<scp>THESS</scp> ‐ <scp>ROP</scp> study: Development of a prediction model for treatment‐warranted retinopathy of prematurity and external validation of postnatal weight‐gain‐based models in Greece

PURPOSE: To develop THESS-ROP, a novel prediction model for treatment-warranted retinopathy of prematurity (TW-ROP) and compare its performance with four established models in a Greek cohort of consecutively screened preterm infants. METHODS: This ambispective cohort study included all 526 infants screened for ROP (2016-2022) at the 2nd Neonatology Department of Aristotle University of Thessaloniki, a tertiary neonatal intensive care unit in Greece. The primary outcome was TW-ROP (type 1 or 2 or aggressive ROP). Secondary outcomes included type 1 ROP and ROP treatment. A penalized ridge logistic regression model was developed using gestational age, birth weight, sepsis, and hydrocephalus up to 4 weeks postnatal age. Missing data were addressed using 10-fold multiple imputation. Internal validation used bootstrap resampling with optimism correction. External validation of CO-ROP, G-ROP, G-ROP 180 g, and ROPScore was performed in the same cohort. Performance was assessed using area under the curve (AUC), sensitivity, specificity, positive predictive value, and negative predictive value. RESULTS: TW-ROP developed in 34 infants (6.5%; 24 type 1, 10 type 2), with 29 receiving treatment. THESS-ROP demonstrated excellent discrimination [optimism-corrected AUC 0.935, 95% CI (0.905-0.965)], pooled sensitivity 98.0% and pooled specificity 58.0%. Sensitivity reached 100% for type 1 ROP and treated ROP. In external validation, CO-ROP, G-ROP, G-ROP 180 g, and ROPScore achieved pooled sensitivities of 90.9%, 98.8%, 98.8%, and 100.0% with specificities of 63.4%, 34.4%, 26.1%, and 62.1%, respectively. CONCLUSION: THESS-ROP model, incorporating easily available clinical data, enables effective early risk stratification at 4 weeks PNA and may optimize ROP screening. External validation in independent populations is required before clinical implementation.