Patient registries for cystic fibrosis: New answers to old questions but are they definitive?

Abstract

There has been a long standing controversy concerning the efficacy of inhaled steroids for cystic fibrosis lung disease because earlier studies yielded conflicting results. In this issue of The Journal, the data from the Epidemiologic Study of Cystic Fibrosis were studied by Ren et al using multivariate analysis. Their results show that initiation of inhaled corticosteroids was associated with a significant reduction in the rate of fall of FEV1. However, the therapy was also associated with decreased linear growth and increased use of hypoglycemic agents. McPhail et al from Cincinnati Children's Hospital Medical Center performed a single center analysis of outcomes in two 7-year birth cohorts. The later cohort (1993-2000) had significantly improved lung function, a slower rate of decline in lung function, and improved nutrition. Better lung function was associated with good nutrition, absence of chronic Pseudomonas aeruginosa pulmonary infection, and starting dornase alfa aerosols before age 9 years. These studies are discussed in a related editorial by Schechter of Emory University, who emphasizes the use of disease registries for evaluating clinical effectiveness and the safety of new therapies. While acknowledging their value, he also points out the limitations of observational studies which, in general, should lead to caution with the interpretation of results.