Newborn screening for cystic fibrosis in Victoria: 10 years' experience (1989-1998)

Objective: To review the effectiveness of statewide newborn screening for c ystic fibrosis (CF) in Victoria over the first 10 years of the program (198 9-1998). Design: Population study involving screening of newborns by immunoreactive trypsinogen (IRT) testing on Day 3-5, followed by either repeat IRT testing (1989-1990) or Delta F508 mutation analysis (1991-1998). Patients and setting: All babies screened for CF in a newborn screening pro gram in Victoria in 1989-1998. Main outcome measure: The diagnosis of CF. Results: Of 635 157 babies born in Victoria in the 10 years, 191 were diagn osed with CF. A further 30 cases were detected antenatally, giving an incid ence of 1/2874 (95% CI, 1/2519-1/3294). CF was detected early in 182 babies (95.3% of affected babies in the screened cohort) -136 by screening, 35 be cause they had meconium ileus, and 11 because they were siblings of older c hildren with CF. Nine cases of CF were missed by screening. Of these nine b abies, four did not have an elevated neonatal IRT level, one had a normal I RT level at repeat testing at 4-6 weeks (1989-1990), three did not have a D elta F508 mutation (1991-1998), and one had a false negative sweat test res ult. Six of the nine missed babies (67%) were diagnosed within four months of birth. Conclusion: Newborn screening for CF in Victoria has proven effective in de tecting most babies with CF in the newborn period. However, a sweat test sh ould be requested when the clinical features suggest the diagnosis of CF, e ven if the child has been screened.