Background: Reticulated platelets (RPs) are the youngest circulating platelets (PLTs). The aim of our study was to predict PLT recovery with RP percentage (RP%) and therefore to identify PLT transfusions that could be avoided after autologous peripheral blood progenitor cell (PBPC) transplantation.
Study design and methods: With a whole-blood dual-labeling flow cytometric method, RP% was prospectively assessed in 47 patients who received myeloablative chemotherapy followed by autologous PBPC transplantation. Retrospective analysis of RP evolution identified three time points: nadir of the RP% (NRP), imminent PLT recovery (IPR) corresponding to an RP% of greater than 7 percent, and PLT transfusion autonomy (PTA).
Results: Median occurrences of NRP, IPR, and PTA were on Days +5, +8, and +12 after transplantation, respectively. The RP% value at NRP (4%) was significantly lower compared to the IPR (15%) and PTA (14%). Thirty patients (64%) achieved PTA within 4 days after IPR. On Day +8, if RP% was greater than 7 percent, positive and negative predictive values for PTA within 4 days, specificity, and sensitivity were 79, 63, 66, and 76 percent, respectively. Fever between IPR and PTA was the only factor found to negatively influence PLT recovery (p = 0.02). All patients required at least one PLT transfusion. Among patients with rapid PLT recovery (IPR-PTA interval < 4 days; n = 30), half of them received one PLT transfusion after RP increase, which could be avoided.
Conclusion: These encouraging results may allow us to reduce the prophylactic PLT transfusion according to patients RP% increase.