Birth prevalence and survival in cystic fibrosis: a national cohort study in the Netherlands.

BACKGROUND Birth prevalence and survival in patients with cystic fibrosis (CF) in the Netherlands were last investigated > 30 years ago. However, since then the birth prevalence may have decreased because of genetic counseling and an increased number of newborns of non-European descent. Although survival of CF patients has increased worldwide, a significantly lower median age at death was recently reported in the Netherlands compared with data from the United States. OBJECTIVES To analyze birth prevalence and survival in CF patients in the Netherlands, and to compare this survival data with US CF data. DESIGN Survey of all CF patients living in the Netherlands, and analysis of Dutch CF mortality statistics using data from the Dutch central statistics office, Statistics Netherlands (Voorburg, the Netherlands), and a comparison with Cystic Fibrosis Foundation (Bethesda, MD) patient registry data. SETTING All CF centers in the Netherlands and the United States. PARTICIPANTS All CF patients treated in the Netherlands on January 1, 2001, and all persons who died of CF between 1974 and 2000, and an equivalent US population. MEASUREMENTS Birth prevalence and birth cohort-specific survival. RESULTS The overall birth prevalence of CF for 1974 to 1994 was 1 in 4,750 live births, which is a considerable decrease compared with 1961 to 1965 (1 in 3,600 live births). Estimated survival to 30 years increased from 6% in the 1950-to-1954 cohort, to 36% in the 1970-to-1973 cohort. Exact survival could be calculated from 1974 onwards. Survival to 15 years increased from 72% from the 1974-to-1979 cohort, to 91% in the 1985-to-1989 cohort. Survival in the United States in the 1980-to-1984 cohort was better compared to the Netherlands, but this difference has disappeared over subsequent cohorts. CONCLUSIONS The actual birth prevalence of CF in the Netherlands is clearly lower than it was 30 years ago. Survival in CF has dramatically improved. The difference in survival between the Netherlands and the United States, as observed in the cohorts born > 20 years ago, has disappeared.