Objectives
Obesity is associated with worsening kidney allograft function. Since kidney allograft function may rapidly change throughout the course of kidney transplantation, particularly during early post-transplant period, we aim to examine association between pre-transplant obesity and development of chronic kidney disease (CKD) over several time points during post-transplant periods.
Methods
A single center retrospective cohort study included kidney transplant recipients who received kidney transplantation, between 2012 and 2015. The study population were divided into non-obese and obese groups based on pre-transplant body mass index (BMI) of < 30 and ≥30 kg/m2, respectively. Association between the obesity status and post-transplant CKD defined as estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2 was examined by multivariable Cox proportional hazard regression analysis with a time-dependent effect at 12, 24, 36, and 48 weeks post-kidney transplantation.
Results
Of all 105 patients, mean age ± SD was 54 ± 12 and 61% was female. Non-obese and obese groups were account for 64% and 36%, respectively and their corresponding mean BMI were 24.34 ± 3.54 and 34.27 ± 3.53 kg/m2 (P < 0.001). The risk of developing CKD at 12, 36, and 48 weeks post-kidney transplantation, were not significantly difference. However, at 24-week post- kidney transplantation, obese group had 71% greater the risk for CKD compared to non-obese group (Hazard ratio (HR) 1.71, P 0.049, 95% confidence interval (95%CI) 1.002, 2.908). After adjusted for age, gender, type of kidney transplantation, systolic and diastolic blood pressure at 24 weeks post-kidney transplantation, the obese group remain at higher the risk for CKD (HR 1.74, P 0.044, 95% CI 1.014, 2.985).
Conclusions
Pre-kidney transplant obesity was associated with increased risk of CKD at the early, but not at the immediate or long-term post-transplant periods independent to the baseline characteristics and blood pressure. Pathophysiological changes during different post-transplant periods including immunological or non-immunological factors may contribute to this time-dependent effects of pre-transplant obesity and CKD. Additional studies are warranted to further examine possible mechanism.
Funding Sources
None.