Assessment of medullary response through cellular immaturity parameters in patients undergoing hematopoietic stem cell transplantation.

OBJECTIVE

This study aimed to evaluate relative immature platelet fraction (IPF%), absolute immature platelet fraction (A-IPF), and relative immature reticulocyte fraction (IRF%) as biomarkers of bone marrow recovery after hematopoietic stem cell transplantation and to assess their potential role in reducing prophylactic platelet transfusions.

METHODS

Sixty hematopoietic stem cell transplantation recipients (mean age, 50 years) were analyzed, and sex-specific reference ranges for IPF%, A-IPF, and IRF% were established. The predictive performance for platelet engraftment and transfusion requirements was assessed using receiver operating characteristic curve analysis, logistic regression, Fine-Gray competing risks models, Cox regression, and negative binomial modeling.

RESULTS

Only A-IPF differed significantly between groups. An A-IPF threshold greater than 1,450 predicted platelet engraftments within two days with a sensitivity of 82.1% and a specificity of 80.0%. Logistic regression demonstrated a 2.3-fold increase in the likelihood of platelet engraftment for every 1,000-unit increase in A-IPF, and Fine-Gray analysis confirmed a higher cumulative incidence of engraftment in the intermediate and high A-IPF strata (subdistribution hazard ratios, 2.71 and 3.58; p<0.001). All patients required platelet transfusions (149 events). Cox regression identified A-IPF as an independent risk factor for transfusion (hazard ratio, 1.0001; p=0.027), whereas platelet count showed a protective effect (hazard ratio, 0.959; p<0.001). Negative binomial modeling demonstrated that higher weekly mean A-IPF was associated with fewer subsequent transfusions.

CONCLUSION

A-IPF is a robust biomarker for early platelet engraftment and a clinically relevant predictor of platelet transfusion requirements in patients undergoing hematopoietic stem cell transplantation.