Eyeworld

EW SECONDARY FEATURE 70 by Rich Daly EyeWorld Contributing Editor Effort continues to predict prolific retinopathy The WINROP algorithm may have a role for general ophthalmologists looking to screen infants for the early stages of the blinding condition R outine screening of preterm infants to iden- tify those at risk for reti- nal detachment could take on greater precision with a tool under development and tested in multiple countries. Nearly all children in developed countries are screened for prolific retinopathy based on their develop- mental weight, but greater precision could help narrow the number who are flagged for follow-up examina- tions but never develop the condi- tion. One method that could provide this greater precision is an algorithm of postnatal weight development as well as insulin-like growth factor I, called WINROP (weight, insulin-like growth factor I, neonatal, retinopa- thy of prematurity [ROP]). A study of WINROP's efficacy in a Brazilian infant population was published in the November 2010 issue of Archives of Ophthalmology. The study applied WINROP to in- fants in the neonatal intensive care unit of a Brazilian hospital from April 2002 to October 2008. Among this population of 366 infants, WINROP found little or no risk for the condition in 192 infants (52%), and only two of these infants devel- oped proliferative disease. The remaining 174 children (47%) re- ceived high- or low-risk alarms be- fore or at 32 weeks from conception, including 21 (12%) who ultimately developed proliferative ROP. Anna-Lena Hard, M.D., Ph.D., lead author of the study, and her colleagues touted WINROP's efficacy in detecting 91% of infants who de- veloped stage 3 ROP as well as pre- dicting the majority who did not, despite having limited information about the infants' specific gesta- tional age and date of weight meas- urements. "Adjustments to the algorithm for specific neonatal intensive care unit populations may improve the results for specific preterm popula- tions," wrote Dr. Hard and her col- leagues. However, the lack of precision indicated to Graham E. Quinn, M.D., professor of ophthalmology, University of Pennsylvania, and at- tending physician, division of oph- thalmology, the Children's Hospital of Philadelphia, that WINROP is still "in the development stage, and clearly not ready for clinical applica- tion without much more study." Improved precision may come from further refinement of the model, Dr. Quinn said, or other ana- lytic approaches using information about weight gain after birth could provide better results. "One must ask whether a sensi- tivity of 90% is acceptable for detec- tion of a potentially blinding disease," Dr. Quinn said. The study findings left contin- ued uncertainty over how WINROP should be used, according to Richard A. Saunders, M.D., N. Edgar Miles Professor of Ophthal- mology and professor of pediatrics, Storm Eye Institute, Medical Univer- sity of South Carolina, Charleston. It's possible that general ophthal- mologists or pediatric specialists could use it as an "adjunctive method of assessing risk, but not as a screening substitute." "At least in developed countries, the WINROP algorithm would seem to have an application as a clinical adjunct in determining how closely to follow high- and low-risk in- fants," Dr. Saunders said. "However, in other parts of the world, where broad-based ophthalmologic screen- ing is not feasible, screening only the high-risk subset of infants is cer- tainly defensible." The WINROP approach at- tempts to move beyond the most commonly used predictive tool for ROP: the baby's birth weight and gestational age, with most developed countries establishing limits below which repeated eye examinations of the baby are recommended, noted Dr. Quinn. It also differs from a more com- plex predictive tool used in the Early Treatment for Retinopathy of Prema- turity Cooperative Group (ETROP), published in 2003 in Archives of Oph- thalmology, which was based on ges- tational age, birth weight, time of onset of retinopathy, rapidity of dis- ease, and other factors. That algorithm stemmed from data gleaned by the Cryotherapy for Retinopathy of Prematurity Cooper- ative Group, also published in 2003 in Archives of Ophthalmology, which was a risk analysis of pre-threshold ROP among 4,000 children who had a history of ROP. "The appeal of such programs, including the WINROP program, is that it takes us beyond the classic risk factors of birth weight and ges- tational age to some indication of the postnatal course of the at-risk baby," Dr. Quinn said. "The re- searchers who have developed WINROP have done important ground-breaking work in the rela- tion between growth (as a surrogate for IGF) and ROP." The need for approaches like WINROP is likely to grow as more general ophthalmologists could be called on to conduct ROP examina- tions. Such predictive tools could de- crease the number of examinations that are needed, Dr. Quinn noted. In order to increase the reliabil- ity of WINROP, Dr. Quinn said more research is needed on larger samples of patients (more than a few hun- dred) in the United States and other countries. He especially urged cau- tion in the use of WINROP in devel- oping countries where little is known about the incidence and time course of ROP among prema- ture children. "I am concerned that applying this system without regard to the population will lead us to assume prematurely the system doesn't work, without recognizing its value in an appropriate population," Dr. Quinn said. "Improving neonatal care in these nurseries is the essen- tial task at this point, and I would be concerned if we started omitting ex- aminations in at-risk babies based on an algorithm developed on an- other patient population." EW Editors' note: Dr. Hard owns shares in a company controlling PremaCure AB, which has rights to WINROP. Drs. Quinn and Saunders have no financial interests related to their comments. Contact information Quinn: 215-590-4594, quinn@email.chop.edu Saunders: 843-792-5799, saundric@musc.edu February 2011 RETINA October 2011 A pediatric ophthalmologist examines an infant for signs of ROP Source: National Eye Institute, National Institutes of Health EyeWorld factoid The retina is thinnest at the foveal floor and thickest at the foveal rim Source: U.S. National Library of Medicine, National Institutes of Health 68-75 Feature 2 AMD_EW October 2011-DL2_Layout 1 9/29/11 3:48 PM Page 70

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