Factors influencing treatment response of pulmonary exacerbation in children with cystic fibrosis.

Background: Pulmonary exacerbations in cystic fibrosis (CF) significantly impact morbidity and mortality. This study aimed to assess treatment response rates and identify contributing factors towards treatment response.

Methods: In this single-center, retrospective, longitudinal study spanning four years, we analyzed all pulmonary exacerbation admissions. We compared lung function at baseline, admission, end of treatment, and 6-week follow-up. Treatment response was defined as ≥95% recovery of baseline FEV1%.

Results: There were 78 children who required a total of 184 admissions. The mean duration of treatment was 14.9±2.9 days. FEV1% returned to 95% of baseline in 59% following treatment. The magnitude of the decline in lung function on admission in children who did not respond to treatment was 21.7±15.2% while the decline in children who responded to treatment was 8.3±9.4%, P<0.001. Children who experienced a decline in FEV1% greater than 40% exhibited an 80% reduced likelihood of returning to their baseline values (OR -0.8, 95% CI -0.988; -0.612). Similarly, those with FEV1% reductions in the ranges of 30-39% (OR -0.63, 95% CI -0.821; -0.439), 20-29% (OR -0.52, 95% CI -0.657; -0.383), and 10-19% (OR -0.239, 95% CI -0.33; -0.148) showed progressively lower odds of returning to baseline. Fourty-eight children required readmission within 7.7±5.4 months, children who responded to treatment had a longer time taken to readmission (8.9±6.4 months) versus children who did not respond to treatment (6.4±3.5 months), (OR: -0.20, 95% CI -0.355; -0.048).

Conclusions: A greater decline in lung function on admission and readmission within 6 months of the initial admission predicts non-response to treatment. This highlights the importance of re-evaluating follow-up strategies following discharge.