Abstract
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 aimed to investigate the clinical utility of TMAO and its dietary determinants for graft failure prediction in renal transplant recipients (RTRs).
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, a decision analysis method, was performed to evaluate the clinical utility of TMAO and dietary information in the prediction of graft failure.
Among RTRs (age 52.7 ± 13.1 years; 53% males), 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 = 0.10 [95%CI, 0.01;0.19]; P=0.03), fiber intake (Std. β = -0.13 [95%CI, -0.22, -0.05]; P =0.002), and fish and seafood intake (Std. β = 0.11 [95%CI, 0.02,0.20]; 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 increased risk of graft failure, independent of age, sex, BMI, blood pressure, lipids, albuminuria and 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 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.
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.
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