Abstract
Purpose: :
To investigate the relationship between the gestational age (GA) of onset of retinopathy of prematurity (ROP) and its natural history. The effects of two different neonatal oxygen saturation protocols on this relationship are also examined.
Methods: :
A retrospective chart review was conducted for all eligible inborn infants screened for ROP the two years immediately prior to (Group 1), and the two years following (Group 2), the institution of a new oxygen protocol, which adjusted target oxygen saturation from 90-99% to 85-93%. Early- versus late-onset ROP was defined as disease present on examination at <36 versus ≥36 weeks’ GA, respectively. Additional charts for all inborn infants treated for ROP in years 3 and 4 subsequent to the oxygen protocol change were also reviewed. Early Treatment for Retinopathy of Prematurity treatment guidelines were followed throughout the entire study period.
Results: :
The median birth weight/GA of infants with early-onset ROP was 840g/26.14 weeks, versus 952.5g/28 weeks with late-onset ROP (p=0.0003/p<0.0001). ROP developed in 117/387 (30.2%) infants in Group 1, and 96/386 (24.9%) infants in Group 2. Cumulatively, 35/144 (24.3%) of early- and 8/69 (11.6%) of late-onset patients required treatment (p=0.031). Maximal severity of disease after treatment, including frequency of retinal detachment, was similar in early- and late-onset patients, independent of the oxygen protocol used (p=1.00). Concordance (identical stage of severity in each eye) of disease was unaffected by the change in oxygen protocol (74% versus 69%, p=0.68).
Conclusions: :
Onset of ROP at a GA ≥36 weeks was associated with an increased birth weight and a decreased likelihood of requiring treatment, although approximately 10% of patients with late-onset ROP did undergo treatment for high risk disease. However, the final post-treatment outcomes were similar in children with early- versus late-onset disease. Irrespective of age of onset of disease, specific oxygen protocol use was unrelated to the development of ROP and need for treatment, and had no effect on concordance of disease between eyes. Clinicians should remain diligent in ROP examinations beyond 36 weeks’ GA, regardless of the oxygen protocol in use, as high risk ROP may still develop after this time.
Keywords: retinopathy of prematurity • oxygen