Variable tacrolimus levels accompany higher kidney-graft loss in pooled cohorts
A peer-reviewed synthesis of 10 cohort studies linked greater variation in tacrolimus blood levels with higher kidney-graft loss. The review covered 11,647 adult recipients and compared high- and low-variability groups under each study’s definitions. The observational evidence quantifies an association; it does not establish that lowering variability preserves graft function or supply a validated common clinical threshold.
Science··Morning
Ten cohorts of adult recipients
A pooled analysis of 10 cohort studies covered 11,647 adults who had received kidney transplants. It examined variability in blood levels of tacrolimus, an immunosuppressive drug used to prevent rejection. Nine cohorts were retrospective and one prospective; treatment or monitoring was not randomly assigned.[1]
The review searched medical databases for original studies and compared groups defined as having higher or lower variability. Definitions and thresholds differed between cohorts. Its main graft-loss outcome concerned permanent failure requiring dialysis or another transplant, with deaths handled separately from that outcome.[1]
The pooled association is larger than twofold
Seven studies contributed to the graft-loss comparison. Compared with the lower-variability group, the higher-variability group had a pooled hazard ratio of 2.13. Uncertainty around it extended from 1.37 to 3.32 at the 95% confidence level. This adjusted observational measure compares the rate of graft loss over follow-up; it is not a direct prediction for an individual recipient.[1]
Results varied substantially between studies, alongside differing variability measures and observation periods. The model accounted for related estimates within studies. Analyses of rejection and mortality had fewer contributing studies, leaving more uncertainty around estimates for those separate outcomes.[1]
Monitoring benefit remains untested
Greater variability was associated with graft loss, but the cohorts cannot establish that changing variability would prevent it. Unmeasured clinical differences, including donor-related factors, may affect the relationship. Different cohort thresholds also prevent the result from supplying one validated clinical cut-off.[1]
Individual participant data were unavailable for harmonising those definitions. The synthesis therefore quantifies a recurring association across adult transplant cohorts, while leaving the effects of a specific monitoring or treatment strategy for separate testing. It does not demonstrate that lowering variability preserves graft function.[1]
