Obesity Is Associated with Poorer Outcomes Following Renal Transplantation: 1640

Introduction: Large retrospective studies in the United States have demonstrated poorer patient and graft survival in recipients with very high or very low BMI. Smaller studies in other countries have shown increased postoperative complications but no impact on patient or graft survival. We therefore aimed to assess the impact of BMI on outcome following renal transplantation in the UK population. Methods: Data for all adult renal transplants between 2000-2011 were collected from a prospectively maintained institutional database. Patients were classified according to WHO criteria as underweight (BMI < 18.5), normal weight (BMI 18.5-24.9), overweight (BMI 25-29.9) or obese (BMI >30). BMI was analysed using Kaplan Meier curves and the log rank test of significance for effect on graft survival (GS) and overall survival (OS). The effect of BMI on length of hospital stay (LOS), delayed graft function (DGF) and eGFR at years 1,3 and 5 were analysed as secondary outcome measures. Categorical variables were analysed by X2, and continuous variables by one-way ANOVA at 5% significance. Results: Height and weight were available for calculation of BMI in 1349 of 1443 adult patients transplanted in the study period. 421 recipients were overweight and 197 were obese. Obese recipients had reduced 1yr, 3yr and 5yr OS (93%, 90%, 84% respectively) compared to normal weight recipients (97%, 94%, 91% respectively, p=0.016) and underweight recipients (99%, 96%, 92% respectively, p=0.046). BMI did not affect GS. Obese patients had a significantly higher rate of DGF compared to normal weight recipients (26.4% vs. 17.0%, p=0.018) and increased LOS (median 11 days vs. 9 days, p=0.014). Overweight and obese patients had significantly worse median eGFR at 1yr (eGFR 49.6 and 47.2 respectively) compared to normal weight (eGFR 53.3) and underweight (eGFR 63.6) recipients, and at 3yrs compared to underweight recipients (all comparisons p< 0.02). Conclusion: This is the largest UK series evaluating BMI and outcome following renal transplantation. We demonstrate poorer outcome in overweight and obese patients, with higher rates of DGF, increased LOS, poorer graft function and reduced patient survival. A more detailed study of postoperative complications may reveal factors contributing to poorer outcome in the overweight and obese.