COMPLICATIONS - METABOLIC

C.Y. Cheung
Department Of Medicine, Queen Elizabeth Hospital, Kowloon/HONG KONG

Body: Introduction Higher body mass index (BMI) is shown to be associated with increased risk for graft failure and patient death among Caucasian renal transplant recipients. However, data concerning the impact of BMI on graft outcome in Asian renal transplant recipients is scarce. The WHO Western Pacific Regional Office proposed a modified BMI cut-off value of 23 kg/m² to define overweight and 25 kg/m² to define obesity in Asian populations. Our aim is to identify the relationships between two different BMI cut-off values at time of transplantation and graft outcome in Asian renal transplant recipients. We will also examine different factors which can predict graft survival. Methods This was a single-center retrospective cohort study which included all Asian patients who received kidney transplantation from 1^st July 1997 to 31^st July 2005 in our hospital. We analyzed two separate cohorts of patients based on the BMI at time of transplantation. Patients were first categorized into nonobese group (baseline BMI<25 kg/m²) and obese group (baseline BMI>=25 kg/m²). Analysis was then repeated using a lower BMI cut-off value and the patients were categorized into normal group (baseline BMI<23 kg/m²) and overweight group (baseline BMI>=23 kg/m²). Follow-up data were analyzed until 31^st March 2008. The primary end point was overall graft survival. Additionally, patient survival, death-censored graft survival and GFR estimated by abbreviated MDRD Study equation were investigated. SPSS 13 was used for statistical analysis. Kaplan-Meier survival curves and log-rank test were used for comparison of patient and graft survival. Associations between clinical variables and the development of graft failure were estimated using univariate analysis and multivariate Cox regression analysis. A P-value of less than 0.05 was defined as statistically significant. Results Total 131 patients were included in analysis. The median follow-up duration was 73 months (2-133 months). The mean BMI at time of transplantation was 21.8 +/- 4.0 kg/m². Using BMI cut-off value at 25 kg/m², 86.3% of patients were classified as nonobese and 13.7% as obese. The graft survival, both censored and uncensored for patient death, was significantly better in the nonobese group. Mean GFR was significantly better in the nonobese group since 6-month after transplantation. The patient survival was also significantly better in the nonobese group. Using BMI cut-off value at 23 kg/m², 34.3% of patients were classified as overweight and 65.7% of patients as normal. The patient and graft survival (both censored and uncensored) was similar between both groups. However, mean GFR was significantly better in the normal group since 6-month after transplantation. Obesity (O.R. 3.09), acute rejection (O.R. 5.68), pre-transplant DM (O.R. 3.21) and age of recipient (O.R. 1.06) were all significant independent risk factors associated with development of graft failure. Conclusion Obesity (BMI>=25 kg/m²) was significantly associated with poor renal graft function and decreased patient and graft survival in Asian renal transplant recipients. On the other hand, overweight was associated with a lower estimated GFR only. Further studies are required to validate the optimal target BMI in our renal transplant recipients.

Disclosure: All authors have declared no conflicts of interest.