Age at diagnosis and disease progression of cystic fibrosis in an area without newborn screening

Abstract

We studied age at diagnosis and disease progression of cystic fibrosis (CF) patients with a new study design, using data of 119 patients extracted from Stockholm CF Centre registry. Risk factors for overall morbidity and for lung, liver and nutritional morbidity were investigated separately using time to event methodology (Kaplan-Meier curves, proportional hazards regression). The patients were followed from: (i) healthy at diagnosis to morbidity, (ii) diagnosis with symptoms of morbidity to being free of morbidity, and (iii) free of morbidity to relapse of morbidity. Median age at diagnosis was 5.0 months. Of the patients with overall morbidity at diagnosis 50% became free of morbidity after 4.8 years; however, the patients above the age of 24 months at diagnosis had a reduced chance of becoming free of morbidity (crude hazard ratio 0.14 [95 % confidence interval 0.04, 0.45]) compared with those with diagnosis between the ages of 2 and 12 months (P<0.01). Of the healthy at diagnosis, 50% experienced overall morbidity after 1.4 years. They had a slow decline to the endpoint of the specific morbidities; 50% experienced lung morbidity after 3.4 years and liver morbidity after 4.8 years, while 50% never reached nutritional morbidity during the 10 years follow-up. We conclude that there was a disadvantage for the CF patients diagnosed after the age of 24 months with symptoms of overall morbidity at diagnosis in an area without newborn screening.