Filtered Sunlight is Safe and Noninferior to Phototherapy in Neonatal Hyperbilirubinemia Patients

A study in the New England Journal of Medicine suggests that the use of filtered sunlight for phototherapy is both safe and noninferior to conventional phototherapy for the treatment of neonatal hyperbilirubinemia. The finding is important, both because severe neonatal hyperbilirubinemia can lead to fatal complications, and because in some cases, existing guidelines for managing neonatal hyperbilirubinemia explicitly discourage the use of sunlight for the treatment of neonatal hyperbilirubinemia.

In high-income countries, hyperbilirubinemia is often easily diagnosed and treated with phototherapy. “However, in areas with limited resources, conventional phototherapy, defined as irradiance of at least 8 to 10 μW per square centimeter per nanometer, is often unavailable because of its cost or ineffective because of the inconsistent supply of electrical power or the low levels of irradiance emitted by the phototherapy bulbs available, which may be inferior in quality or limited in quantity or may have deteriorated,” the study authors noted.

Even for those infants who survive severe neonatal hyperbilirubinemia, the condition can progress to acute bilirubin encephalopathy or kernicterus, and infants may have severe long-term impairments, including choreoathetoid cerebral palsy, deafness, language-processing disorders, and general developmental delays.

The study was a randomized, controlled, noninferiority trial of 447 infants (224 assigned to filtered sunlight, and 223 to conventional phototherapy) in which filtered sunlight was compared with conventional phototherapy for the treatment of hyperbilirubinemia in term and late—preterm neonates in a large, urban Nigerian maternity hospital. The primary end point was efficacy, which was defined as a rate of increase in total serum bilirubin of less than 0.2 mg per deciliter per hour for infants up to 72 hours of age or a decrease in total serum bilirubin for infants older than 72 hours of age who received at least 5 hours of phototherapy. The authors prespecified a noninferiority margin of 10% for the difference in efficacy rates between groups. Safety was also measured, as defined by the absence of the need to withdraw therapy because of hyperthermia, hypothermia, dehydration, or sunburn.

Filtered sunlight was efficacious on 93% of treatment days that could be evaluated, as compared with 90% for conventional phototherapy, and had a higher mean level of irradiance (40 vs. 17 μW per square centimeter per nanometer, P<0.001). Temperatures higher than 38.0°C occurred in 5% of the infants receiving filtered sunlight and in 1% of those receiving conventional phototherapy (P<0.001), but no infant met the criteria for withdrawal from the study for reasons of safety or required an exchange transfusion.

Interestingly, total serum bilirubin fell more rapidly on treatment with filtered sunlight than with conventional phototherapy. With filtered sunlight, the median rate of change in bilirubin was −0.07 mg per deciliter per hour, and with conventional phototherapy, the median rate of change was 0.00 mg per deciliter per hour (P<0.001).

One concern about the use of filtered sunlight is that little is known about the longer-term toxicity associated with brief exposures to high-intensity, broad-spectrum visible light. The films used in the study to filter sunlight filtered out more than 99% of ultraviolet radiation. “The development of films whose filtering characteristics automatically adjust in response to the intensity of sunlight (similar to light-sensitive lenses in eyeglasses) could provide more consistent levels of irradiance,” the study authors note. “From a practical perspective, especially in a developing country such as Nigeria, the theoretical or unknown risks of brief exposures to high-intensity light must be weighed against the risk of death or severe disability associated with acute bilirubin encephalopathy and kernicterus.”

According to the researchers, “Advantages of filtered sunlight include its availability in remote locations, the provision of treatment at the safest and most efficacious wavelength, and, when a large canopy is used, the increased opportunity for maternal—infant bonding, for the provision of skin-to-skin care, and for the feeding of infants when they are hungry. The energy source is free, and the cost of the film is low.”