Background

Kidney transplant-associated thrombotic microangiopathy (KTA-TMA) is a multifactorial inflammatory disorder and thrombotic disease of the microvasculature. It is characterized by hemolytic anemia, thrombocytopenia, and acute renal failure, and thus requires immediate intervention to avoid irreversible kidney graft damage.

Methods

The prevalence, diagnosis, treatment, and long-term outcome of KTA-TMA were reviewed retrospectively in 1485 living kidney transplantations (1079 ABO-compatible [ABO-C] and 406 ABO-incompatible [ABO-I]) that were performed at our institutions between January 1999 and December 2015.

Results

During the study period, of the 1485 kidney transplant recipients, 24 were diagnosed as having KTA-TMA. KTA-TMA developed within 90 days after transplantation in all the cases. The overall incidence of KTA-TMA was 1.6% in our cohort, and no significant sex-related difference was found. Compared with that of the ABO-C cases, the prevalence of KTA-TMA was significantly higher in the ABO-I cases (12 cases, 3.0%; hazard ratio [HR], 2.89; p = 0.008). We created rapid diagnostic criteria (Rapid KTA-TMA Diagnostic Criteria) with the characteristic laboratory data, including percentage of fragmented red blood cells, platelet reduction rate, lactate dehydrogenase levels, and reduction rate of hematocrit level, which enable initiation of prompt treatment. By using these diagnostic criteria, 23 (95.8%) of the 24 cases were correctly diagnosed as having KTA-TMA (sensitivity, 95.8% and specificity, 100%). In most cases, plasma exchange therapies were performed and recent cases were successfully treated with eculizumab administration. In the 24 cases, 13 patients (54.2%) were successfully treated for KTA-TMA, 2 had graft loss due to TMA within 90 days, 2 had chronic antibody-mediated rejection, and 2 died with functioning grafts. Compared with the ABO-C cases, the graft failure rate in the ABO-I cases during the 90 days was worse (2.4% vs 0.4%; HR, 6.57; p < 0.001), but the 10-year graft survival rate (non-censored for death) was almost equivalent (85.8% vs 58.6%, p = 0.849).

Conclusion

ABO incompatibility is a significant risk factor of KTA-TMA, and prompt diagnosis using the Rapid KTA-TMA Diagnostic Criteria and immediate treatment may lead to good long-term outcomes.

CITATION INFORMATION: Tanabe K., Okumi M., Unagami K., Kakuta Y., Inui M., Ishida H. High Prevalence of Kidney Transplant-Associated Thrombotic Microangiopathy after ABO-Incompatible Kidney Transplantation: Risk Factors, Rapid Clinical Diagnosis, and Prompt Successful Treatment Am J Transplant. 2017;17 (suppl 3).

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