Cardiorespiratory fitness in pediatric renal transplant recipients.
BACKGROUND
The impact of body size, fat-free mass (FFM), and fat mass (FM) on cardiorespiratory fitness in pediatric renal transplant recipients (TX) has not been established. Study objectives were to assess maximal oxygen consumption (VO2max) in TX and controls, adjusted for body composition, and to identify risk factors for reduced fitness in TX.


METHODS
Cycle ergometry and dual-energy X-ray absorptiometry were obtained in 50 TX and 70 controls, ages 8 to 21 years. Control recruitment was targeted to include obese subjects with body mass index Z-scores comparable with TX. Allometric regression models were used.


RESULTS
TX had significantly lower height Z-scores (P<0.001) and comparable body mass index Z-scores. VO2max per body weight (mL/kg/min) and per FFM (mL/kgFFM/min) did not differ between groups. However, VO2max was 13% lower (95% CI 18, 8; P<0.001) in TX, compared with controls, adjusted for FM, FFM, sex, and race. Greater FFM, lower FM, non-black race, and male sex were independently associated with greater VO2max. Within TX, hemoglobin levels were positively associated with VO2max (P=0.04) and sirolimus use was associated with lower VO2max (P<0.01).


CONCLUSIONS
TX had significant VO2max deficits that were not captured by conventional measures (mL/kg/min). Greater FM was an independent risk factor for low VO2max. Lower fitness in TX may be related to sirolimus effects on skeletal muscle.
Sethna
Christine B
CB
Department of Pediatrics, Division of Nephrology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
Salerno
Ann E
AE
McBride
Michael G
MG
Shults
Justine
J
Paridon
Stephen M
SM
Sharma
Neha
N
Meyers
Kevin E C
KE
Leonard
Mary B
MB
D015502:Absorptiometry, Photon; D050154:Adiposity; D000293:Adolescent; D001827:Body Height; D001835:Body Weight; D016022:Case-Control Studies; D002648:Child; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D006801:Humans; D016030:Kidney Transplantation / Q000009:adverse effects* / Q000208:ethnology; D008297:Male; D010101:Oxygen Consumption; D010809:Physical Fitness; D044469:Racial Groups; D012044:Regression Analysis; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D016896:Treatment Outcome; D055815:Young Adult