Obesity in Living Kidney Donors: Clinical Characteristics and Outcomes in the Era of Laparoscopic Donor Nephrectomy

Julie K. Heimbach; Sandra J. Taler; Mikel Prieto; Fernando G. Cosio; Stephen C. Textor; Yogish C. Kudva; George K. Chow; Michael B. Ishitani; Timothy S. Larson; Mark D. Stegall

Disclosures

American Journal of Transplantation. 2005;5(5):1057-1064. 

In This Article

Results

Pre-operative demographic, historical and laboratory baseline data are shown in Table 1 by BMI group. There were 553 renal donors (246 men, 307 women) who underwent laparoscopic donor nephrectomy during the study period; 64% of donors were related to their recipient. Mean age was 42 ± 1 years, 39% were current or former smokers and 21% had previous abdominal surgery. These features did not differ according to BMI. Women outnumbered men twofold in the BMI < 25 group (p < 0.01). At higher ranges of BMI, the ratios of men to women were equal. Female donors had lower BMI (27.5 ± 0.3 vs. 28.6 ± 0.3 kg/m2, p < 0.05), systolic and diastolic blood pressure (129 ± 1/76 ± 1 vs. 135 ± 1/79 ± 1 mmHg, p < 0.01), fasting plasma glucose (92 ± 1 vs. 97 ± 1 mg/dL, p < 0.01), and serum creatinine (0.97 ± 0.01 vs. 1.18 ± 0.01 mg/dL, p < 0.01), compared to male donors before donor nephrectomy. Similar sex differences were evident after nephrectomy. The prevalence of historical risk factors, including personal history of hypertension, current or former smoking and family history of diabetes or cardiovascular disease did not differ by sex of donor. Lipid profiles indicated a progressive rise in total cholesterol, LDL and triglycerides, and reduced HDL with higher levels of BMI (p < 0.05).

When accepted donors were compared to 207 potential donors who were not approved for donation ( Table 2 ), hypertension was more prevalent in those not approved across all BMI groups (13—40%) with highest rates in those with BMI ≥ 35 kg/m2 (p < 0.01). Exclusion rates were higher for those with BMI ≥ 35 kg/m2 (p < 0.01). Family history of diabetes and cardiovascular disease were higher in not approved individuals with the highest rates (71% with family history of diabetes, 83% with family history of cardiovascular disease, p < 0.05 vs. normal weight) in those with BMI ≥ 35 kg/m2.

There were no perioperative donor deaths. Intra-operative complications did not differ between BMI groups occurring in 1% of surgeries ( Table 3 ). Conversion to open nephrectomy occurred in 5 of 553 cases (1%) and did not differ with respect to BMI. Conversion to open nephrectomy was associated with surgeon experience, with no conversions occurring in the last 300 cases. The mean operative time ranged from 127 ± 3 min (2 h, 7 min) in patients with BMI < 25 kg/m2 to 146 ± 6 min (2 h, 26 min) in patients with BMI ≥ 35 kg/m2. While this difference was statistically significant, the actual time difference was only 19 min.

The LOS for the initial hospitalization was similar in the four groups. The only re-operation occurred early in our experience in a non-obese patient. Wound complications (infections, seromas and hernias) were the most frequent procedure-related complications in all groups and increased with increasing donor BMI (2% < 25 kg/m2, 4% 25—29.9 kg/m2, 10% 30-34.9 kg/m2, 9% ≥ 35 kg/m2, p < 0.05). Wound infections occurred in 5% of obese patients (> 30 kg/m2) and in 1—2% of patients with a BMI < 30. This difference was not statistically significant. Hernias and seromas occurred in 1—3% of all patients. Other complications such as ileus and urinary tract complications did not differ by donor BMI.

When all procedure-related complications were added together, the patients with a BMI ≥ 35 kg/m2 had a higher complication rate compared to patients with BMI < 25 (16% vs. 5%) with wound complications accounting for the majority of the difference. However total perioperative complications for the BMI ≥ 35 group were not significantly higher compared to the mid-range BMI groups (25—29.9 and 30-34.9 kg/m2 groups).

Clinical characteristics before donor nephrectomy and at 6- to 12-month (mean 11 ± 0.34 months, range 1—49, median 11 months) follow-up for those donors with paired measurements are shown in Table 4 . Pre-nephrectomy blood pressures and fasting plasma glucose levels were higher and rose incrementally with BMI (p < 0.05) (Figure 1 and Table 4 ). Serum creatinine levels did not differ between groups. Direct measurements of iothalamate clearance indicated a rise in absolute GFR with BMI level (Figure 2A). When expressed as GFR/1.73 m2 (correction for body surface area), GFR did not differ with BMI.

Blood pressure measurements at baseline and 6—12 months following donor nephrectomy in 553 renal donors. Subjects were divided into four groups according to body mass index (BMI). Blood pressure was higher for those with BMI 25—29.9 kg/m2 and incrementally higher in those with BMI 30 kg/m2. *p < 0.05 compared to BMI < 25; +p < 0.05 compared to BMI 25—29.9, †p < 0.05 versus pre-nephrectomy.

Glomerular filtration rate determined by iothalamate renal clearance prior to (A) and 6—12 months following (B) donor nephrectomy. Subjects were divided into four groups according to BMI. Shaded columns indicate uncorrected renal clearance; open bars show renal clearance corrected for body surface area. Absolute GFR rose incrementally with BMI. Once corrected, there were no differences between groups. A similar pattern was observed following nephrectomy. *p < 0.05 compared to BMI < 25; †p < 0.05 compared to BMI 25—29.9.

Changes in blood pressure and GFR are shown in Figures 1 and 2B; blood pressure values, weight change, serum creatinine and urinary microalbumin after donor nephrectomy are shown in Table 4 . Comparable trends of rising blood pressure and absolute GFR by BMI group persisted as before donation, with higher blood pressure associated with higher BMI (p < 0.05). Blood pressure levels were unchanged or reduced following donor nephrectomy, compared to pre-nephrectomy values (p < 0.05). No differences were seen in amount of weight gain by BMI group while there were minor increases in serum creatinine and glucose levels with higher BMI group. Uncorrected GFR was greater with higher BMI after donor nephrectomy (p < 0.05) but did not differ when corrected for size (Figure 2B). There were no differences in microalbuminuria across BMI groups. Microalbumin excretion did not change, despite a reduction in GFR associated with nephrectomy.

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