GENETICS

Is there a Clinical Benefit From
Neonatal Screening for CF?
By M.H. Cazes, G. Bellis, A. Nourry, E. Le Roux, S. Ravilly,
A. Munck, F. Huet, and C. Marguet

We report an interesting French research study, conducted between 1999 and 2003 by the Institut National d’Etudes Démographiques, that looked at a number of health outcomes in 564 six year old children with CF. Comparisons were made between:

• Neonatal Screening Group (NS): a group of 126 children from French regions who were diagnosed as a result of neonatal screening,
• Meconium Ileus Group (MI): a group of 103 children diagnosed through the presence of meconium ileus at birth,
• Clinical Diagnostic Group (CS): a group of 335 children diagnosed later based on clinical symptoms.

Variables measured at 6 years of age were height and weight, BMI (body mass index); forced expiratory volume (FEV1) and forced vital capacity (FVC); Staphylococcus and Pseudomonas aeruginosa colonization; number of outpatient visits, number of traditional hospitalizations, total number of “one day” admissions; use of intravenous antibiotic therapy, oxygen therapy, nebulised therapy, use of pancreatic enzyme, Total Parenteral Nutrition (TPN).#, enteral nutrition* and lung transplant.

In addition the evolution of Pseudomonas aeruginosa and Staphylococcus aureus colonization was recorded annually for each year for each of the three diagnostic groups.

The main findings were that Pseudomonas aeruginosa colonization was significantly less likely in the CF neonatal screening group, and more likely in the clinical diagnostic group. Nebulized therapy was therefore more commonly required in the clinically diagnosed group than the neonatal screening group. No difference was observed for any other parameters listed above and there was no difference in the prevalence of colonisation by Staphylococcus aureus.

Figure 1: Frequency of P. aeruginosa colonized patients according to age and diagnostic group (the three diagnostic groups are significantly different for the years 1, 3, 5, 6, and 7)

Most of the primary colonisations were diagnosed before the age of 3. The percentage of MI and CS colonized children increases later. Conversely, the percentage of NS children being ever colonized remained at a stable level from 15% to 20%. This result did not change when the children with a very early clinical diagnosis were considered in the analysis.

Research team at Institut National d’Etudes Démographiques, Paris, France

The main result of this study suggests that neonatal screening might delay the time when many children are colonised by P. aeruginosa. However, the causes of the delay observed in P. aeruginosa colonization could not definitely be determined. The CF French registry did not specify whether P. aeruginosa colonization might be identified as chronic or intermittent, both being included in the analysis. Conversely, neonatal screening did not appear to affect the proportion of children with S. aureus colonization at age 6.

No difference between the groups was found in FEV1 as previously reported (Farrell et al 2003) and growth at age 6 conversely to that observed by Farrell et al, 2001. In conclusion, this report suggests that neonatal screening had a favourable effect on the lower airway P. aeruginosa colonization in this large cohort study, but does not provide an explanation for this significant finding.

Editor’s Note
# Total Parenteral Nutrition (TPN) is used for patients who cannot or should not get their nutrition through eating. TPN will drip through a needle or catheter placed in your vein for 10-12 hours, once a day or five times a week. TPN may include a combination of sugar and carbohydrates (for energy), proteins (for muscle strength), lipids (fat), electrolytes, and trace elements. Your solution may contain all or some of these substances, depending on your condition.

* Enteral Nutrition is another way people can receive the food they need. Also called “tube feeding,” enteral nutrition is a mixture of all the needed nutrients. It is thicker than parenteral nutrition and sometimes it looks like a milk shake. It is given through a tube in the stomach or small intestine.

For a full report on this study write to the editor at editor@cfww.org

References
1. Farrell et al, 2003. Broncho-pulmonary disease in children with cystic fibrosis after early or delayed diagnosis, Am J Respir Crit Care Med, 2003 Nov 1;168(9):1100-8.

2. Farrell et al, 2001. Early diagnosis of cystic fibrosis through neonatal screening prevents severe malnutrition and improves long-term growth. Wisconsin Cystic Fibrosis Neonatal Screening Study Group. Pediatrics, 2001 Jan;107(1):1-13.

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