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Rachel E. Reem, Tessa Nguyen, Yinxi Yu, Gui-Shuang Ying, Lauren Tomlinson, Gil Binenbaum; Effects of Altitude on Retinopathy of Prematurity. Invest. Ophthalmol. Vis. Sci. 2020;61(7):2190.
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High altitude has many short and long term effects on the human body. Prematurity is a complex medical state that is sensitive to a host of external factors and produces unique disease processes, including retinopathy of prematurity (ROP). We sought to determine whether increasing altitude affects the incidence, onset, or severity of ROP.
Secondary analysis was performed using detailed ROP screening data on 11,463 infants from two North American Studies: G-ROP-1 (retrospective, 7483 infants from 29 hospitals, 2006-2012) and G-ROP-2 (prospective, 3980 infants from 41 hospitals, 2015-2017). Outcomes included rates and timing of onset of any ROP or severe (type 1, 2, or treated) ROP, stratified by hospital altitude and controlling for birth weight and gestational age in multivariable analysis.
Hospital elevation ranged from 13 to 5280 feet above sea level. Severe ROP developed in 1,434/11,463 (12.5%) infants. For every 500-ft elevation increase, there was a small but significant increase in the rate of any ROP (adjusted odds ratio (aOR) 1.04, 95% CI 1.02-1.06, p=0.001) and severe ROP (aOR 1.03 95% CI 1.00-1.06, p=0.03). The incidence of ROP was 42.1% at low (<1400 ft) and 48.3% at high (>4000 ft) altitude (p=0.44), and incidence of severe ROP was 12.2% at low altitude versus 17.2% at high altitude (p=0.01). Postmenstrual age (PMA) at development of any ROP did not significantly differ between low and high altitude (mean 35.7 and 35.8 weeks, respectively). However, each 500-ft increase in elevation was associated with +0.14 PMA weeks later development of severe ROP (95% CI 0.07-0.20, p<0.001). Severe ROP developed at mean PMA 37.9 weeks at high-altitude versus 36.9 weeks at low altitude.
Increasing altitude is associated with an increased risk of severe ROP. While the initial onset of ROP does not appear to be affected, increasing altitude results in delayed onset of severe ROP, by as much as a full week at highest altitudes.
This is a 2020 ARVO Annual Meeting abstract.
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