Higher mortality among unscreened children

Jan 19 2009

Swedish researchers have previously shown that as maternity ward stays become shorter, more and more newborns leave the hospital with undetected life-threatening congenital heart disease.

A study performed by researchers at the Sahlgrenska Academy shows that routine screening of the oxygen level in the blood of all newborns increases the detection of life-threatening heart malformations, which results in fewer infants dying and a likely lower risk of life-long brain damage.

One to two children per 1,000 babies are born with a so-called ductus-dependent heart disease. These heart malformations are directly life-threatening in that the flow of blood to the lungs or the rest of the body is shut off when the ductus arteriosus, a blood vessel that is open during the foetal period, gradually closes after birth. When only conventional paediatric examinations are carried out at maternity wards before discharge, many of these heart malformations are missed, since they often lack a detectable heart murmur. About 30 percent of children with ductus-dependent heart disease therefore leave the maternity ward undiagnosed, which means that they fall ill at home, often with severe complications such as circulatory collapse and resulting organ failure.

“One out of six children that suffer circulatory collapse or organ failure at home do not make it to the hospital in time and die. But if the heart disease is detected in time, the majority can be operated on with good results,” says Ingegerd Östman-Smith, professor of paediatric cardiology at the Sahlgrenska Academy and one of the researchers behind the study, which is now being published in the British Medical Journal.

Simple and quick test saves lives

Pulse oximetry screening is a quick and simple method for measuring the oxygen concentration in the child's blood. By placing a sensor on a hand, and in this study also on a foot, the concentration of oxygen is measured before the child leaves the hospital. If the oxygen concentration is lower than normal, it may indicate that the child has a heart problem and needs to be examined further. The screening is carried out by a midwife or a nursery nurse and takes about five minutes.

“The method is simple and reliable, and the fact that the infants are diagnosed to a greater extent before the heart disease has caused any damage that requires intensive care renders this method highly cost-effective,” says Ingegerd Östman-Smith.

Professor Ingegerd Östman-Smith and PhD-student Anne De-Wahl Granelli, together with colleagues, have assessed the efficacy of pulse oximetry screening in the Western Götaland region and compared with the proportion of ductus-dependent heart diseases detected in other regions and county councils that performed only conventional paediatric examinations before discharge. Nearly 40,000 infants were screened, all born in the Western Götaland region between July 1, 2004, and March 31, 2007,

The researchers found that among apparently healthy infants due for discharge 82.8 percent of all ductus-dependent heart diseases were discovered when the babies were examined both by a paediatrician and with the aid of pulse oximetry. When the children were only examined by a paediatrician, 62.5 percent of the heart diseases were detected. Some infants had been diagnosed before their discharge examination, so a total of 92 percent of children with ductus-dependent heart diseases were identified in the Western Götaland region during the period under study. This was significantly better than the regions compared, which only performed paediatric examinations, where 72 percent were detected.

“The risk of leaving the maternity ward with an undetected life-threatening heart disease was thus only 8 percent in Western Götaland, compared with 28 percent in the regions compared,” says Ingegerd Östman-Smith.

Higher mortality among unscreened children

The study shows that infants that left the maternity ward with undiagnosed heart disease had a much higher mortality rate than those who were diagnosed before discharge: 18 percent versus 0.9 percent when comparing children who were not premature or were lacking a functioning left ventricle. No children died at home with undiagnosed heart disease in the Western Götaland region during the study period, compared with five deaths at home in the regions under comparison.

The assessment of costs showed that screening is cost-neutral when introduced. All that is needed is a machine with a one-off outlay of about SEK 12,000 (~$1,500) per delivery unit as well as the time, roughly five minutes per infant, it takes for a nurse to perform the screening. Since the method would entail a probable decrease in neurological damage caused by circulatory collapse, and less need for pre-operative intensive care, this screening is likely to be cost-effective in the long term.

The prestigious British Medical Journal, which is publishing the study, is also including an editorial commentary by Professor Keith Barrington, Montreal, Canada. He points out that, on the basis of the evidence from this study, routine pulse oximetry screening is a low-risk and low-cost strategy to enhance the detection of critical congenital heart diseases, and that its “introduction should be seriously considered in all countries with access to pediatric heart surgery.”

The screening study constitutes a doctoral project for Anne De-Wahl Granelli, directed by the professor of paediatric cardiology, Ingegerd Östman-Smith, Department of Clinical Sciences, Sahlgrenska Academy, Gothenburg University, and Queen Silvia Hospital for Children and Adolescents.