Is Neonatale Screening op Mucoviscidose aangewezen in België?

10 Cystic Fibrosis Neonatal Screening KCE Reports 132
2 CLINICAL OUTCOME AFTER NEONATAL
SCREENING
2.1 INTRODUCTION
Neonatal screening for CF (CF-NBS) has been in use in some areas as early as the
seventies. Initially test quality was insufficient (measuring meconium protein levels).
Later, ‘immunoreactive trypsinogen’ (IRT) in blood, a marker of pancreatic injury was
introduced. Infants with CF have a raised IRT level at birth that remains elevated in the
first weeks of life. The drawback of the IRT test is the high number of false positives.
Combining the IRT with DNA analysis or another biochemical marker (for example
‘PAP’ pancreatic associated protein) increases test performance. For systematic review,
technical aspects and references on neonatal screening algorithms we refer to chapter
6.
Several studies have shown that starting therapy very early (also in asymptomatic
children at time of diagnosis) improves clinical outcome and prognosis, ‘early’ being
specified as before 2 months of age. 46, 47 The median age at diagnosis for children with
CF diagnosed on clinical ground in Belgium however is 6 months (Belgian CF registry
data; see chapter 5).
The rationale of CF-NBS is thus to lower the age at diagnosis and institute adequate
treatment and follow-up also in pre-symptomatic infants. The ultimate goal is to
improve long term prognosis.
Knowing that CF patients are generally well nourished at birth but develop PI in 90%
(around 60% within the first weeks of life 48 ), delayed diagnosis will lead to severe
malnutrition. The CF lung is normal at birth but lung disease usually develops as early as
2 months. Pseudomonas aeruginosa (PA) infection and colonization occur in one out of 3
undiagnosed patients.
The aims of CF-NBS are :
• Early treatment with pancreatic enzyme replacement therapy (PERT), diet
and fat soluble vitamins to improve long term nutritional status
• Early therapy to prevent and treat lung infection by close monitoring of
sputum cultures in order to slow down progression of lung disease and to
diminish treatment burden 49-52
• Avoiding a diagnostic odyssey with resulting parental stress
• Allowing genetic counselling for future pregnancies
• Reducing burden and thus cost of treatment by preventing complications.
NBS may however carry risks:
• Parental stress around false positive diagnosis and dubious diagnosis
• In order to set-up the necessary early follow-up and treatment, infants
even when presymptomatic, may be exposed to nosocomial infections,
and
• Late diagnosis in initial false negative tested children (see also chapter 3.)
In the following part we summarize existing literature on clinical outcome. Possible
harms are reviewed in Chapter 3.