Estimating peak oxygen uptake in adolescents with cystic fibrosis
- 1Child Development & Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands
- 2Department of Pediatric Respiratory Medicine, Cystic Fibrosis Centre Wilhelmina Children's Hospital, University Medical Centre Utrecht, Utrecht, The Netherlands
- 3Partner of Shared Utrecht Pediatric Exercise Research (SUPER) Lab, Utrecht, The Netherlands
- Correspondence to Dr Erik H J Hulzebos, Child Development & Exercise Center, Wilhelmina Children's Hospital, Room KB.02.056, University Medical Center Utrecht, P.O. Box 85090, Utrecht 3508 AB, The Netherlands;
- Received 23 November 2012
- Revised 25 June 2013
- Accepted 1 July 2013
- Published Online First 26 July 2013
Objectives To predict peak oxygen uptake (VO2peak) from the peak work rate (Wpeak) obtained during a cycle ergometry test using the Godfrey protocol in adolescents with cystic fibrosis (CF), and assess the accuracy of the model for prognostication clustering.
Methods Out of our database of anthropometric, spirometric and maximal exercise data from adolescents with CF (N=363; 140 girls and 223 boys; age 14.77±1.73 years; mean expiratory volume in 1 s (FEV1%pred) 86.82±17.77%), a regression equation was developed to predict VO2peak (mL/min). Afterwards, this prediction model was validated with cardiopulmonary exercise data from another 60 adolescents with CF (28 girls, 32 boys; mean age 14.6±1.67 years; mean FEV1%pred 85.43±20.01%).
Results We developed a regression model VO2peak (mL/min)=216.3–138.7×sex (0=male; 1=female)+11.5×Wpeak; R2=0.91; SE of the estimate (SEE) 172.57. A statistically significant difference (107 mL/min; p<0.001) was found between predicted VO2peak and measured VO2peak in the validation group. However, this difference was not clinically relevant because the difference was within the SEE of the model. Furthermore, we found high positive predictive and negative predictive values for the model for prognostication clustering (PPV 50–87% vs NPV 82–94%).
Conclusions In the absence of direct VO2peak assessment it is possible to estimate VO2peak in adolescents with CF using only a cycle ergometer. Furthermore, the regression model showed to be able to discriminate patients in different prognosis clusters based on exercise capacity.