Study Sample
We identified all hospitalized children with a diagnosis code for Cystic
Fibrosis in any position (International Classification of Diseases, 9th
ed., clinical modification [ICD-9 &10-CM] codes 277.00, 277.09 and
E84.8, E84.9). Children younger than 1 year were excluded because of
uncertainty about the true morbidity of C difficile in infants. C
difficile could be both a normal commensal flora and non-pathogenic in
infants younger than 1 year.