The Photographic Screening for Retinopathy of Prematurity Study (Photo-ROP): study design and baseline characteristics of enrolled patients.
OBJECTIVE: The Photographic Screening for Retinopathy of Prematurity Study (Photo-ROP) sought to evaluate the utility of digital wide-angle photographic fundus screening for retinopathy of prematurity (ROP) as compared to bedside indirect ophthalmoscopy. This article describes the study design and presents baseline characteristics of the subjects. DESIGN: Prospective, multicenter, masked, Internet-based clinical trial. PARTICIPANTS: Premature infants <31 weeks postmenstrual age at birth and <1000 g birthweight. INTERVENTIONS: Examinations began at 31 weeks postmenstrual age or 4 weeks postnatal age, whichever was later. Both eyes of all infants were imaged with a panoramic fundus imaging system followed by indirect ophthalmoscopic fundus examination. Images were transmitted via Internet to the Reading Center for interpretation by masked graders. Clinical interpretations based on indirect ophthalmoscopy were recorded for comparison with the Reading Center determinations. Examinations were performed weekly for 10 weeks or until an infant was discharged from the hospital. MAIN OUTCOME MEASURE: Sensitivity, specificity, and positive and negative predictive values of Reading Center image interpretations were compared to clinical impressions based on bedside indirect ophthalmoscopy. RESULTS: Enrollment began in February 2001 and was completed in February 2002. The target number of infants was 50, and 62 were enrolled. Of those enrolled, 51 infants (102 eyes) were considered eligible, and are the subject of this article. Mean postmenstrual age (+/- SD) at time of delivery was 26.80 +/- 1.73 weeks (median = 26.86 weeks, interquartile range [IQR] = 2.43 weeks). Mean postmenstrual age at first examination (+/- SD) was 32.19 +/- 2.86 weeks (median = 31.71 weeks, IQR = 2.29 weeks). Mean birthweight (+/- SD) was 830.51 +/- 219.57 g (median = 817 g, IQR = 225 g). Female infants comprised 49.02% of the patients. Race distribution was as follows: white 45.10%, African or black 39.22%, Hispanic 3.92%, Asian 9.80%, and other races 1.96%. Mean follow-up (+/- SD) was 5.73 +/- 3.22 weeks (median = 6 weeks, IQR = 5, range = [1, 15]). CONCLUSIONS: The Photo-ROP Study Cooperative Group successfully recruited and enrolled at-risk premature infants into a longitudinal, prospective clinical trial comparing two different diagnostic approaches. Technology employed in this study is comparable to that currently available. Design issues for this trial included establishing the information technology infrastructure for an ROP study based on digital imaging, defining the study endpoints, estimating event rates, defining a standardized imaging protocol, and defining standards for interpretation of image quality and clinical findings.