The age at onset of chronicPseudomonas aeruginosa colonization in cystic fibrosis —prognostic significance

To evaluate the prognostic significance of the age at onset of chronicPseudomonas aeruginosa colonization (OPCP) with respect to pulmonary disease progression in patients with cystic fibrosis (CF), a retrospective long-term analysis using annual chest radiographs was performed on 54 CF patients. Thirtyseven patients (68%) were chronically colonized before the age of 12 years (group 1), 17 patients (32%) thereafter (group 2). These two groups did not significantly differ in terms of mean duration of follow up (16.2±5.9 years), sex, CF genotypes, colonization with other respiratory pathogens, supportive medical treatment and death rate during the study period. Chest radiographs were evaluated according to the Chrispin-Norman score, increasing scores representing increasing severity of respiratory disease. In both groups, progression of score means was not accelerated up to 6 years after OCPC (Scores at OCPC set 0; mean score ±SEM 6 years prior to OCPC −5.6±2.0; 10 years after OCPC +3.6±0.7 points). Patients chronically colonized prior to age 12 years (group 1) scored significantly higher between age 2 and 11 years (maximum difference at age 8 years [mean ±SEM]: 9.4±0.7 vs. 4.3±1.3 points;P= 0.002) as compared to group 2. After age 11 years, mean scores were similar in both groups, since in group 2 scores increased rapidly after age 8 years. We conclude that OCPC did not cause an immediate acceleration of CF lung disease judged by serial chest radiographs. Rapid progression in group 2 (OCPC after age 12 years) was independent of OCPC since it occurred earlier. These data indicate that OCPC may be a marker rather than the cause of respiratory disease progression.