Incidence and Risk Factors of Obesity in Childhood Solid-Organ Transplant Recipients
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BACKGROUND: Obesity is a significant public health concern; however, the incidence post solid-organ transplantation is not well reported. METHODS: This study determined the incidence and risk factors of obesity among pediatric solid-organ transplant recipients (heart, lung, liver, kidney, multiorgan) at Hospital for Sick Children (2002-2011), excluding prevalent obesity. Follow-up occurred from transplantation until development of obesity, last follow-up or end of study. Incidence of obesity was determined overall, by baseline BMI and organ groups. Risk factors were assessed using Cox proportional-hazards regression. RESULTS: Among 410 (55% male) children, median transplant age was 8.9 (interquartile range [IQR]:1.0-14.5) years. Median follow-up time was 3.6 (IQR:1.5-6.4) years. Incidence of obesity was 65.2 (95% confidence interval [CI]:52.7-80.4) per 1000 person-years. Overweight recipients had a higher incidence, 190.4 (95% CI:114.8-315.8) per 1000 person-years, than nonoverweight recipients, 56.1 (95% CI:44.3-71.1). Cumulative incidence 5-years posttransplant was 24.1%. Kidney relative to heart recipients had the highest risk (3.13 adjusted hazard ratio [aHR]; 95% CI:1.53-6.40) for obesity. Lung and liver recipients had similar rates to heart recipients. Those with higher baseline BMI (z-score; 1.72 aHR; 95% CI:1.39-2.14), overweight status (2.63 HR; 95% CI:1.71-4.04) and younger transplant age (years; 1.18 aHR; 95% CI:1.12-1.25) were at highest risk of obesity. Higher cumulative steroid dosage (per 10mg/kg) was associated with increased risk of obesity after adjustment. CONCLUSIONS: Among all transplanted children at Hospital for Sick Children, 25% developed obesity within 5-years posttransplant. Kidney recipients, younger children, those overweight at transplant, and those with higher cumulative steroid use (per 10mg/kg) were at greatest risk. Early screening and intervention for obesity are important preventative strategies.