Less may be more when it comes to treatment of cystic fibrosis exacerbations.
A retrospective analysis of more than 1,500 patients suggests nothing is gained by extending intravenous (IV) antibiotic treatment beyond 8 to 10 days, or by giving antibiotics in the hospital.
Furthermore, therapy doesn't necessarily preserve long-term lung function, the investigators report. Forced expiratory volume in one second (FEV1) did improve after treatment but never returned to pre-exacerbation levels.
This study "highlights the need for clinicians to employ therapies that reduce the likelihood of exacerbations," the investigators write in the <em>American Journal of Respiratory and Critical Care Medicine</em> published online June 25.
Researchers at Johns Hopkins University in Baltimore, Maryland, headed by Dr. J. Michael Collaco, analyzed data for 1,535 patients in the U.S. Cystic Fibrosis Twin and Sibling Study treated between 2003 and 2007.
Their data for duration of antibiotic treatment included 2426 FEV1 measurements during 1,331 exacerbations in 492 individuals.
Corrected for baseline, the mean FEV1 continued to improve through day 8 of therapy, with maximal effect on day 10.
The duration of therapy was not associated with time until the next exacerbation, however.
"Shortening duration of therapy may yield similar results while potentially lessening disruption of family life, healthcare costs and the risk of drug toxicity," the authors say. Nevertheless, they add, prospective trials are needed to determine optimal treatment duration "as well as risk factors for slower improvement that may require longer courses of antibiotics."
For studying the effect of treatment venue, the authors included 1,278 courses of therapy in 479 people. Average lung function before and after therapy were not significantly different between the groups treated entirely in the hospital or at home.
Nor did treatment venue affect the time to the next exacerbation. Regardless of where patients were treated, the new baseline FEV1 after an exacerbation was lower than the previous baseline before the exacerbation (p<0.0001).
Linear regression analysis showed that those with greater decline in lung function before therapy experienced worse declines following treatment.
"This implies that patients with drastic drops in lung function should be monitored more closely following treatment, for even with recovery of lung function they remain at higher risk for greater long-term decline," Dr. Collaco's team advises.
In a final multivariate model, significant predictors for worse long-term decline in lung function included a greater initial drop in FEV1, presence of Pseudomonas aeruginosa, and longer duration of treatment.
"Preventing exacerbations may ultimately be more important than the approach taken to treat the exacerbation," the authors conclude.