Retinopathy of Prematurity Outcome in Infants With Prethreshold Retinopathy of Prematurity and Oxygen Saturation >94% in Room Air: The High Oxygen Percentage in Retinopathy of Prematurity Study

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 ≤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.

W.V. Good as co-investigator