LONG-TERM FOLLOW-UP OF CHANGES IN FEV1 AND TREATMENT INTENSITY DURINGPSEUDOMONAS-AERUGINOSA COLONIZATION IN PATIENTS WITH CYSTIC-FIBROSIS

Background-Colonisation with Pseudomonas aeruginosa (PA) is a striking feature of lung involvement in cystic fibrosis. To identify the clini cal consequences of the different steps of colonisation with PA under a defined therapeutic regime (no prophylactic antibiotic treatment as long as patients had no severe pulmonary disease), their influence on pulmonary function and on therapeutic intensity was examined. Methods- Forty patients with cystic fibrosis were followed from first detection of PA (PA1), chronic PA colonisation (PAc), first mucoid PA detection (PAm), to chronic mucoid PA colonisation (PAcm). Percentage predicted forced expiratory volume in one second (FEV,), the number of intraven ous antibiotic treatment courses, and the percentage of patients on in haled antibiotics were followed retrospectively and longitudinally in relation to the different steps of PA colonisation. The annual changes in FEV, and therapeutic intensity in the two years preceding each ste p were compared with the two years following each step. Changes in FEV , were related to therapeutic intensity. Results-The mean (SD) annual changes in FEV1 (% predicted) worsened significantly only with the tra nsition to the mucoid stages (PAm: 4.6 (13.2) versus -4.3 (8.1); PAcm: 7.3 (12.0) versus -4.8 (7.4)) with a mean difference (95% CI) between before and after the transition of 8.9 (2.6 to 15.2) for PAm and 12.1 (6.4 to 17.6) for PAcm. With non-mucoid PA stages the therapeutic int ensity increased in the year of transition and with mucoid PA stages i t increased in the years following transition. Therapeutic intensity w as unrelated to changes in FEV,. Conclusion-With the treatment regime used an accelerated decrease in FEV, was successfully prevented in the non-mucoid stages but not in the mucoid stages of PA colonisation.