The data of 348 infants that were referred to the Ophthalmology Unit of Erzincan University, Turkey between June 2018 and July 2019 for the screening of ROP were retrospectively analyzed. A total of 167 patients, from whom CBC samples were collected within the first 72 hours after birth and who met the inclusion criteria were included in the study. Fifty-nine patients were found to have ROP on the first examination, but none had the severe form of the disease. This study was created in accordance with the Declaration of Helsinki, and verbal informed consent was taken from the parents of each patient before the study. All infants were participants who applied for ROP screening and had blood tests available. Performing the study no extra blood sample were needed and all of the parents accept including in the study of the babies. All the infants had CBC samples which were collected in intensive care unit for newborns. The approval of the Institutional Ethics Committee of Erzincan University was also obtained.
Infants with a smaller gestational age than 35 weeks were examined for ROP after administering tropicamide 1% (Tropamid®, Bilimilaç®,Gebze, Turkey) eye drops and phenylephrine hydrochloride 0.5% (Mydfrin®, Alcon®, Fort Worth, TX) eye drops for three times for pupillary dilatation. The ROP examination was performed by the same experienced eye professional using a binocular indirect ophthalmoscope combined with a sclera depressor after administering proparacaine hydrochloride 0.5% (Alcaine®, Alcon®, Fort Worth, TX)eye drops as the topical anesthetic. The ROP status was graded according to the international classification of ROP in all infants. The ROP status was noted including the stage, zone and extent of the disease, and the presence or absence of plus disease for each infant.12 Each infant was also graded according to the maximum stage of ROP examined in either eye.
All blood samples were gathered and investigated within the first 72 h after birth. Peripheral venous blood samples (1 mL) was gathered in tubes containing dipotassium ethylenediamine tetraacetate (EDTA–2K). CBC were investigated by an automated hematology analyzer. (Sysmex Corporation, Kobe 651–0073, Japan). The NLR values were figured out by dividing the neutrophil count to the lymphocyte count, the PLR values by dividing the platelet count to the lymphocyte count, and the MLR values by dividing the monocyte count to the lymphocyte count.
The patients were seperated into two groups: Group 1 comprised those with the diagnosis of ROP and Group 2 consisted of patients without ROP. All patients accepted in the study were evaluated by fundoscopic examination at four weeks after birth. The patients were called for a control visit at an appropriate time according to the stage and zone of ROP (after one, two, three or four weeks. Retinal vascularization reached the ora serrata in the follow-up of all the patients.
Infants born with hematologic disorders, received postnatal steroid therapy or a blood product transfusion before the ROP examination were excluded from the study. And also patients with respiratory distress syndrome (RDS), asphyxia neonatorum, neonatal pneumonia, premature rupture of membranes (PROM), necrotizing enterocolitis, hypoxic-ischemic encephalopathy (HIE) and blood culture-proven sepsis were excluded from the study. Infants who did not attend follow-up regularly and who had any other accompanying ocular or systemic diseases were excluded from the study.
The SPSS (Statistical Package for the Social Sciences) version 22.0 statistical software package was used for statistical analyses. The Kolmogorov-Smirnov test was applied to observe the distribution of the parameters in the study groups. Continuous variables were expressed as mean ± standard deviation (SD), and categorical variables as frequencies and percentages. The chi-square test was used to analyze the categorical variables. Inter-group comparisons of the continuous variables were performed using Student’s t-test in addition to the analysis of variation (ANOVA) for homogenous data and the Mann-Whitney U test for non-homogenous data. The Friedman variance analysis test was performed to compare the variables in repeated measures, Wilcoxon’s signed rank test for the pairwise comparisons of these variables, and the Pearson and Spearman correlation tests for the assessment of the correlations between the variables. Logistic regression analysis was performed to predict the significant independent risk factors associated with the existence of ROP. Exact P values of <0.05 were considered statistically significant. The adjusted odds ratio (OR) and the 95% confidence interval (CI) for each possible risk factor were calculated. A receiver operating characteristic (ROC) curve analysis was applied to define the cut-off values of NLR and PLR in predicting the stage of ROP. All of the results were appraised at a confidence interval of 95% based on a significance level of P < 0.05.