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.