those of patients with ROP without treatment (cognitive: P = .491; language: P = .201; motor: P = .151) and premature patients without ROP (cognitive: P = .985; language: P = .452; motor: P = .169) after adjusting for confounders. Patients with ROP treated with laser photocoagulation exhibited poorer cognitive composite scores than did those without treatment (P < .001), premature patients without ROP (P < .001), and those treated with anti-VEGF (P < .001), but they had similar language and motor composite scores.

CONCLUSIONS

Intravitreal anti-VEGF treatment for ROP was not associated with adverse neurodevelopment in premature infants. Further studies are needed to determine whether general anesthesia or sedation used in laser treatment for ROP has significant impacts on neurodevelopmental outcomes.

Retinopathy of prematurity: A review of pathophysiology and signaling pathways

Retinopathy of prematurity (ROP) is a vasoproliferative disorder of the retina and a leading cause of visual impairment and childhood blindness worldwide. The disease is characterized by an early stage of retinal microvascular degeneration, followed by neovascularization that can lead to subsequent retinal detachment and permanent visual loss. Several factors play a key role during the different pathological stages of the disease. Oxidative and nitrosative stress and inflammatory processes are important contributors to the early stage of ROP. Nitric oxide synthase and arginase play important roles in ischemia/reperfusion-induced neurovascular degeneration. Destructive neovascularization is driven by mediators of the hypoxia-inducible factor pathway, such as vascular endothelial growth factor and metabolic factors (succinate). The extracellular matrix is involved in hypoxia-induced retinal neovascularization. Vasorepulsive molecules (semaphorin 3A) intervene preventing the revascularization of the avascular zone. This review focuses on current concepts about signaling pathways and their mediators, involved in the pathogenesis of ROP, highlighting new potentially preventive and therapeutic modalities. A better understanding of the intricate molecular mechanisms underlying the pathogenesis of ROP should allow the development of more effective and targeted therapeutic agents to reduce aberrant vasoproliferation and facilitate physiological retinal vascular development.

La habilidad lingüística en prematuros extremos en edad escolar

En España, el número de nacimientos prematuros es de 30.000, siendo una de las principales causas de mortalidad perinatal. En los últimos años, gracias a los avances médicos, la tasa de supervivencia de esta población se ha visto incrementada, lo cual ha evidenciado la aparición de nuevas morbilidades y comorbilidades que pueden interferir en su proceso de aprendizaje. Este estudio, de carácter cualitativo y longitudinal, cuenta con un muestreo no probabilístico por conveniencia. Su objeto es analizar la habilidad lingüística de cuatro menores grandes prematuros, con una edad gestacional al nacimiento igual o inferior a las 28 semanas, que actualmente cursan 4º de Educación Primaria, para detectar posibles dificultades en la adquisición y en el uso del lenguaje. Se les administró la Batería del Lenguaje Objetiva y Criterial Revisado (BLOC-SR) a la edad cronológica de 8 y 10 años. Los resultados sugieren que existen dificultades en la adquisición de los componentes del lenguaje: en el morfológico, por ejemplo, aparece en el uso de las formas verbales, en los sustantivos derivados, etc.; en el sintáctico, en las oraciones subordinadas de causa y condición, etc.; en el semántico se evidencian en los locativos, etc., y en el pragmático, en la realización de preguntas. A modo de conclusión, los menores prematuros extremos, debido a su condición de vulnerabilidad biológica al quedar interrumpida la maduración cerebral por su nacimiento temprano, necesitan potenciar las destrezas lingüísticas, entre las que destaca la conciencia semántica, siendo necesario diseñar propuestas de intervención para el ámbito escolar.

Retinopathy of prematurity and neurodevelopmental outcomes in preterm infants: A systematic review and meta-analysis

Background

Retinopathy of prematurity (ROP) and abnormal brain development share similar risk factors and mechanisms. There has been contrasting evidence on the association of ROP with adverse neurodevelopmental outcomes.

Objective

We analysed the association between ROP at levels of severity and treatment with all neurodevelopmental outcomes until adolescence.

Data source

We followed PRISMA guidelines and searched Medline and Embase between 1 August 1990 and 31 March 2022.

Study selection and participants

Randomised or quasi-randomised clinical trials and observational studies on preterm infants (<37 weeks) with ROP [type 1 or severe ROP, type 2 or milder ROP, laser or anti-vascular endothelial growth factor (VEGF) treated] were included.

Data extraction and synthesis

We included studies on ROP and any neurocognitive or neuropsychiatric outcomes.

Outcomes

The primary outcomes were as follows: cognitive composite scores evaluated between the ages of 18 and 48 months by the Bayley Scales of Infant and Toddler Development (BSID) or equivalent; neurodevelopmental impairment (NDI; moderate to severe NDI or severe NDI), cerebral palsy, cognitive impairment; and neuropsychiatric or behavioural problems. The secondary outcomes were as follows: motor and language composite scores evaluated between the ages of 18 and 48 months by BSID or equivalent; motor/language impairment; and moderate/severe NDI as defined by the authors.

Results

In preterm infants, "any ROP" was associated with an increased risk of cognitive impairment or intellectual disability [n = 83,506; odds ratio (OR): 2.56; 95% CI: 1.40-4.69; p = 0.002], cerebral palsy (n = 3,706; OR: 2.26; 95% CI: 1.72-2.96; p < 0.001), behavioural problems (n = 81,439; OR: 2.45; 95% CI: 1.03-5.83; p = 0.04), or NDI as defined by authors (n = 1,930; OR: 3.83; 95% CI: 1.61-9.12; p = 0.002). Type 1 or severe ROP increased the risk of cerebral palsy (OR: 2.19; 95% CI: 1.23-3.88; p = 0.07), cognitive impairment or intellectual disability (n = 5,167; OR: 3.56; 95% CI: 2.6-4.86; p < 0.001), and behavioural problems (n = 5,500; OR: 2.76; 95% CI: 2.11-3.60; p < 0.001) more than type 2 ROP at 18-24 months. Infants treated with anti-VEGF had higher odds of moderate cognitive impairment than the laser surgery group if adjusted data (gestational age, sex severe intraventricular haemorrhage, bronchopulmonary dysplasia, sepsis, surgical necrotising enterocolitis, and maternal education) were analysed [adjusted OR (aOR): 1.93; 95% CI: 1.23-3.03; p = 0.04], but not for cerebral palsy (aOR: 1.29; 95% CI: 0.65-2.56; p = 0.45). All outcomes were adjudged with a "very low" certainty of evidence.

Conclusion and relevance

Infants with "any ROP" had higher risks of cognitive impairment or intellectual disability, cerebral palsy, and behavioural problems. Anti-VEGF treatment increased the risk of moderate cognitive impairment. These results support the association of ROP and anti-VEGF treatment with adverse neurodevelopmental outcomes.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42022326009.

Pulmonary Hypertension in Preterm Infants Treated With Laser vs Anti-Vascular Endothelial Growth Factor Therapy for Retinopathy of Prematurity

Importance

Anti-vascular endothelial growth factor (VEGF) therapy for retinopathy of prematurity (ROP) has potential ocular and systemic advantages compared with laser, but we believe the systemic risks of anti-VEGF therapy in preterm infants are poorly quantified.

Objective

To determine whether there was an association with increased risk of pulmonary hypertension (PH) in preterm infants with ROP following treatment with anti-VEGF therapy as compared with laser treatment.

Design, Setting, and Participants

This multicenter retrospective cohort study took place at neonatal intensive care units of 48 children's hospitals in the US in the Pediatric Health Information System database from 2010 to 2020. Participants included preterm infants with gestational age at birth 22 0/7 to 31 6/7 weeks who had ROP treated with anti-VEGF therapy or laser photocoagulation.

Exposures

Anti-VEGF therapy vs laser photocoagulation.

Main Outcomes and Measures

New receipt of pulmonary vasodilators at least 7 days after ROP therapy was compared between exposure groups, matched using propensity scores generated from preexposure variables, and adjusted for birth year and hospital. The odds of receiving an echocardiogram after 30 days of age was also included to adjust for secular trends and interhospital variation in PH screening.

Results

Among 1577 patients (55.9% male) meeting inclusion criteria, 689 received laser photocoagulation and 888 received anti-VEGF treatment (95% bevacizumab, 5% ranibizumab). Patients were first treated for ROP at median 36.4 weeks' postmenstrual age (IQR, 34.6-38.7). A total of 982 patients (491 in each group) were propensity score matched. Good covariate balance was achieved, as indicated by a model variance ratio of 1.15. More infants who received anti-VEGF therapy were treated for PH, but when adjusted for hospital and year, this was no longer statistically significant (6.7%; 95% CI, 2.6-6.9 vs 4.3% 95% CI, 4.4-10.2; adjusted odds ratio, 1.62; 95% CI, 0.90-2.89; P = .10).

Conclusions and Relevance

Anti-VEGF therapy was not associated with greater use of pulmonary vasodilators after adjustment for hospital and year. Our findings suggest exposure to anti-VEGF may be associated with PH, although we cannot exclude the possibility of residual confounding based on systemic comorbidities or hospital variation in practice. Future studies investigating this possible adverse effect seem warranted.

A comparison of primary laser versus laser after anti-vascular endothelial growth factor for type 1 retinopathy of prematurity

PURPOSE

To compare characteristics of laser treatment for high-risk type 1 retinopathy of prematurity (ROP) in eyes treated with primary laser versus laser after an initial treatment with intravitreal anti-vascular endothelial growth factor (anti-VEGF).

METHODS

The medical records of consecutive patients at a single academic institution treated for type 1 ROP before 36 weeks' postmenstrual age with primary laser versus laser after initial treatment with anti-VEGF were reviewed retrospectively. Outcome measures were laser spot number, mean laser power, total laser energy (Joules), and retinal vascularization to the nasal ora at time of laser treatment.

RESULTS

Compared with the 46 eyes treated with primary laser, the 46 eyes treated with laser after anti-VEGF required fewer spots (mean, 775 vs 1418 [P < 0.01]), less power (182 vs 223 mW [P < 0.01]), and less total energy (27 vs 61 Joules [P < 0.01]), and showed greater vascularization to the nasal ora at the time of laser treatment (47.8% vs 6.5% [P < 0.01]).

CONCLUSIONS

In our study cohort, laser after initial anti-VEGF treatment may have allowed for greater retinal vascularization and been less destructive than primary laser for high-risk type 1 ROP.

A systematic review and meta-analysis of preanalytical factors and methodological differences influencing the measurement of circulating vascular endothelial growth factor

Background

Intraocular treatment with antibodies targeting vascular endothelial growth factor (anti-VEGF) inhibits pathological vessel growth in adults and preterm infants. Recently, concerns regarding the impact of anti-VEGF treatment on systemic VEGF levels in preterm infants have been raised. Earlier studies suggest that preanalytical and methodological parameters impact analytical VEGF concentrations, but we have not found a comprehensive systematic review covering preanalytical procedures and methods for VEGF measurements.

Objective

This review aimed to evaluate the most critical factors during sample collection, sample handling, and the analytical methods that influence VEGF levels and therefore should be considered when planning a prospective collection of samples to get reproducible, comparable results.

Material and methods

PubMed and Scopus databases were searched 2021/Nov/11. In addition, identification of records via other methods included reference, citation, and Google Scholar searches. Rayyan QCRI was used to handle duplicates and the selection process. Publications reporting preanalytical handling and/or methodological comparisons using human blood samples were included. Exclusion criteria were biological, environmental, genetic, or physiological factors affecting VEGF. The data extraction sheets included bias assessment using the QUADAS-2 tool, evaluating patient selection, index-test, reference standard, and flow and timing. Concentrations of VEGF and results from statistical comparisons of analytical methods and/or preanalytical sample handling and/or different sample systems were extracted. The publications covering preanalytical procedures were further categorized based on the stage of the preanalytical procedure. Meta-analysis was used to visualize VEGF concentrations among healthy individuals. The quality of evidence was rated according to GRADE.

Results

We identified 1596 publications, and, after the screening process, 43 were considered eligible for this systematic review. The risk of bias estimation was difficult for 2/4 domains due to non-reported information. Four critical steps in the preanalytical process that impacted VEGF quantification were identified: blood drawing and the handling before, during, and after centrifugation. Sub-categorization of those elements resulted in nine findings, rated from moderate to very low evidence grade. The choice of sample system was the most reported factor. VEGF levels (mean [95% CI]) in serum (n = 906, 20 publications), (252.5 [213.1–291.9] pg/mL), were approximated to ninefold higher than in plasma (n = 1122, 23 publications), (27.8 [23.6–32.1] pg/mL), based on summarized VEGF levels with meta-analysis. Notably, most reported plasma levels were below the calibration range of the used method.

Conclusion

When measuring circulating VEGF levels, choice of sample system and sample handling are important factors to consider for ensuring high reproducibility and allowing study comparisons. Protocol: CRD42020192433

Neurovascular abnormalities in retinopathy of prematurity and emerging therapies

Blood vessels in the developing retina are formed in concert with neural growth, resulting in functional neurovascular network. Disruption of the neurovascular coordination contributes to the pathogenesis of retinopathy of prematurity (ROP), a potentially blinding retinal neovascular disease in preterm infants that currently lacks an approved drug therapy in the USA. Despite vasculopathy as predominant clinical manifestations, an increasing number of studies revealed complex neurovascular interplays among neurons, glial cells and blood vessels during ROP. Coordinated expression of glia-derived vascular endothelial growth factor (VEGF) in spatio-temporal gradients is pivotal to the formation of well-organized vascular plexuses in the healthy retina, whereas uncoordinated VEGF expression triggers pathological angiogenesis with disorganized vascular tufts in ROP. In contrast with VEGF driving both pathological and physiological angiogenesis, neuron-derived angiogenic factor secretogranin III (Scg3) stringently regulates ROP but not healthy retinal vessels in animal models. Anti-VEGF and anti-Scg3 therapies confer similar high efficacies to alleviate ROP in preclinical studies but are distinct in their disease selectivity and safety. This review discusses neurovascular communication among retinal blood vessels, neurons and glial cells during retinal development and ROP pathogenesis and summarizes the current and emerging therapies to address unmet clinical needs for the disease.

Association of Docosahexaenoic Acid and Arachidonic Acid Serum Levels With Retinopathy of Prematurity in Preterm Infants

IMPORTANCE

Supplementing preterm infants with long-chain polyunsaturated fatty acids (LC-PUFA) has been inconsistent in reducing the severity and incidence of retinopathy of prematurity (ROP). Furthermore, few studies have measured the long-term serum lipid levels after supplementation.

OBJECTIVE

To assess whether ROP severity is associated with serum levels of LC-PUFA, especially docosahexaenoic acid (DHA) and arachidonic acid (AA), during the first 28 postnatal days.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study analyzed the Mega Donna Mega study, a randomized clinical trial that provided enteral fatty acid supplementation at 3 neonatal intensive care units in Sweden. Infants included in this cohort study were born at a gestational age of less than 28 weeks between December 20, 2016, and August 6, 2019.

MAIN OUTCOMES AND MEASURES

Severity of ROP was classified as no ROP, mild or moderate ROP (stage 1-2), or severe ROP (stage 3 and type 1). Serum phospholipid fatty acids were measured through gas chromatography-mass spectrometry. Ordinal logistic regression, with a description of unadjusted odds ratio (OR) as well as gestational age- and birth weight-adjusted ORs and 95% CIs, was used. Areas under the curve were used to calculate mean daily levels of fatty acids during postnatal days 1 to 28. Blood samples were obtained at the postnatal ages of 1, 3, 7, 14, and 28 days.

RESULTS

A total of 175 infants were included in analysis. Of these infants, 99 were boys (56.6%); the median (IQR) gestational age was 25 weeks 5 days (24 weeks 3 days to 26 weeks 6 days), and the median (IQR) birth weight was 785 (650-945) grams. A higher DHA proportion was seen in infants with no ROP compared with those with mild or moderate ROP or severe ROP (OR per 0.5-molar percentage increase, 0.49 [95% CI, 0.36-0.68]; gestational age- and birth weight-adjusted OR, 0.66 [95% CI, 0.46-0.93]). The corresponding adjusted OR for AA levels per 1-molar percentage increase was 0.83 (95% CI, 0.66-1.05). The association between DHA levels and ROP severity appeared only in infants with sufficient AA levels, suggesting that a mean daily minimum level of 7.8 to 8.3 molar percentage of AA was necessary for a detectable association between DHA level and less severe ROP.

CONCLUSIONS AND RELEVANCE

This cohort study found that higher mean daily serum levels of DHA during the first 28 postnatal days were associated with less severe ROP even after adjustment for known risk factors, but only in infants with sufficiently high AA levels. Further studies are needed to identify LC-PUFA supplementation strategies that may prevent ROP and other morbidities.