Abstract: FR-PO1217
Limited Association Between Trough-Based Tacrolimus Exposure Metrics and One-Year Kidney Allograft Function: A Multicentre Cohort Study
Session Information
- Transplantation: Clinical - Rejection, Biomarkers, and Pharmacology
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Transplantation
- 2002 Transplantation: Clinical
Authors
- Ranatunga, Krishna, National Hospital of Sri Lanka, Colombo, WP, Sri Lanka
- Hewageegana, Anura Priyantha, National Hospital of Sri Lanka, Colombo, WP, Sri Lanka
- Liyanage, Uditha Prabhath, University of Colombo Department of Mathematics, Colombo, WP, Sri Lanka
- Nanayakkara, Nishantha, National Hospital Kandy, Kandy, CP, Sri Lanka
- Dayananda, Achala Priyadarshani, National Hospital of Sri Lanka, Colombo, WP, Sri Lanka
- Hewageegana, Sandith Nimhan, King's College Hospital, London, England, United Kingdom
Background
Tacrolimus therapeutic drug monitoring is a cornerstone of kidney transplant care and is widely assumed to influence graft outcomes. However, whether commonly used trough-derived exposure metrics, including time-weighted mean (TWM), intra-patient variability (IPV), and time in therapeutic range (TTR), meaningfully predict short-term graft function remains uncertain.
Methods
We conducted a multicentre retrospective cohort study of 335 adult kidney transplant recipients from two tertiary centres in Sri Lanka. Tacrolimus exposure metrics were derived from trough concentrations between 3 and 12 months post-transplant. Multivariable linear regression models assessed associations with estimated glomerular filtration rate (eGFR) at 12 months and change in eGFR between 3 and 12 months, adjusting for recipient, donor, and transplant-related covariates.
Results
Tacrolimus exposure demonstrated substantial heterogeneity, with moderate IPV (26.1 percent plus/minus 14.5) and low TTR (14.1 percent plus/minus 14.3). None of the exposure metrics were independently associated with 12-month graft function: TWM (beta minus 0.64, p equals 0.281), IPV (beta minus 0.11, p equals 0.147), and TTR (beta minus 0.005, p equals 0.950). No associations were observed with change in graft function. In contrast, recipient age, donor age, and 3-month graft function were consistent independent predictors. Model performance was similar across exposure metrics, with no improvement in explanatory power.
Conclusion
Trough-based tacrolimus exposure metrics were not associated with short-term graft function, demonstrating a dissociation between commonly used pharmacokinetic surrogates and one-year renal outcomes. These findings indicate that reliance on trough-derived tacrolimus metrics to assess short-term graft outcomes may be misplaced, with early graft function emerging as the dominant determinant.
Acknowledgment
We gratefully acknowledge the contributions of the clinical and laboratory staff of the participating transplant centres in Sri Lanka for their support in patient care and data collection. We extend our sincere thanks to all patients whose clinical data made this study possible. We did not receive external funding for this study.
Time-weighted mean (TWM) demonstrated no significant correlation with 12-month graft function measured by eGFR (estimated glomerular filtration rate)