ABSTRACT
BACKGROUND: Retinopathy of prematurity (ROP) is a vasoproliferative disease of the retina that occurs in premature infants. The prevalence of ROP reported so far is inconsistent. AIM: To conduct a systematic review to describe the trend of ROP prevalence between 1985 and 2021, and to determine the influence of countries' economic conditions on ROP prevalence. METHODS: We searched PubMed, Embase, and Google Scholar for studies published between January 1985 and December 2021 using the following MeSH terms: "retinopathy of prematurity", "ROP", "incidence", and "prevalence". Two independent reviewers examined the articles to select studies that met the selection criteria and performed data extraction and study quality assessment. For the meta-analysis, the pooled prevalence was calculated using a random-effects model and R software. RESULTS: Of 5,250 titles and abstracts, 139 original studies met the inclusion criteria; a total of 121,618 premature infants were included in these studies. The pooled prevalence of ROP was 31.9% (95% confidence interval [CI] 29.0-34.8) and that of severe ROP was 7.5% (6.5-8.7). In general, no significant differences in prevalence were found over the four decades; however, we found a higher prevalence in premature infants ≤28 weeks of gestational age. In addition, the highest ROP prevalence was found in lower-middle-income countries with high mortality rates. In contrast, the highest severe ROP prevalence was found in high-income countries. CONCLUSION: ROP remains a common cause of morbidity in premature infants worldwide. Therefore, it seems necessary to maintain early identification strategies for patients at higher risk, particularly in low- and middle-income countries.