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Original Investigation
July 13, 2017

Validation of the Children’s Hospital of Philadelphia Retinopathy of Prematurity (CHOP ROP) Model

Gil Binenbaum, MD, MSCE1,2; Gui-shuang Ying, PhD2; Lauren A. Tomlinson, BS1; et al for the Postnatal Growth and Retinopathy of Prematurity (G-ROP) Study Group
Author Affiliations
  • 1Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
  • 2Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia
JAMA Ophthalmol. Published online July 13, 2017. doi:10.1001/jamaophthalmol.2017.2295
Key Points

Question  Can the CHOP ROP model be validated in a multicenter cohort large enough to obtain a precise estimate of the model’s sensitivity for treatment-requiring retinopathy of prematurity?

Findings  In this secondary analysis of data from the Postnatal Growth and Retinopathy of Prematurity Study of 7483 premature infants at risk for retinopathy of prematurity, the original CHOP ROP model correctly predicted 452 of 459 infants with type 1 retinopathy of prematurity, reducing the number of infants requiring examinations by 34.3% if only high-risk infants received examinations.

Meaning  These results suggest that the CHOP ROP model has high but not 100% sensitivity and may be better used to reduce examination frequency.

Abstract

Importance  The Children's Hospital of Philadelphia Retinopathy of Prematurity (CHOP ROP) model uses birth weight (BW), gestational age at birth (GA), and weight gain rate to predict the risk of severe retinopathy of prematurity (ROP). In a model development study, it predicted all infants requiring treatment, while greatly reducing the number of examinations compared with current screening guidelines.

Objective  To validate the CHOP ROP model in a multicenter cohort that is large enough to obtain a precise estimate of the model’s sensitivity for treatment-requiring ROP.

Design, Setting, and Participants  This investigation was a secondary analysis of data from the Postnatal Growth and Retinopathy of Prematurity (G-ROP) Study. The setting was 30 hospitals in the United States and Canada between January 1, 2006, and June 30, 2012. The dates of analysis were September 28 to October 5, 2015. Participants were premature infants at risk for ROP with a known ROP outcome.

Main Outcomes and Measures  Sensitivity for Early Treatment of Retinopathy of Prematurity type 1 ROP and potential reduction in the number of infants requiring examinations. In the primary analysis, the CHOP ROP model was applied weekly to predict the risk of ROP. If the risk was above a cut-point level (high risk), examinations were indicated, while low-risk infants received no examinations. In a secondary analysis, low-risk infants received fewer examinations rather than no examinations.

Results  Participants included 7483 premature infants at risk for ROP with a known ROP outcome. Their median BW was 1070 g (range, 310-3000 g), and their median GA was 28 weeks (range, 22-35 weeks). Among them, 3575 (47.8%) were female, and their race/ethnicity was 3615 white (48.3%), 2310 black (30.9%), 233 Asian (3.1%), 93 Pacific Islander (1.2%), and 40 American Indian/Alaskan native (0.5%). The original CHOP ROP model correctly predicted 452 of 459 infants who developed type 1 ROP (sensitivity, 98.5%; 95% CI, 96.9%-99.3%), reducing the number of infants requiring examinations by 34.3% if only high-risk infants received examinations. Lowering the cut point to capture all type 1 ROP cases (sensitivity, 100%; 95% CI, 99.2%-100%) resulted in only 6.8% of infants not requiring examinations. However, if low-risk infants were examined at 37 weeks’ postmenstrual age and followed up only if ROP was present at that examination, all type 1 ROP cases would be captured, and the number of examinations performed among infants with GA exceeding 27 weeks would be reduced by 28.4%.

Conclusion and Relevance  The CHOP ROP model demonstrated high but not 100% sensitivity and may be better used to reduce examination frequency. The model might be used reliably to guide a modified ROP screening schedule and decrease the number of examinations performed.

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