Effect of degree of obesity on renal transplant outcome

Abstract

Obesity in renal transplantation has proven to affect both patient and graft survival. The scientific community seems to be split into 2 groups: one claims similar outcomes among obese and nonobese, showing only marginally increased postoperative complications; whereas the other group report a higher rate of complications, including graft loss and mortality. These results did not provide sufficient evidence to be applied in practice. In this study we analyzed the outcomes of obese recipients of renal transplant in our institution. One hundred fourteen renal transplantations were performed between January 1993 and December 2003. To estimate the impact of various degrees of obesity, the patients were allocated into 2 cohorts: Group A (body mass index [BMI] 30-34.9) and Group B (BMI 35 and greater). We analyzed patient and donor characteristics. Wound infection rates were similar in the 2 groups. The aggregate Group A and B patient survival rate was 95.6% at 1 year and 93% at 5 years. Graft survival rate was 93.9% at 1 year and 88% at 5 years. However, the analysis of the outcomes in the 2 groups with different degrees of obesity showed that the patient survival rate at 1 year in Group A was 98.9% (1 death) and 95.6% at 5 years (4 deaths). In Group B the patient survival rate at 1 year was 87.5% (3 deaths; P = .007) and at 5 years was 79.2% (P = .006). Graft survival rate in Group A was 98.9% (1 graft loss) at 1 year and 94.5% (5 graft losses) at 5 years; in Group B the graft survival rate was 75% (6 graft loss) at 1 year and 63% (9 graft losses) at 5 years (P < .0001 both at 1 and 5 years). The present study showed that overall obese recipient outcomes were as expected when evaluating the obese as a single group of recipients with a BMI >30. The overall patient and graft survival did not show particularly different results from already published studies claiming similar outcomes. However, this series showed different outcomes when we divided them into 2 groups by BMI. There was a remarkable difference between moderate obese (Group A) and morbid obese (Group B) recipients as regards patient and graft survival. It is possible that the excellent outcome in Group A may be the result of super-selection and stringent cardiovascular risk screening that is implemented for this category of potential recipients. Obese recipients with a BMI of >35 are a high-risk category. Because of the difference in the outcomes of the 2 groups, it does not seem reasonable to address obese recipients as a single group. We believe that obese patients should not be discriminated simply on the basis of the BMI. A strict evaluation should be performed before denying the opportunity to receive a renal transplant to these patients.