Annual assessment spirometry, plethysmography, and gas transfer in cystic fibrosis: do they predict death or transplantation

Abstract

Aim: The long- and short-term prognostic value of pediatric spirometry, plethysmography, and gas transfer measurements in cystic fibrosis (CF) were assessed.

Methods: Two hundred ninety-eight children with CF and >or=4 annual assessment lung function measurements at a single institution were analyzed in mid childhood. Long-term outcome was death or lung transplantation (D/T) before 2007. Short-term outcome was forced expired volume in one second (FEV(1)) z-score 1 year after the previous lung function measurements.

Results: 26/298 had a D/T outcome at median 19.5 years. A zFEV(1) < -2 aged 8 years had a positive predictive value of 67% (sensitivity 67%) for D/T in those homozygous for DeltaF508 but zFEV(1) at older ages and all genotypes was unhelpful. The ratio of residual volume to total lung capacity z-score could also predict a few D/T individuals when zFEV(1) was normal in mid childhood. Most other lung function measurements were not helpful. Matching D/T with alive groups for year of birth left prognostic utility unchanged. Only current zFEV(1) could significantly predict zFEV(1) 1 year hence (56% variability explained, P < 0.00001); no other lung function, gender, age or nutrition factor was significant.

Conclusion: The value of routine plethysmography and gas transfer measurements in CF is questionable in CF management. Detecting abnormal spirometry even at age 8 years may be too late to affect long-term outcome.