Studies suggest that ROP is emerging as a major cause of treatable childhood blindness in middle income countries like China and in many other countries such as those in Latin America, Asia, and Eastern Europe.
3,10 At the beginning of this century, ROP screenings in China were available only in NICUs in developed cities such as Beijing, Shanghai, and Guangzhou. Since the initiation of the ROP screening program by the Ministry of Health of China in 2004, an increasing number of ROP studies were conducted, reporting on the incidence, characteristics, and treatment options of ROP (
Table 5). However, most of these results were published in Chinese journals.
12–24 Despite the differences in screening criteria, neonatal treatment, and the use of supplemental oxygen in different NICUs, these data present a clear picture that (1) in developed regions such as Beijing, Shanghai, and Guangdong Province, the rate of ROP was much lower than that in the less developed regions such as Henan Province and Qinghai Province, and (2) the incidence of ROP in China declined from 2000 to 2012, particularly in developed regions after 2004. These changes are most probably associated with the significant improvements in child healthcare in China, including prenatal care, delivery care, and postnatal care, as well as improved general socioeconomic conditions, such as increased household income, educational levels, and government initiatives.
25,26
The percentage of ROP and severe ROP observed in our study is comparable with the results obtained from other middle income countries.
27–29 In 2004, Trinavarat et al.
27 reported that the incidence of ROP in Thailand was 13.6% and 6.4% of screened infants developed severe ROP. In 2006, a prospective study conducted in South Africa also showed that ROP was diagnosed in 16.3% infants, and an estimated frequency of severe ROP was more likely to be 2.9%.
28 In 2010, Zin et al.
29 reported a study, including seven neonatal units in Rio de Janeiro found that the incidence of ROP was 16.9% and 3.6% of screened infants needed treatment. The characteristics of infants developing severe ROP and the incidences of treatable ROP vary from developed countries to middle income countries, possibly due to the combined differences in neonatal care, different screening criteria, economic conditions, races, and other risk factors. Compared with data from developed countries, such as the US and Canada,
30,31 the infants who developed severe ROP were bigger and more mature in our study. The quality of neonatal care may be highly relevant to the higher incidence of severe disease in larger infants in China. Similar results have been reported from other middle income countries in Asia and Latin America, such as India and Brazil.
29,32 In developed countries, the development of severe ROP is extremely rare in infants with BW of 1250 g or greater or GA of 31 weeks or greater.
2 With advanced economies and developed neonatal care, only 14.8% (209/1408) and 14.2% (24/169) of extremely low BW infants in the NICUs in the US
33 and Canada
31 were treated.
The higher mean GA and BW in our study reflect the relatively high mortality rate among extremely premature infants in China. For example, in our study only 8 of 415 (1.9%) infants with BW less than 1251 g had BWs of less than 750 g, which contrasts with 26.1% in ETROP.
30 Meanwhile, the proportion of babies GA less or equal to 27 weeks was 20.7% (86/415), also lower than the 47.2% (3305/6998) observed in ETROP.
30 A portion of infants in our initial study died before or during our screening, among which 110 infants were less than 1000 g in BW. Such a relatively high mortality rate in extremely preterm infants in Chinese NICUs was likely reflecting a combined effect of lack of high-quality neonatal care compared with developed countries, and the balance between the costs of care and the family's ability to afford the care.
The reported incidence of ROP varies between countries and even between regions and units, suggesting that caution must be applied in extrapolating conclusions about ROP screening criteria from one population to another. The findings of our study have important implications that, even in tertiary care NICUs in urban areas of China, more mature infants are at risk of developing severe ROP. If the UK or US guidelines had been applied to our subject population, many infants would have missed the opportunity for treatment. This discrepancy is likely due to differences in systems of neonatal healthcare and the population studied. Therefore, the ROP screening criteria in China needs to be wider than the developed countries. However, medical care for neonates in China has improved dramatically over the past decade, as evidenced by the increased survival rate of low BW infants,
34,35 resulting in more infants eligible for ROP screening, which greatly increases the workload of Chinese ophthalmologists.
The objective of ROP screening is to identify all infants who require treatment. The minimum number of infants to be screened without missing any case of concern would constitute an effective guideline. There is a potential for lessening workload by reducing the upper inclusion limits of BW and GA. In our present study, if we used the criteria we recommended, GA less than or equal to 33 weeks and/or BW less than or equal to 1750 g, nearly 500 infants would not have needed examinations. That would reduce the workload by almost 20%, which is especially relevant to China where the population to be screened is large, but screening facilities and ROP expertise are limited. Our results are encouraging for us to modify the current ROP screening protocol, but may not be applicable to other regions in China due to differences in neonatal care and other relevant factors.
Our study has inherent shortfalls, as it was conducted in the NICUs in Shanghai, a major metropolitan city in China, so the incidence and severity of ROP are not representative of those in the entire Chinese population. Further population-based studies on premature infants in the broader community are essential so that the incidence and severity of ROP in China may be assessed comprehensively and definitively.