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Peak oxygen uptake and mortality in children with cystic fibrosis
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  1. P Pianosi1,
  2. J LeBlanc1,
  3. A Almudevar2
  1. 1Department of Pediatrics, Dalhousie University, Halifax, Canada
  2. 2Department of Biostatistics, University of Rochester, Rochester, NY, USA
  1. Correspondence to:
    Dr P Pianosi
    Respirology Clinic, IWK Health Centre, P O Box 3070, Halifax, Canada B3J 3G9; ppianosidal.ca

Abstract

Background: Single measurements of peak oxygen uptake (V˙o2) have been shown to predict mortality in patients with cystic fibrosis (CF) although no longitudinal study of serial measurements has been reported in children. A study was undertaken to determine whether the initial, final, or the rate of fall of forced expiratory volume in 1 second (FEV1) or peak V˙o2 was a better predictor of mortality.

Methods: Twenty eight children aged 8–17 years with CF performed annual pulmonary function and maximal exercise tests over a 5 year period to determine FEV1 and peak V˙o2, magnitude of their change over time, and survival over the subsequent 7–8 years. Analysis was done using Kaplan-Meier curves and Cox proportional hazard model.

Results: Peak V˙o2 fell during the observation period in 70% of the patients, with a mean annual decline of 2.1 ml/min/kg. Initial peak V˙o2 was not predictive of mortality but rate of decline and final peak V˙o2 of the series were significant predictors. Patients with peak V˙o2 less than 32 ml/min/kg exhibited a dramatic increase in mortality, in contrast to those whose peak V˙o2 exceeded 45 ml/min/kg, none of whom died. The first, last, and rate of decline in FEV1 over time were all significant predictors of mortality.

Conclusions: Higher peak V˙o2 is a marker for longer survival in CF patients.

  • cystic fibrosis
  • exercise
  • peak oxygen uptake
  • pulmonary function
  • survival

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