According to a study published in Blood Advances, researchers have developed and validated a risk score model, termed the BATAP prognostic model, with robust predictive ability to facilitate the prognostic stratification of patients with transplant-associated thrombotic microangiopathy (TA-TMA) following allogeneic hematopoietic stem cell transplantation (allo-HSCT). 

“To date, information on markers for early prognostication remains limited, and no validated predictive tool for TA-TMA is available in clinical practice,” wrote Peng Zhao of Peking University People’s Hospital in Beijing, China, and colleagues.

To develop and validate a prognostic model for TA-TMA, the team retrospectively identified 507 patients from a large cohort study who developed TA-TMA following allo-HSCT. They divided the patients into a derivation cohort (n = 269) and a validation cohort (n = 238) based on the time of transplantation to perform external temporal validation.

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Overall, patients had a median age of 28 years (interquartile range [IQR], 17-41) at the time of TA-TMA diagnosis, and the median duration from the time of transplantation to TA-TMA diagnosis was 63 days (IQR, 38-121). The 6-month and 1-year overall survival rates were 56.0% and 53.3%, respectively.

The investigators identified 5 independent prognostic factors for 6-month overall survival: patient age (odds ratio [OR], 2.371; 95% CI, 1.264-4.445), anemia (OR, 2.836; 95% CI, 1.566-5.138), severe thrombocytopenia (OR, 3.871; 95% CI, 2.156-6.950), elevated total bilirubin (OR, 2.716; 95% CI, 1.489-4.955), and proteinuria (OR, 2.289; 95% CI, 1.257-4.168).

The team constructed the BATAP (Bilirubin, Age, Thrombocytopenia, Anemia, Proteinuria) risk score model according to the regression coefficients of each variable. The validated c-statistic was 0.816 (95%, CI, 0.766-0.867) and 0.756 (95% CI, 0.696-0.817) for the internal (bootstrap method) and the external (temporal) validation, respectively.

In the BATAP risk score system, the lowest score (0 points) indicates a 7.4% risk while the highest risk score (5 points) indicates an 83.3% risk for 6-month mortality. When the investigators separated the patients into a low-risk group (0-1 points), an intermediate-risk group (2-3 points), and a high-risk group (4-5 points), they observed significant differences in the survival rates within 6 months of diagnosis (total cohort, 86.1%, 53.7%, and 20.8%, respectively) and in the Kaplan-Meier estimations of overall survival (log-rank P <.001 for pairwise comparisons).

Limitations of the study included the retrospective, single-center design, the diversity in diagnosis algorithms for TA-TMA across populations, and a lack of biomarkers of complement dysregulation.

“This predictive model might facilitate prognostication of TA-TMA and contribute to early identification of patients at higher risk for adverse outcomes,” the authors concluded. “Further studies may focus on whether these high-risk patients could benefit from early administration of intensified care or other specific management.”


Zhao P, Wu YJ, He Y, et al. A prognostic model (BATAP) with external validation for patients with transplant-associated thrombotic microangiopathy. Blood Adv. 2021;5(24):5479-5489. doi:10.1182/bloodadvances.2021004530