Correlation between cardio-pulmonary exercise test variables and health-related quality of life among children with congenital heart diseases

Abstract

Background: Health-related quality of life (HR-QoL) stands as a determinant "patient-related outcome" and correlates with cardio-pulmonary exercise test (CPET) in adults with chronic heart failure or with a congenital heart disease (CHD). No such correlation has been established in pediatric cardiology.

Methods and results: 202 CHD children aged 8 to 18 performed a CPET (treadmill n=96, cycle-ergometer n=106). CHD severity was stratified into 4 groups. All children and parents filled out the Kidscreen HR-QoL questionnaire. Peak VO2, anaerobic threshold (AT), and oxygen pulse followed a downward significant trend with increasing CHD severity and conversely for VE/VCO2 slope. Self-reported and parent-reported physical well-being HR-QoL scores correlated with peak VO2 (respectively r=0.27, p<0.0001 and r=0.43, p<0.0001), percentage of predicted peak VO2 (r=0.28, p=0.0001 and r=0.41, p<0.0001), and percentage of predicted VO2 at AT (r=0.22, p<0.01 and r=0.31, p<0.0001). Significant correlations were also observed between several HR-QoL dimensions and dead space to tidal volume ratio (VD/VT), oxygen uptake efficiency slope (OUES), oxygen pulse but never with VE/VCO2 slope. The strongest correlations were observed in the treadmill group, especially between peak VO2 and physical well-being for parents (r=0.57, p<0.0001) and self (r=0.40, p<0.0001) reported HR-QoL.

Conclusions: Peak VO2 and AT are the two CPET variables that best correlated with HR-QoL in this large pediatric cohort, parents' reports being more accurate. If HR-QoL is involved as a "PRO" in a pediatric cardiology clinical trial, we suggest using parents related physical well-being HR-QoL scores.

Clinical trial registration: ClinicalTrials.gov (number NCT01202916).

Keywords: Cardio-pulmonary exercise test; Congenital heart disease; Peak VO2; Pediatrics; Quality of life.