Kidney-transplant before and post-bariatric surgery are safe and effective

Kidney-transplant before and post bariatric surgery (BS) are safe and effective approaches to lose weight among end stage renal disease (ESRD) patients, according to a study by researchers from The Netherlands. However, they stressed that the severity of obesity, expected waiting time and willingness of patients to have should all be considered therefore, the optimal timing of bariatric surgery should be individualised. The outcomes were reported in the paper, ‘Bariatric surgery before and after kidney transplantation: a propensity score-matched analysis’ published in SOARD.

Figure 1: Before propensity score matching (PSM): A. Patient survival, B. Graft survival, C. Death-censored graft survival. After PSM: D. Patient survival, E. Graft survival, F. Death-censored graft survival. Kaplan-Meier method was used to assess patient and graft survival from the time of transplantation. P-values according to log-rank test. The blue curve represents the group who underwent kidney transplantation after bariatric surgery, and the red curve represents the group who underwent kidney transplantation prior to bariatric surgery.

For this retrospective cohort study, the researchers sought to assess short- and long-term outcome of ESRD patients who underwent both BS and KT and to determine the optimal timing of BS. All patients ≥18 years who have undergone both KT and BS between January 2000 and January 2020 were screened using the transplant database of Erasmus Medical Center (EMC) and University Medical Center Groningen (UMCG).


The patients were stratified into two groups according to the sequence of the two operations –

  • Group 1: patients who underwent KT before BS (KT first group)

  • Group 2: patients who underwent BS before KT (BS first group)

Patient and graft survival, duration of hospital stay and postoperative complications were analysed.


Outcomes

A total of 56 patients were eligible for the study, with 22 patients (77.3% female) in the KT first and 34 patients (67.6% female) in the BS first group. The age at transplantation in the KT first group was significantly lower than the BS first group (42.7±8.6 vs. 52.5±10.0 years, p<0.001). 14 (63.6%) and 23 (67.6%) patients were dialysis dependent before transplantation in the KT first and BS first groups respectively with a similar dialysis vintage (median [interquartile range (IQR)], 27 [19.5-44.5] vs. 27 [20-43] months; p=0.822).


A significantly higher proportion of patients in the KT first group received a retransplant compared to the BS first group (36.4% vs. 2.9%, p=0.002). No significant difference was found in the causes of ESRD, smoking history, donor sources and co-morbidities between the two groups. After PSM, 21 patients were included in the matched BS first group. There was no significant difference in age at transplantation (42.7 ± 8.6 vs. 48.3 ± 9.9 years, p<0.054) and the other baseline characteristics between the two groups.

While not reaching statistical significance, the KT first group had a shorter duration of hospital stay compared to the matched BS first group (10.5 [10.0-17.5] vs. 13.0 [10.0-15.0] days; p=0.788). The incidence of urological, vascular, incisional and cardio-cerebrovascular complications was similar between the matched BS first group and KT first group (p=0.232; p=1.000; p=0.721; p=0.607, respectively). Within 30 days after transplantation, delayed graft function (DGF) occurred in 3 (13.6%) and 4 (19.0%) patients in the KT first and the matched BS first groups. Primary nonfunction (PNF) occurred in 1 (4.8%) patient in the matched BS first group.


Mean follow-up after KT was 9.4 years in the KT first group, and 4.4 years in the BS first group. During follow-up, 5 (22.7%) and 8 (38.1%) patients in the KT first and matched BS first groups were diagnosed with biopsy-proven rejection (p=0.273). Two (9.1%) grafts were lost in the KT first group due to chronic rejection, at 66.0 and 98.1 months after transplantation respectively. Four (19.0%) grafts were lost in the BS first group due to chronic rejection (n=2), PNF (n=1) and oxalate nephropathy (n=1), at 31.7, 68.6, 0.3 and 55.1 months after transplantation. All four were included after propensity score matching (PSM). Four patients died in the BS first group with functioning grafts due to oesophageal cancer (n=1), pneumosepsis (n=1), Covid-19 infection (n=1) and drug intoxication (n=1) respectively, and 2 cases were included in the matched BS first group.


In the baseline groups, there was a significant difference in patient and graft survival (100% vs. 88.2%, p=0.041, Figure 1A; and 90.9% vs. 76.5%, p=0.009, Figure 1B), but not in death-censored graft survival (90.9% vs. 88.2%, p=0.130, Figure 1C). Whereas after PSM, graft survival was still significantly higher in the KT first group than in the matched BS first group (90.9% vs. 71.4%, p=0.009, Figure 1E), no statistical difference was found in patient survival and death-censored graft survival between the two groups (100% vs. 90.5%, p=0.082, Figure 1D; and 90.9% vs. 81.0%, p=0.058, Figure 1F).


In the KT first group, BS included sleeve gastrectomy (n=17) and Roux-en-Y gastric bypass (n=5). In the BS first group, they were sleeve gastrectomy (n=16), Roux-en-Y gastric bypass (n=16) and gastric banding (n=2). The age at BS was similar between the two groups (48.3±9.4 vs. 48.3±10.9 years, p=0.998). The preoperative BMI was not different between the KT first and BS first group (39.7 [37.9-44.0] vs. 42.0 [40.0-45.8] kg/m2, p=0.090). The median interval between KT and BS was 5.5 years (IQR 2.4-6.4) in the KT first group and 2.7 years (IQR 1.5-6.7) in the BS first group.


Mean follow-up after BS was 3.8 years in the KT first group, and 8.7 years in the BS first group. After one year’s follow-up the BMI of both groups was within the range of obesity but showed comparable reduction (30.1±6.5 vs. 32.0±4.1, p=0.215). There was no significant difference in one-year TWL and %EWL between the KT first and BS first groups (1y TWL: median [IQR], 36.0 [28.0-42.0] vs. 29.6 [21.5-40.6] kg, P=0.424; 1y %EWL: median [IQR], 74.9 [54.1-99.0] vs. 57.9 [47.5-79.4], p=0.155).


Postoperative complications were classified according to the Clavien-Dindo classification with only grade I to III to complications were found in both groups and there was no significant difference in the incidence of each grade and total complications (KT first vs. BS first, grade Ⅰ: 18.2% vs. 8.8%, p=0.415; grade II: 13.6% vs. 14.7%, p=1.000; grade IIIa: 0% vs. 2.9%, p=1.000; grade IIIb: 4.5% vs. 23.5%, p=0.074; total: 36.4% vs. 50.0%, p=0.316).


“With the major advances in robotic surgery, simultaneous KT and BS may become an additional option in the future,” the authors concluded. “Nonetheless, careful attention should be warranted in both preoperative evaluation and postoperative management and more studies are needed to elucidate the optimal treatment for this group of patients.”


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