Recipient obesity and outcomes after kidney transplantation: a systematic review and meta-analysis

Nephrol Dial Transplant. 2015 Aug;30(8):1403-11 doi: 10.1093/ndt/gfv214.
Abstract
BACKGROUND:

The prevalence of obesity is increasing globally and is associated with chronic kidney disease and premature mortality. However, the impact of recipient obesity on kidney transplant outcomes remains unclear. This study aimed to investigate the association between recipient obesity and mortality, death-censored graft loss and delayed graft function (DGF) following kidney transplantation.

METHODS:

A systematic review and meta-analysis was conducted using Medline, Embase and the Cochrane Library. Observational studies or randomized controlled trials investigating the association between recipient obesity at transplantation and mortality, death-censored graft loss and DGF were included. Obesity was defined as a body mass index (BMI) of ≥30 kg/m(2). Obese recipients were compared with those with a normal BMI (18.5-24.9 kg/m(2)). Pooled estimates of hazard ratios (HRs) for patient mortality or death-censored graft loss and odds ratios (ORs) for DGF were calculated.

RESULTS:

Seventeen studies including 138 081 patients were analysed. After adjustment, there was no significant difference in mortality risk in obese recipients [HR = 1.24, 95% confidence interval (CI) = 0.90-1.70, studies = 5, n = 83 416]. However, obesity was associated with an increased risk of death-censored graft loss (HR = 1.06, 95% CI = 1.01-1.12, studies = 5, n = 83 416) and an increased likelihood of DGF (OR = 1.68, 95% CI = 1.39-2.03, studies = 4, n = 28 847).

CONCLUSIONS:

Despite having a much higher likelihood of DGF, obese transplant recipients have only a slightly increased risk of graft loss and experience similar survival to recipients with normal BMI.

CET Conclusion
Reviewer: Sir Peter Morris, Centre for Evidence in Transplantation, The Royal College of Surgeons of England.
Conclusion: This systematic review and meta-analysis is directed at 17 observational studies of obesity at the time of transplantation and includes approximately 140,000 patients. Obesity in the recipient was defined as a BMI of equal or greater than 30 kg/m2. The results show a significant association between obesity and delayed graft function, and a slight but significant increased risk of death censored graft loss but no increase in patient mortality compared to recipients with a normal BMI (18.5 – 24.9). The authors point out the limitations of this study in great detail, particularly bearing in mind that only observational studies could be used, but they have handled this well. Their conclusions are that despite there being a much higher likelihood of delayed graft function, obese transplant recipients have only a slight increased risk of graft loss and a similar survival to recipients with normal BMI. It should be noted that their study has not presented an analysis of quality of the observational studies used and heterogeneity in the meta-analysis is high as might be expected.
Study Details
Aims: To investigate the association between recipient obesity and mortality, death-censored graft loss and delayed graft function (DGF) following kidney transplantation.
Interventions: A systematic review and meta-analysis was conducted and observational studies or randomized controlled trials investigating the association between recipient obesity at transplantation and mortality, death-censored graft loss and DGF were included.
Participants: 17 studies including 138,081 patients were analysed.
Outcomes: Outcomes measured were mortality risk, graft loss, and DGF.
Follow Up: Not applicable
Metadata
Funding: Non-industry funding
Publication type: Review, Systematic Review
Organ: Kidney
Language: English
Author email: jamccaughan@doctors.org.uk
MeSH terms: Body Mass Index; Delayed Graft Function; Graft Survival; Humans; Kidney Failure, Chronic; Kidney Transplantation; Obesity; Risk Factors; Survival Rate; Transplant Recipients; Treatment Outcome