Association of Circulating Trimethylamine N-Oxide and Its Dietary Determinants with the Risk of Kidney Graft Failure: Results of the TransplantLines Cohort Study.
BACKGROUND
Due to the critical shortage of kidneys for transplantation, the identification of modifiable factors related to graft failure is highly desirable. The role of trimethylamine-N-oxide (TMAO) in graft failure remains undetermined. Here, we investigated the clinical utility of TMAO and its dietary determinants for graft failure prediction in renal transplant recipients (RTRs).


METHODS
We included 448 RTRs who participated in the TransplantLines Cohort Study. Cox proportional-hazards regression analyses were performed to study the association of plasma TMAO with graft failure. Net Benefit, which is a decision analysis method, was performed to evaluate the clinical utility of TMAO and dietary information in the prediction of graft failure.


RESULTS
Among RTRs (age 52.7 ± 13.1 years; 53% males), the baseline median TMAO was 5.6 (3.0-10.2) µmol/L. In multivariable regression analysis, the most important dietary determinants of TMAO were egg intake (Std. β = 0.09 [95%CI, 0.01; 0.18]; p = 0.03), fiber intake (Std. β = -0.14 [95%CI, -0.22, -0.05]; p = 0.002), and fish and seafood intake (Std. β = 0.12 [95%CI, 0.03,0.21]; p = 0.01). After a median follow-up of 5.3 (4.5-6.0) years, graft failure was observed in 58 subjects. TMAO was associated with an increased risk of graft failure, independent of age, sex, the body mass index (BMI), blood pressure, lipids, albuminuria, and the Estimated Glomerular Filtration Rate (eGFR) (Hazard Ratio per 1-SD increase of TMAO, 1.62 (95% confidence interval (CI): 1.22; 2.14, p < 0.001)). A TMAO and dietary enhanced prediction model offered approximately double the Net Benefit compared to a previously reported, validated prediction model for future graft failure, allowing the detection of 21 RTRs per 100 RTRs tested, with no false positives versus 10 RTRs, respectively.


CONCLUSIONS
A predictive model for graft failure, enriched with TMAO and its dietary determinants, yielded a higher Net Benefit compared with an already validated model. This study suggests that TMAO and its dietary determinants are associated with an increased risk of graft failure and that it is clinically meaningful.
['Flores-Guerrero|Jose L|JL|0000-0002-6094-2206', 'Osté|Maryse C J|MCJ|0000-0001-9238-1397', 'Baraldi|Paula B|PB|', 'Connelly|Margery A|MA|0000-0002-3917-592X', 'Garcia|Erwin|E|0000-0002-2956-2715', 'Navis|Gerjan|G|', 'Bakker|Stephan J L|SJL|0000-0003-3356-6791', 'Dullaart|Robin P F|RPF|0000-0002-3844-5254']
D000328:Adult D000368:Aged D015331:Cohort Studies D003430:Cross-Sectional Studies D004032:Diet D005260:Female D005919:Glomerular Filtration Rate D006084:Graft Rejection D006085:Graft Survival D006801:Humans D016030:Kidney Transplantation D008137:Longitudinal Studies D008297:Male D008744:Methylamines D008875:Middle Aged D051436:Renal Insufficiency, Chronic D012307:Risk Factors D017747:Seafood D066027:Transplant Recipients
trimethylamine-N-oxide (TMAO) net benefit diet kidney transplantation