Objectives: To determine the rate of progression from prethreshold to threshold retinopathy of prematurity (ROP) in infants excluded from Supplemental Therapeutic Oxygen for Prethreshold Retinopathy of Prematurity (STOP-ROP) because their median arterial oxygen saturation by pulse oximetry (SpO2) values were >94% in room air at the time of prethreshold diagnosis and to compare them with infants who were enrolled in STOP-ROP and had median SpO2 < or =94% in room air.
Methods: Fifteen of the 30 centers that participated in STOP-ROP elected to participate in the High Oxygen Percentage in Retinopathy of Prematurity study (HOPE-ROP) from January 1996 to March 1999. Infants were followed prospectively from the time prethreshold ROP was diagnosed until ROP either progressed to threshold in at least 1 study eye (adverse outcome) or resolved (favorable outcome).
Results: A total of 136 HOPE-ROP infants were compared with 229 STOP-ROP infants enrolled during the same time period from the same 15 hospitals. HOPE-ROP infants were of greater gestational age at birth (26.2 +/- 1.8 vs 25.2 +/- 1.4 weeks) and greater postmenstrual age at the time of prethreshold ROP diagnosis (36.7 +/- 2.5 vs 35.4 +/- 2.5 weeks). HOPE-ROP infants progressed to threshold ROP 25% of the time compared with 46% of STOP-ROP infants. After gestational age, race, postmenstrual age at prethreshold diagnosis, zone 1 disease, and plus disease at prethreshold diagnosis were controlled for, logistic regression analysis showed that HOPE-ROP infants progressed from prethreshold to threshold ROP less often than STOP-ROP infants (odds ratio: 0.607; 95% confidence interval: 0.359-1.026).
Conclusions: The mechanisms that result in better ROP outcome for HOPE-ROP versus STOP-ROP are not fully understood. It seems that an infant's SpO2 value at the time of prethreshold diagnosis is a prognostic indicator for which infants may progress to severe ROP. When other known prognostic indicators are factored in, the SpO2 is of borderline significance.