THROMBOCYTOPENIA AS A RISK FACTOR FOR RETINOPATHY OF PREMATURITY

Platelet Counts and Risk of Severe Retinopathy of Prematurity: A Bayesian Model-Averaged Meta-Analysis

BACKGROUND

We aimed to conduct a systematic review and Bayesian model-averaged meta-analysis (BMA) on the association between platelet counts and severe retinopathy of prematurity (ROP).

METHODS

We searched for studies reporting on platelet counts (continuous variable) or thrombocytopenia (categorical variable) and severe ROP or aggressive posterior ROP (APROP). The timing of platelet counts was divided into Phase 1 (<2 weeks) and Phase 2 (around ROP treatment). BMA was used to calculate Bayes factors (BFs). The BF10 is the ratio of the probability of the data under the alternative hypothesis (H1) over the probability of the data under the null hypothesis (H0).

RESULTS

We included 21 studies. BMA showed an association between low platelet counts and severe ROP. The evidence was strong (BF10 = 13.5, 7 studies) for phase 1 and very strong (BF10 = 51.0, 9 studies) for phase 2. Thrombocytopenia (<100 × 109/L) in phase 2 was associated with severe ROP (BF10 = 28.2, 4 studies). Following adjustment for publication bias, only the association of severe ROP with thrombocytopenia remained with moderate evidence in favor of H1 (BF10 = 4.30).

CONCLUSIONS

Thrombocytopenia is associated with severe ROP. However, the evidence for this association was tempered when results were adjusted for publication bias.

A novel marker for predicting type 1 retinopathy of prematurity: C-reactive protein/albumin ratio

PURPOSE

We aimed to investigate whether the C-reactive protein (CRP) to albumin ratio (CAR) an inflammatory predictor can be used as a marker for the development of ROP.

METHODS

Gestational age, birth weight, gender, neonatal, and maternal risk factors were recorded. The patients were divided into two groups: those who did not develop ROP (ROP -) and those who developed ROP (ROP +). The ROP + group was further separated into two groups: those who required treatment (ROP + T) and those who were not treated (ROP + NT). The following parameters were noted in the first postnatal week and at the end of the first postnatal month: CRP, albumin, CAR, white blood cell (WBC), neutrophil, lymphocyte, neutrophil-to-lymphocyte ratio (NLR), distribution red cell width (RDW), platelet (Plt), and RDW/platelet ratio.

RESULTS

We evaluated 131 premature infants who met the inclusion criteria. There was no difference between the main groups in hemogram parameters and CAR at the postnatal first week. WBC count (p = 0.011), neutrophil count (p = 0.002), and NLR were high (p = 0.004) in the ROP + group at the end of the postnatal 1st month. The CAR level at the end of the first month was higher in the ROP + group (p = 0.027). CAR was similar between the ROP + T and ROP + NT groups (p = 0.112) in the postnatal first week but higher in the treatment-required group at the end of the first month (p < 0.01).

CONCLUSION

High CAR and high NLR at the end of the postnatal first month can be used to predict the development of severe ROP.

Is thrombocytopenia and postnatal weight gain associated with treatment‐requiring retinopathy of prematurity? A matched case–control study

PURPOSE

The purpose of the study was to investigate the association of platelet parameters and postnatal weight gain with treatment-requiring ROP (TR-ROP).

METHODS

In this retrospective matched case-control study, infants with TR-ROP were individually matched, according to gestational age and birth weight, with one or two untreated infants who developed no or spontaneously regressed ROP. Longitudinal data on platelet count (PLT), mean platelet volume (MPV), daily weight and platelet transfusions were collected. Platelet mass index (PMI) and weight standard deviation score (WSDS) were also calculated. Conditional logistic regression analysis was performed to adjust for matching.

RESULTS

Fourteen cases, presenting type I ROP, and 25 matched controls were included. The odds of developing TR-ROP decreased as PLT increased during 31^st week of postmenstrual age (PMA) or during 1^st and 2^nd week of postnatal age (PNA). The odds of developing TR-ROP were 16.7 times higher in infants receiving at least one platelet transfusion compared with those who were not transfused. The odds of developing TR-ROP increased by 31.2% as the mean volume of platelet transfusion per infant increased by 1 ml. The odds of developing TR-ROP decreased as PMI increased during 1^st week PNA, and as weight and WSDS increased during 4^th -6^th week PNA. Analysis of MPV, number of thrombopenic episodes per infant, number of platelet transfusions per infant and days with WSDS < -2 showed no association with TR-ROP.

CONCLUSION

To our knowledge, this is the first study ascertaining an association of platelet transfusions with type I ROP. Prospective cohort studies are required to confirm our findings.

Association of platelet deficiency with severe retinopathy of prematurity: a review

AIM

The aim of this review was to compile existing evidence on the role of platelets in the development of severe retinopathy of prematurity (ROP), highlight the strengths and weaknesses of the available studies and critically discuss the reported data.

METHODS

A comprehensive literature search was conducted on PubMed from January 2000 to January 2022, and the reference lists of the included studies were screened manually.

RESULTS

There were 19 primary studies that fulfilled the eligibility criteria. Experimental research indicated lower platelet count in mice oxygen-induced retinopathy model compared with normoxia controls, while platelet transfusions suppressed neovascularisation. The latter finding was not consistently confirmed in clinical research, where a low platelet count, an increased number of thrombopenic episodes and of platelet transfusions have all been implicated in the development of ROP requiring treatment, either type I or aggressive posterior or both. However, existing studies exhibit significant clinical heterogeneity and present methodological limitations that imperil their reliability and validity.

CONCLUSION

Platelet deficiency has been associated with severe ROP. However, critical thresholds of platelet parameters are still unrecognised. Future research is required to determine whether platelet parameters can be predictive biomarkers for ROP requiring treatment and at what thresholds.

Platelet is the early predictor of bronchopulmonary dysplasia in very premature infants: an observational cohort study

Background

A previous study showed that the lungs are involved in the biogenesis of platelets (PLTs). Thus, the present study aimed to investigate the association between bronchopulmonary dysplasia (BPD), a chronic lung disease, and PLT parameters in very premature infants.

Methods

The study subjects were premature infants with a gestational age of ≤ 30 weeks and birth weight of ≤ 1500 g in a preterm birth cohort study recruited between January 1, 2015, and August 31, 2019. BPD was defined as the need for oxygen supplementation more than 28 days after birth. The PLT count, mean platelet volume (MPV), platelet distribution width (PDW), and plateletcrit (PCT) level were compared between BPD and non-BPD infants. A generalized estimating equation model was used to adjust for confounding factors. A forward stepwise logistic regression model was used to calculate the adjusted odds ratio (OR) for thrombocytopenia in the BPD group. Receiver operating characteristic curve analysis was performed to assess the predictive value of PLT count combined with gestational age (GA) and birth weight (BW) for BPD.

Results

The final study subjects were 134 very premature infants, namely, 64 infants with BPD and 70 infants without BPD. The BPD infants had lower PLT counts (F = 4.44, P = 0.03) and PCT levels (F = 12.54, P = 0.00) than the non-BPD infants. However, the MPV (F = 14.25, P = 0.00) and PDW (F = 15.04, P = 0.00) were higher in the BPD group. After adjusting for potential confounding factors, the BPD infants had a higher risk of thrombocytopenia than the non-BPD infants (adjusted aOR 2.88, 95% CI 1.01–8.15), and the risk of BPD was increased in very premature infants with a PLT count ≤ 177*10⁹/L (OR 4.74, 95% CI 1.93–11.62) at the end of the second week. In the multivariate predictive model, it was showed that the AUC area (0.85), sensitivity (0.88), specificity (0.70) and Youden index (0.58) are improved using PLT counts ≤ 177*10⁹/L combined with GA and BW.

Conclusions

Abnormal PLT parameters were observed in BPD infants, and a PLT count ≤ 177*10⁹/L was a potential risk factor for the development of BPD in very premature infants.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01895-2.

The Role of Thrombocyte Parameters in Retinopathy of Prematurity Development

PURPOSE

To investigate the role of thrombocyte parameters in retinopathy of prematurity (ROP) development.

MATERIALS AND METHODS

This retrospective study included 120 preterm infants in total. Group 1 was formed by infants who developed type-1 ROP and received treatment. Group 2 was formed by infants who developed ROP and were not treated for ROP. Infants who did not develop ROP and whose retinal vascularization was completed in their follow-up formed Group 3. Gestational age, birth weight, and genders of groups were recorded. Platelet (PLT) count, mean platelet volume (MPV), and platelet distribution width (PDW) values were obtained from complete blood count. Platelet mass index (PMI) was calculated by multiplying the PLT count by MPV value. Thrombocytopenia was defined as PLT count <150 × 1000/μL. All parameters were compared between the groups.

RESULTS

There were 40 preterm infants in each group. The mean PLT count was 272.43 ± 122.67 in Group 1, 333.32 ± 133.06 in Group 2, and 310.03 ± 119.41 in Group 3. The difference in PLT count between the groups was not significant (p=0.094). Thrombocytopenia was observed in 25% of Group 1, 10% of Group 2, and 10% of Group 3 (p=0.095). No statistically significant difference was found in terms of MPV, PDW, and PMI values between the groups (p=0.102, p=0.097, and p=0.298, respectively).

CONCLUSIONS

Although PLT count was lower and thrombocytopenia rate was higher in the type-1 ROP group, the differences were not found to be significant. Further prospective studies are required to evaluate the role of thrombocytes in ROP pathogenesis.

Thrombocytopenia as Type 1 ROP Biomarker: A Longitudinal Study

This study aimed to prospectively evaluate the association between the appearance and evolution of retinopathy of prematurity (ROP) and selected blood parameters, focusing on platelets count. In total, 157 preterm consecutive babies screened for ROP were included and classified in: ROP necessitating treatment (group ROP1), ROP regressed without therapy (group ROP2) and no ROP (group no-ROP), divided in two phases for each group depending on gestational age. Blood parameters were weekly gathered and referred to postmenstrual age, ROP severity and phase. Platelet count mean values were statistically lower (p < 0.001) during both phases in ROP1 group (179 × 10⁹/L vs. 213 × 10⁹/L in phase 1 and 2, respectively) vs. other groups (ROP2: 286 × 10⁹/L vs. 293 × 10⁹/L; no ROP: 295 × 10⁹/L vs. 313 × 10⁹/L). Platelet count at birth <181 × 10⁹ was statistically associated with Type 1 ROP development and evolution (sensibility = 76.47%, 95% confidence interval 60.0–87.6; specificity = 66.12%, 95% confidence interval 57.3–73.9). In ROP 1 group, a platelets count mean value “spike” (392.6 × 109/L) was documented at 36 weeks of corrected gestational age, preceding the need for treatment performed at a median of 38.1 ± 3.2 weeks. Early birth thrombocytopenia is confirmed as a biomarker of development and progression of ROP requiring treatment. The increase of platelets count at 35–37 weeks of corrected gestational age can be considered a possible clinical biomarker anticipating Type 1 ROP progression in preterm infants.

Comparison of Mean Platelet Counts in Preterm Infants with and without Retinopathy of Prematurity

Platelets are a primary source of pro- and anti-angiogenic cytokines. However, the evidence of their role in retinopathy of prematurity (ROP) is controversial. This retrospective study aimed to compare mean weekly platelet counts between infants with and without ROP over the first 6 weeks of life. A total of 93 infants matched by gestational age and birth weight were recruited (31 with ROP, 62 without ROP). Weekly mean platelet counts and other related risk factors were documented. The repeated measure analysis of variance (ANOVA) and the repeated measure analysis of covariance (ANCOVA) were used to compare mean platelet counts over time between the two groups, with and without adjusting for confounders. We found significant differences in the weekly mean platelet counts of infants with and without ROP over the first 6 weeks of life (p = 0.002). These differences disappeared after adjusting for covariates (p = 0.489). Lower mean platelet counts in ROP infants are not directly related to ROP, but rather to the presence of other risk factors for ROP, such as culture-proven sepsis, blood transfusion and bronchopulmonary dysplasia.

Complete blood count parameters to predict retinopathy of prematurity: when to evaluate and what do they tell us?

PURPOSE

To evaluate the relationship of novel inflammatory markers neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) with retinopathy of prematurity (ROP) development and requirement for laser photocoagulation (LP) treatment.

METHODS

The charts of infants screened for ROP were reviewed retrospectively, and 120 newborns who had complete blood count (CBC) data in the first 24 hours after delivery (early period) and between 35 and 37th gestational weeks (late period) were included. Study population consisted of 34 infants who required LP for ROP treatment, 52 newborns with ROP that regressed without treatment, and 34 controls who did not developed any ROP stages. Demographics, etiological factors and CBC data including NLR and PLR values were noted. Risk factors for ROP development and treatment requirement were investigated using logistic regression analyses.

RESULTS

Significantly lower NLR was found in ROP cases compared to non-ROP group during late period (p = 0.003), while there was no difference in NLR during early period (p = 0.298). No significant difference was observed in PLR during both early and late periods (p = 0.230 and p = 0.349, respectively). Multivariate analysis revealed daily weight gain as major risk factor for ROP development (p = 0.001; OR: 0.870, 95% CI: 0.799-0.947), and hyperbilirubinemia as an independent risk factor for LP requirement (p = 0.045; OR: 0.204, 95% CI: 0.043-0.966).

CONCLUSION

NLR or PLR does not appear to be predictive risk factors for treatment requirement in cases with ROP. CBC values during first 24 h of life may be misleading; therefore, a late period CBC is recommended to evaluate prognostic factors for ROP development.

Decreased Platelet Counts and Serum Levels of VEGF-A, PDGF-BB, and BDNF in Extremely Preterm Infants Developing Severe ROP

INTRODUCTION

Thrombocytopenia has been identified as an independent risk factor for retinopathy of prematurity (ROP), although underlying mechanisms are unknown. In this study, the association of platelet count and serum platelet-derived factors with ROP was investigated.

METHODS

Data for 78 infants born at gestational age (GA) <28 weeks were included. Infants were classified as having no/mild ROP or severe ROP. Serum levels of vascular endothelial growth factor A, platelet-derived growth factor BB, and brain-derived neurotrophic factor were measured in serum samples collected from birth until postmenstrual age (PMA) 40 weeks. Platelet counts were obtained from samples taken for clinical indication.

RESULTS

Postnatal platelet counts and serum concentrations of the 3 growth factors followed the same postnatal pattern, with lower levels in infants developing severe ROP at PMA 32 and 36 weeks (p < 0.05-0.001). With adjustment for GA, low platelet counts and low serum concentrations of all 3 factors at PMA 32 weeks were significantly associated with severe ROP. Serum concentrations of all 3 factors also strongly correlated with platelet count (p < 0.001).

CONCLUSION

In this article, we show that ROP, platelet counts, and specific pro-angiogenic factors correlate. These data suggest that platelet-released factors might be involved in the regulation of retinal and systemic angiogenesis after extremely preterm birth. Further investigations are needed.

Retinal hemorrhage and bleeding disorders in children: A review

BACKGROUND

Retinal hemorrhages (RH) are a common manifestation of abusive head trauma (AHT) resulting from acceleration-deceleration injury with or without blunt impact. Evaluation of a child with RH requires careful consideration of these differential diagnoses. The extent to which coagulopathy alone can cause RH would be useful to understand as coagulopathy may accompany AHT.

OBJECTIVE

In this systematic review, we sought to identify whether coagulopathies have been reported with RH similar to those of AHT.

METHODS

We performed a literature search for ocular manifestations of bleeding disorders in children less than 18 years old. We included clotting factor deficiencies, vitamin K deficiency, platelet function abnormalities, thrombocytopenia, disseminated intravascular coagulation (DIC), and trauma induced coagulopathy (TIC). We included only pediatric reports of intraocular bleeding or documented eye examinations that indicated no hemorrhages. We then re-examined cases for ocular and systemic findings that could potentially mimic abuse.

RESULTS

Our initial search yielded 816 results. Sixty-one articles met our inclusion criteria. Of these, there were 32 children within the AHT age range (less than 5 years old) who had RH and concomitant coagulopathy. Only 5 cases might potentially be confused for abuse. Of these, no classic characteristics of RH from abuse such as retinoschisis or retinal folds were found. Systemic features were inconsistent with AHT.

CONCLUSIONS

The presence of coagulopathy alone does not rule out the possibility that the child has been abused. Coagulopathy alone has not been reported as an etiology of RH that are consistent with AHT, especially when other findings are present.

Severe retinopathy of prematurity is associated with early post-natal low platelet count

Pathophysiology of retinopathy of prematurity (ROP) still presents a gap. Lately blood tests parameters of premature infants have been measured at different times of ROP, attempting to detect correlations with ROP development and progression. So far, very early post-natal biomarkers, predictive of ROP outcome, have not been detected. Our purpose is to evaluate, in the earliest post birth blood sample, the correlation between routinely dosed blood parameters and ROP outcome. 563 preterm babies, screened according to ROP guidelines, were included and classified in conformity with ET-ROP study in “Group 1” (ROP needing treatment), “Group 2” (ROP spontaneously regressed) and “noROP” group (never developed ROP). The earliest (within an hour after delivery) blood test parameters routinely dosed in each preterm infant were collected. Platelet count was decreased in Group 1 versus noROP group (p = 0.0416) and in Group 2 versus noROP group (p = 0.1093). The difference of thrombocytopenic infants among groups was statistically significant (p = 0.0071). CRP was higher in noROP versus all ROPs (p = 0.0331). First post-natal blood sample revealed a significant thrombocytopenia in ROP needing treatment, suggesting a role of platelets in the pathophysiology and progression of ROP, possibly considering it as a predictive parameter of ROP evolution.

Associations between Red Blood Cell and Platelet Transfusions and Retinopathy of Prematurity

AIM

The aim of this study is to examine possible associations between the transfusion of RBC or platelets (PLTs) and the development of retinopathy of prematurity (ROP) in infants.

METHODS

This retrospective, national, case-control study included all live births in Switzerland between 2013 and 2018. We investigated preterm infants at a gestational age of <28 weeks, who developed higher stage ROP (≥stage 2, n = 178). Each case infant was matched to another of the same sex who did not develop ROP (n = 178, control group).

RESULTS

When compared with the control group, we observed higher numbers of RBC transfusions per infant and higher percentages of infants receiving PLT transfusions in the case group. An adjusted logistic regression analysis revealed that both RBC (odds ratio [OR] 1.081, 95% confidence interval [CI] 1.020-1.146) and PLT transfusions (OR = 2.502, 95% CI 1.566-3.998) numbers were associated with ROP development.

CONCLUSIONS

Multiple RBC and PLT transfusions are associated with higher stage ROP development. Prospective studies are required to determine their potential as risk factors.

Platelet transfusion for neonates with thrombocytopaenia: protocol for a systematic review

INTRODUCTION

Thrombocytopaenia is one of the most common haemostatic abnormalities among neonates. It affects approximately one-quarter of neonates admitted into neonatal intensive care units and may lead to a high risk of bleeding and mortality, which are substantial causes for concern by neonatologists. Platelet transfusion (PT) is a specific treatment for thrombocytopaenia. To date, PT thresholds are diverse since the associations between low platelet count and negative outcomes are not clear. We propose this protocol for a systematic review to collect and assess evidence concerning the best PT threshold to reduce mortality, bleeding and major morbidity among neonates with thrombocytopaenia.

METHODS AND ANALYSIS

The systematic review will be performed according to the Cochrane Handbook for Systematic Review of Interventions, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, and the Grading of Recommendations Assessment, Development and Evaluation system. Two independent researchers will perform the study selection, data extraction/coding, quality assessment and further analyses of the included studies, with disagreements being resolved by a third researcher. A systematic search of the literature will be conducted in the PubMed, Cochrane Library and Embase databases from database inception through 13 October 2020. All randomised controlled trials, cohort studies and case-control studies will be included without any restrictions regarding publication date or language. The primary outcomes will comprise in-hospital mortality and bleeding episodes. Endnote X9 and Review Manager V.5.3 software will be used to manage the selection process and statistical analysis, respectively. If the included studies are sufficient and homogeneous for any of the outcomes, a quantitative synthesis (meta-analysis) may be performed. Otherwise, we will conduct a narrative systematic review of the results.

ETHICS AND DISSEMINATION

Ethical approval is not required for this study because the data will be obtained from published studies and will not include individual patient data. The results of this study are anticipated to be published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42020169262.

Thrombocytopenia is associated with severe retinopathy of prematurity

Retinopathy of prematurity (ROP) is characterized by abnormal retinal neovascularization in response to vessel loss. Platelets regulate angiogenesis and may influence ROP progression. In preterm infants, we assessed ROP and correlated with longitudinal postnatal platelet counts (n = 202). Any episode of thrombocytopenia (<100 × 109/l) at ≥30 weeks postmenstrual age (at onset of ROP) was independently associated with severe ROP, requiring treatment. Infants with severe ROP also had a lower weekly median platelet count compared with infants with less severe ROP. In a mouse oxygen-induced retinopathy model of ROP, platelet counts were lower at P17 (peak neovascularization) versus controls. Platelet transfusions at P15 and P16 suppressed neovascularization, and platelet depletion increased neovascularization. Platelet transfusion decreased retinal of vascular endothelial growth factor A (VEGFA) mRNA and protein expression; platelet depletion increased retinal VEGFA mRNA and protein expression. Resting platelets with intact granules reduced neovascularization, while thrombin-activated degranulated platelets did not. These data suggest that platelet releasate has a local antiangiogenic effect on endothelial cells to exert a downstream suppression of VEGFA in neural retina. Low platelet counts during the neovascularization phase in ROP is significantly associated with the development of severe ROP in preterm infants. In a murine model of retinopathy, platelet transfusion during the period of neovascularization suppressed retinopathy.