Comparison between weight gain and Fenton preterm growth z scores in assessing the risk of retinopathy of prematurity.

Several studies have shown that postnatal weight gain is a significant predictor for retinopathy of prematurity (ROP) in preterm infants. Using a cohort of 1,301 infants from a single-center ROP registry, we investigated whether incorporation of changes in Fenton preterm growth curve z scores (ie, deviation from the population average) provides improved predictive ability for developing ROP compared to weight gain alone. Three logistic regressions were fit to severe ROP: (1) baseline model that included gestational age and birth weight, (2) the baseline model adding weight gain, and (3) the baseline model adding change in z score. The area under the receiver operating characteristic curve (C index) was used to compare models. Both weight gain and change in z scores were significant predictors after adjusting for birth weight (P = 0.01) and gestational age (P < 0.01). The C indices were not significantly improved by including weight gain or z score to the baseline model; however, for a subset of subjects, change in weight z score may be a more useful measure compared to simple weight gain with regards to assessing risk for severe ROP.

The relationship of the subtypes of preterm birth with retinopathy of prematurity.

BACKGROUND: Retinopathy of prematurity is an adverse outcome of preterm birth and is a leading cause of childhood blindness. The relationship between the subtypes of preterm birth with retinopathy of prematurity is understudied. OBJECTIVE: To investigate whether there is a difference in the incidence of type 1 or type 2 retinopathy of prematurity in infants with preterm birth resulting from spontaneous preterm labor, a medical indication of preterm birth, or preterm premature rupture of the membranes. STUDY DESIGN: A retrospective cohort study was conducted of 827 infants screened for retinopathy of prematurity who were delivered at a single tertiary care center in Colorado. All infants fulfilled the American Academy of Pediatrics 2013 screening criteria for retinopathy of prematurity defined as "infants with a birth weight of ≤1500 g or gestational age of 30 weeks or less (as defined by the attending neonatologist) and selected infants with a birth weight between 1500 and 2000 g or gestational age of >30 weeks with an unstable clinical course, including those requiring cardiorespiratory support and who are believed by their attending pediatrician or neonatologist to be at high risk for retinopathy of prematurity." Two independent reviewers masked to retinopathy of prematurity outcomes determined whether preterm birth resulted from spontaneous preterm labor, medical indication of preterm birth, or preterm premature rupture of the membranes. Discrepancies were resolved by a third reviewer. Data were analyzed with univariate and multivariable logistic regression. RESULTS: In our cohort, the frequency of preterm birth resulting from spontaneous preterm labor, medical indication of preterm birth, or preterm premature rupture of the membranes was 34%, 40%, and 26%, respectively. The mean gestational age (weeks, days) ± SD (range) in the cohort and across the preterm birth subtypes was as follows: entire cohort, 28 weeks, 6 days ± 2 weeks, 3 days (23 weeks, 3 days - 36 weeks, 4 days); spontaneous preterm labor, 28 weeks 1 day ± 2 weeks, 3 days (23 weeks, 3 days - 33 weeks, 4 days); medical indication of preterm birth, 29 weeks, 1 day ± 2 weeks, 2 days (24-36 weeks, 4 days); preterm premature rupture of the membranes, 28 weeks, 4 days ± 2 weeks, 1 day (24-33 weeks, 1 day). Among infants with type 1, type 2, or no retinopathy of prematurity, the incidence of type 1 or type 2 retinopathy of prematurity in births from spontaneous preterm labor, medical indication of preterm birth, and preterm premature rupture of the membranes was 37 of 218 (17%), 27 of 272 (10%), and 10 of 164 (6%), respectively. Adjusted for gestational age, birth weight, and multiparity and compared with the preterm premature rupture of the membranes group, the odds ratios of spontaneous preterm labor and medical indication of preterm birth for type 1 or type 2 retinopathy of prematurity were 6.1 (95% confidence interval, 1.8 to 20, P = .003) and 5.5 (95% confidence interval, 1.4 to 21, P = .01), respectively. Among neonates born after preterm premature rupture of the membranes, the probability of developing type 1 or type 2 retinopathy of prematurity was greatest in infants with rupture of membrane duration of up to 24 hours. After 24 hours, the probability of developing type 1 or type 2 retinopathy of prematurity declined. The odds of developing type 1 or type 2 retinopathy of prematurity was 9.0 (95% confidence interval 2.3 to 34, P = .002) in infants who had preterm premature rupture of the membranes ≤ 24 hours compared with infants who had preterm premature rupture of the membranes > 24 hours. CONCLUSION: Type 1 or type 2 retinopathy of prematurity are adverse ocular outcomes linked with not only lower gestational age and birth weight at delivery but also with events in the intrauterine environment that trigger a preterm birth. The reduced incidence of type 1 or type 2 retinopathy of prematurity in the preterm premature rupture of the membranes group compared with other causes of preterm birth may be related to the perinatal therapies associated with preterm premature rupture of the membranes (such as corticosteroids, antibiotics, maternal-fetal surveillance), which may have an inhibitory effect on the development of retinopathy of prematurity. We suggest that the physiologic events that predispose infants to type 1 or type 2 retinopathy of prematurity begin before delivery.

Validation of WINROP for detecting retinopathy of prematurity in a North American cohort of preterm infants.

BACKGROUND: WINROP (weight, insulin-like growth factor 1, neonatal, retinopathy of prematurity) is a web-based retinopathy of prematurity (ROP) risk algorithm that uses postnatal weight gain as a surrogate of insulin-like growth factor-1 (IGF-1) to predict the risk of severe ROP in premature infants. The purpose of this study was to validate the web-based algorithm WINROP in detecting severe (type 1 or type 2) ROP in a North American cohort of infants. METHODS: The records of consecutive infants who underwent ROP examinations between 2008 and 2011 were reviewed retrospectively. Infants were classified into categories of "alarm" (at risk for developing severe ROP) and "no alarm" (minimal risk for severe ROP). RESULTS: A total of 483 were included. Alarm occurred in 241 neonates (50%), with the median time from birth to alarm of 2 weeks. WINROP had a sensitivity of 81.8% (95% CI, 67.3%-91.8%) and specificity of 53.3% (95% CI, 48.5%-58.0%) for identifying infants with severe ROP. Eight of the 44 infants with severe ROP were not detected (5 with type 1 and 3 with type 2). Of these 8 infants, 7 (88%) had birth weight in excess of the 70th pecentile. With additional weight data entry, sensitivity of WINROP rose to 88.6%. CONCLUSIONS: Very preterm infants (gestational age of ≤27 weeks) with relatively high birth weight for gestational age may not be detected by WINROP as high risk for developing severe ROP.

Real-time measurement of needle forces and acute pressure changes during intravitreal injections.

BACKGROUND: The purpose of this study was to use a physiological pressure transducer to measure real-time, continuous pressure changes in an ex vivo study model of porcine eyes to record the amount of force needed for scleral penetration and to measure acute intraocular pressure rise during intravitreal injections. METHODS: A pressure transducer was inserted into the anterior chamber of 30 fresh porcine eyes, and intraocular pressure was measured 2 s prior to intravitreal injection until 2 s after. A force transducer plate was used to insert various gauge needles into the vitreous cavity and the amount of force in Newtons (N) required for scleral penetration was recorded. RESULTS: For scleral perforation, 32- and 30-gauge needles required 0.44 N and 0.45 N, significantly less than larger gauge needles (P < 0.05). Similarly, 27- and 25-gauge needles required more force than smaller gauge needles but less than 19 gauge (P < 0.05). Intraocular pressure increased an average of 64.5 mmHg during intravitreal injection. Two seconds postinjection intraocular pressure readings showed a residual intraocular pressure increase of 11.1 mmHg from pre-injection baseline. CONCLUSION: Real-time continuous recordings of pressure reveal that an instantaneous intraocular pressure spike occurs during intravitreal injection and appears to be separate from the intraocular pressure spike that occurs during needle insertion. This pressure spike is transient and has not been captured by previous methods of intraocular pressure measurement, which rely on single time point measurements. The clinical significance of this brief intraocular pressure spike is unclear and warrants further investigation.

Colorado retinopathy of prematurity model: a multi-institutional validation study.

PURPOSE: The Colorado retinopathy of prematurity (ROP) prediction model (CO-ROP), developed using a cohort of infants from Colorado, calls for ROP examination of infants meeting all of the following criteria: gestational age of ≤30 weeks, birth weight of ≤1500 g, and a net weight gain of ≤650 g between birth and 4 weeks of age. The purpose of this study was to perform an external validation to assess the sensitivity and specificity of the CO-ROP model in a larger cohort of babies screened for ROP from four academic institutions in the United States. METHODS: The medical records of neonates screened for ROP according current national guidelines was conducted at 4 US academic centers were retrospectively reviewed. Sensitivity, specificity, and respective 95% confidence intervals in detecting ROP using CO-ROP were calculated for type 1, type 2, and any grade of ROP. RESULTS: A total of 858 cases were included. The CO-ROP algorithm had a sensitivity of 98.1% (95% CI, 93.3%-99.8%) for type 1 ROP, 95.6% (95% CI 78.0-99.9%) for type 2 ROP, and 95.0% (95% CI, 93.1-97.4%) for all grades of ROP. The CO-ROP model would have reduced the total number of infants screened by 23.9% compared to current 2013 screening guidelines. CONCLUSIONS: CO-ROP demonstrated high sensitivity in predicting ROP and would have greatly reduced the number of infants needing examination.

The Colorado-retinopathy of prematurity model (CO-ROP): postnatal weight gain screening algorithm.

PURPOSE: To describe a novel retinopathy of prematurity (ROP) screening model incorporating birth weight, gestational age, and postnatal weight gain that maintains sensitivity but improves specificity in detecting all grades of ROP compared to current 2013 screening guidelines. METHODS: The medical records of 499 neonates from a single tertiary referral center who met the 2013 screening guidelines for ROP were retrospectively reviewed. Weekly weights were analyzed using standard logistic regression to determine the age at which the weekly net weight gain best predicted the development of ROP, which was designated as the postnatal weight gain criterion. The 2013 birth weight and gestational age criteria were included in an "and" fashion to form the CO-ROP model. Sensitivities and specificities in detecting high grade (type 1 and 2) and all grades of ROP were calculated. RESULTS: The CO-ROP model screens infants with a gestational age at birth of ≤30 weeks and birth weight of ≤1500 g and net weight gain of ≤650 g between birth and 1 month of age. In our cohort, CO-ROP had a sensitivity of 100% (95% CI, 92.1%-100.0%) for high-grade (type 1 and 2) ROP and 96.4% (95% CI, 92.3%-98.7%) for all grades of ROP. It would reduce the number of infants screened by 23.7% compared to 2013 guidelines. Calibrating the model to detect only high-grade ROP would result in a 45.9% reduction in the total number of infants screened. CONCLUSIONS: CO-ROP is a simple model that maintains a statistically similar sensitivity in detecting all grades of ROP while significantly reducing the total number of required ROP screenings compared to 2013 guidelines. The study had a small sample size but shows promise for future research and clinical efforts.