P Score: A Reference Image-Based Clinical Grading Scale for Vascular Change in Retinopathy of Prematurity
Gil Binenbaum, Andreas Stahl, Aaron S. Coyner, Jocelyn He, Gui‐Shuang Ying, Susan Ostmo, R.V. Paul Chan, Cynthia A. Toth, Anand Vinekar, J. Peter Campbell, Michael F. Chiang, Graham E. Quinn, Alistair R. Fielder, Susan Ostmo, R.V. Paul Chan, Audina M. Berrocal, Gil Binenbaum, Michael P. Blair, J. Peter Campbell, Antonio Capone, Yi Chen, Shuan Dai, Anna L. Ells, Brian W. Fleck, William V. Good, M. Elizabeth Hartnett, Gerd Holmström, Shunji Kusaka, Andrés Kychenthal, Domenico Lepore, Birgit Lorenz, María Ana Martinez-Castellanos, Şengu ̈l O ̈zdek, Dupe Ademola-Popoola, James D. Reynolds, Parag K. Shah, Michael J. Shapiro, Andreas Stahl, Cynthia A. Toth, Anand Vinekar, Linda Visser, David K. Wallace, Wei-Chi Wu, Peiquan Zhao, Andréa Zin, Francine Baran, Gerard P. Barry, Audina M. Berrocal, Amit Bhatt, Gil Binenbaum, Michael P. Blair, J. Peter Campbell, Shuan Dai, Bradley V. Davitt, Alejandra de Alba Campomanes, Amgad Eldib, Alistair R. Fielder, Brian W. Fleck, Brooke Geddie, Kathryn M. Haider, M. Elizabeth Hartnett, Gerd Holmström, Anne K. Jensen, Monica Khitri, Shunji Kusaka, María Ana Martinez-Castellanos, Susan Ostmo, Dupe Ademola-Popoola, Matthew S. Pihlblad, Graham E. Quinn, Michael X. Repka, Shira L. Robbins, Sarah Hilkert Rodriguez, Parag K. Shah, Andreas Stahl
Abstract
PURPOSE: The International Classification of Retinopathy of Prematurity, Third Edition (ICROP3), acknowledged that plus-like retinopathy of prematurity (ROP) vascular changes occurs along a spectrum. Historically, clinician-experts demonstrate variable agreement for plus diagnosis. We developed a 9-photograph reference image set for grading plus-like changes and compared intergrader agreement of the set with standard grading with no plus, preplus, and plus disease. DESIGN: Retinal photographic grading and expert consensus opinion. PARTICIPANTS: The development set included 34 international ICROP3 committee members. The validation set included 30 ophthalmologists with ROP expertise (15 ICROP3 committee members and 15 non-ICROP3 members) METHODS: Nine ROP fundus images (P1 through P9) representing increasing degrees of zone I vascular tortuosity and dilation, based on the 34 ICROP3 committee members' gradings and consensus image reviews, were used to establish standard photographs for the plus (P) score. Study participants graded 150 fundus photographs 2 ways, separated by a 1-week washout period: (1) no plus, preplus, or plus disease and (2) choosing the closest P score image. MAIN OUTCOME MEASURES: Intergrader agreement measured by intraclass correlation coefficient. RESULTS: Intergrader agreement was higher using the P score (intraclass correlation coefficient, 0.75; 95% confidence interval, 0.71-0.79) than no plus, preplus, or plus disease (intraclass correlation coefficient, 0.67; 95% confidence interval, 0.62-0.72). Mean ± standard deviation P scores for images with mode gradings of no plus, preplus, and plus disease were 2.5 ± 0.7, 4.8 ± 0.8, and 7.4 ± 0.8, respectively. CONCLUSIONS: Intergrader agreement of plus-like vascular change in ROP using the P score is high. We now incorporate this 9-image reference set into ICROP3 for use in clinician daily practice alongside zone, stage, and plus assessment. P score is not yet meant to replace plus diagnosis for treatment decisions, but its use at our institutions has permitted better comparison between examinations for progression and regression, communication between examiners, and documentation of vascular change without fundus imaging. P score also could provide more detailed ROP classification for clinical trials, consistent with the spectrum of plus-like change that is now formally part of the International Classification of Retinopathy of Prematurity. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.