Lung clearance index in young children with atypical CF

Introduction: Lung clearance index (LCI) is a very sensitive marker of early lung disease in Cystic Fibrosis (CF). In Cystic Fibrosis Screen Positive Inconclusive Diagnosis (CFSPID) and in compound heterozygotes carrying at least one mutation with indefinite clinical liability (CH), respiratory symptoms are often more mild and they might begin in adulthood. In childhood usually these patients have normal spirometric values. Aims and objectives: Compare LCI among three groups of patients: CFSPID-CH, CF and controls. We wanted to find out whether it is true that CFSPID-CH have normal LCI as healthy controls. Methods: We perform and compare Spirometry test and N2-Multiple Breath Wash Out (N2-MBW, Exhalyzer D, Ecomedix) in a group of CFSPID-CH, a group of CF and a control group. Results: 9 healthy controls (mean age: 5.4 yrs), 17 CFSPID-CH (mean age: 10.4 yrs) and 37 CF patients (mean age: 7.5 yrs) were tested. Basal FEV1 was normal in all groups and it was not statistically different between them. CF had significantly higher mean LCI than CFSPID-CH (9.68 versus 7.23; p=0.004). CFSPID-CH9s LCI was higher than healthy controls but without statistical significance. Conclusions: Our data show that CFSPID-CH have a pattern of LCI that is different from the one of CF patients and is similar to the one of healthy control. LCI could be a promising technique to study pulmonary function of CFSPID-CH and could be use in the follow-up of these patients.