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Incidence of severe retinopathy of prematurity before and after a modest reduction in target oxygen saturation levels

Presented at the 32nd Annual Meeting of the American Association for Pediatric Ophthalmology and Strabismus, Keystone, Colorado, March 15-19, 2006.
https://doi.org/10.1016/j.jaapos.2006.08.012Get rights and content

Background

Previous studies suggest that reducing target oxygen saturation levels to 85–93% decreases the incidence of severe retinopathy of prematurity (ROP). Our aim was to determine if a more modest reduction in target oxygen saturation levels also reduces ROP incidence.

Methods

One neonatal intensive care unit instituted new oxygen saturation guidelines that changed target levels from the upper 90s to 90–96%. We conducted a retrospective cohort study to determine the proportion of eyes that progressed to (1) threshold or type-1 ROP and (2) stage 3. These proportions were compared between two groups of all eligible infants born up to 10 months before (higher oxygen group, n = 46) and up to 16 months after (lower oxygen group, n = 59) the policy change. Binomial regression was used to calculate relative risks adjusted for birth weight, gestational age, apnea, days of mechanical ventilation, and length of hospital stay.

Results

Sixteen of 90 eyes (18%) in the higher oxygen group developed threshold or type-1 ROP versus 16 of 118 eyes (14%) in the lower oxygen group (adjusted relative risk = 0.66, 95% CI = 0.29, 1.51). Twenty-two of 88 eyes (25%) in the higher oxygen group developed stage 3 ROP versus 26 of 118 eyes (22%) in the lower oxygen group (adjusted relative risk = 0.76, 95% CI = 0.43, 1.37).

Conclusions

We observed a small but statistically insignificant reduction in the incidence of severe ROP after a modest reduction in target oxygen saturation levels to 90 to 96% in the first several weeks of life.

Section snippets

Subjects and Methods

We used a retrospective cohort study design. Eligibility criteria were as follows: (1) birth weigh less or equal than 1250 g; (2) no more than 1 week (7 days) of the first 6 weeks of life spent at another hospital; and (3) serial ROP examinations performed for a period of time sufficient to determine if the outcome measures were present or absent (primary outcome = threshold or type-1 ROP7; secondary outcome = stage 3). These outcomes were considered to be absent if they had not appeared by an

Study Population

One hundred ten eyes of 55 infants in the higher oxygen group and 162 eyes of 81 infants in the lower oxygen group had a birth weigh less or equal than 1250 g and spent no more than one of the first 6 weeks of life at another hospital. Of these, 90 eyes of 46 infants in the higher oxygen group and 118 eyes of 59 infants in the lower oxygen group had an outcome determined and were included in the primary analyses. In the higher oxygen group, 20 of 110 eyes (18%) in 11 patients were excluded

Discussion

We used a retrospective cohort design to investigate whether a modest reduction in target oxygen saturation levels reduced the incidence of ROP in one nursery. After adjustment, our relative risk point estimates suggested a modestly protective effect of lower oxygen target saturation levels on the development of severe ROP. However, this single-center study had a limited sample size. Therefore, these estimates were imprecise and not statistically significant.

Other studies have reported

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This work was supported by a K23 Grant from the National Eye Institute (K23 EY015806).

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Copyright © 2007 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.