Is a new epidemic of retinopathy of prematurity under way? It depends on where you live. Sadly, it also depends on how long your children live.
The worldwide incidence of ROP varies dramatically by country, driven in part by the varying availability and quality of neonatal care and treatment. In the wealthiest countries, the overall incidence of ROP appears to be holding steady, despite an increase in premature births. And in the poorest countries, ROP isn’t a significant issue, only because premature infants typically do not survive long enough to develop the condition.
But the situation is significantly different in the vast “middle” of the economic spectrum. “It’s fair to say that there’s an epidemic in the developing world,” said Michael X. Repka, MD, professor of ophthalmology and pediatrics at Johns Hopkins University.
Countries hit the hardest include many in Latin America and the former Eastern European bloc. For instance, in the Czech Republic, ROP accounts for 41.9 percent of cases of blindness in children. Comparable figures are 60 percent for Argentina, 38.6 percent for Cuba and 33.3 percent for Paraguay. (In contrast, the figures for the United States, Sweden and the United Kingdom are 13, 4 and 3 percent,
Potential reasons for this epidemic include increases in the overall birth rate and in the number of premature births. In addition, the provision of maternal and neonatal care is uneven in many countries, as is ROP screening and treatment. “Unfortunately, we can’t export all aspects of neonatal care,” Dr. Repka said. “As these countries save more babies, they’re also seeing more of the complications of prematurity.”
|Birth weight and gestational age as predictors of ROP may vary among countries. |
In the United States and other highly developed countries, ROP is being diagnosed in ever-smaller infants. A worldwide analysis of the characteristics of infants with severe ROP found that the mean birth weight (BW) of infants from highly developed countries ranged from 737 to 763 grams, and the mean gestational age (GA) for these babies ranged from 25.3 to 25.6 weeks.1
A recent report from the Institute of Medicine noted an uptick in the number of preterm deliveries in the United States, thanks in large part to the confluence of assisted fertility techniques and older maternal age.2 However, it is unclear whether this will necessarily translate into an increase in ROP cases. “I’m not aware of prevalence studies that would suggest an increase in ROP. The overall feeling in the community is that some physicians think the rate is about the same—it’s just that we’re seeing it in smaller infants, while the larger babies are being spared. We essentially have a shifting of the at-risk population to smaller birth weights,” Dr. Repka said.
I look robust? Look at my retina. Elsewhere in the world, paradoxically, “There is an increasing realization that bigger, more mature babies are getting ROP and needing treatment in middle-income countries and cities in Asia,” said Clare E. Gilbert, MD, MSc, acting head of the International Centre for Eye Health at the London School of Hygiene and Tropical Medicine.
ROP in this context of larger BW and GA is not well-elucidated, but it means that some of these infants would be missed by the screening criteria used in the United States and the United Kingdom.
The U.S. criteria recommend screening for infants with a BW of < 1,500 g or a GA
of < 32 weeks. But Dr. Gilbert’s team found that the BW of infants with ROP in less-developed countries ranged from 903 to 1,527 g and the GA ranged from 26.3 to 33.5 weeks. Granted, the U.S. screening is extended to BWs of 2,000 g and GAs of > 32 weeks in babies who also have an unstable clinical course.3 But that still means the criteria would miss stable premature infants in some countries. For instance:
- In China, a review of 114 babies with ROP found that their mean GA was 29.8 weeks and the mean BW was 1,432 g. But for 31 of the infants, the BW was > 1,500 g; for 10, the GA was > 32 weeks. Overall, 18 of the infants exceeded the screening criteria used in the United Kingdom and 34 exceeded the criteria used in the United States.4
- In southern India, a study of 120 infants with ROP found that the mean GA was 29.6 weeks, with a range of 26 to 36 weeks. The mean BW was 1,254 g, with a range of 710 to 2,000 g. Moving the screening criteria up to a GA of 34 weeks and a BW of 1,750 g would have covered all but one of the infants, the researchers note.5
In the United States, a recently revised Joint Policy Statement on screening3 acknowledges this issue, noting that it is “important to recognize that other world locations could have very different screening parameters.”
Some countries have taken steps to develop their own criteria. For instance, in Ecuador, the screening criteria were changed to a BW of < 1,901 g and a GA of < 37 weeks. Adoption of the more inclusive criteria has led to a decrease in ROP-related blindness.1
Dr. Gilbert added, “I am working with a Brazilian ophthalmologist at the moment. She is screening on five units in Rio de Janeiro and collecting data from two other units. One of the questions is whether screening criteria need to vary depending on neonatal outcomes or the quality of the care in the neonatal ICUs. This study will not be finished until the end of the year, so no results yet.”
While Ecuador’s experience argues in favor of modifying screening criteria to include larger and more mature infants, doing so is likely to place additional financial burdens on the health care systems of many countries.
Digital baby pictures. One potential solution may lie in telemedicine, with retinal photographs serving as a substitute for serial clinical exams. In countries where there is a shortage of trained examiners, telemedicine may prove to be a viable alternative. “Low manpower, high demand and high stakes—a lifetime of blindness—add up to a ‘perfect storm’ for a telemedicine approach to ROP evaluation,” said Anna L. Ells, MD, a pediatric ophthalmologist and retina specialist at the Alberta Children’s Hospital in Calgary, Canada.
“There are short-term challenges in equipment size, portability and costs,” said Dr. Ells. But overall, she added, “I am optimistic that a telemedicine approach to ROP evaluation will improve the delivery of care.” However, she said, “The integration of Web-based networks, standardized image acquisition, centralized reading protocols and effectiveness of a wide implementation still need to be evaluated. The feasibility and validation of a large, wide-area scalable system still needs to be done.”
And Dr. Gilbert provided a reality check for this Internet age: In developing countries, she noted, “Mothers often do not have telephones, which might cause a problem for babies who need evaluation but who have been discharged.”
Although ROP is not at epidemic levels in the developed world, the current liability situation can be described as an unfolding crisis.
In the United States, “for those who have been involved with litigation, this is a terribly frustrating issue,” said Dr. Repka.
“The reputation of the disease is such that no one wants to touch it.” Indeed, a growing number of ophthalmologists are opting out of caring for patients with ROP (see “News in Review,” page 17, July/August EyeNet).
Hope for these kids is not just academic. Currently, much of the care provided to infants and children with ROP “is being done in academic medical centers via faculty physicians, residents and fellows,” Dr. Repka said. “Even so, it can be difficult to get people involved.”
The real problem, Dr. Repka said, comes with “back transport to the community nurseries and to hospitals with small neonatal ICUs.”
“These facilities are seeing just a handful of kids, and the exams are poorly reimbursed, so follow-up care is difficult to obtain.”
It is, as he acknowledged, “a systems issue,” and one that is unlikely to be easily or quickly solved. As a partial solution, a number of different contractual relationships are being explored, he said.
“The leading solution seems to be participation by the hospital to help provide some financial and liability coverage to the ophthalmologist. Of course, this may not solve the liability issue in court.”
Drs. Ells, Gilbert and Repka have no related financial interests.
1 Gilbert, C. et al. Pediatrics 2005;115:e518–525.
2 Preterm Birth: Causes, Consequences and Prevention. To order, see www.iom.edu.
3 Joint Policy Statement. Pediatrics 2006;117:572–576.
4 Chen, Y. and X. Li. Br J Ophthalmol 2006;90:268–271.
5 Jalali, S. et al. Am J Ophthalmology 2006;141:966–968.