Absolute Immature Platelet Count Research Articles

Plateletcrit and absolute immature platelet count are not impacted by platelet transfusions: a single-centre prospective study

BACKGROUND This is the first study in which the impact of platelet transfusions on seven platelet indices was evaluated in platelet transfusion-dependent patients admitted in the ICU. STUDY DESIGN AND METHODS Among a cohort of 21 ICU patients prospectively studied over eleven months, a total of 19 ICU patients were enrolled. Seven platelet indices were measured before and then, within 18–24 h, after platelet transfusions using the Sysmex XN-10 analyser and statistically investigated as follows: i) apheresis vs. pooled platelet transfusions; ii) pre– vs. post–platelet transfusions; and iii) platelet count (PC) increment vs. PC decrement group. RESULTS A 79.2% of platelet transfusion episodes in ICU patients showed an increase in PC increment within 18–24 h, of which 73.7% had a peak percentage immature platelet fraction (%-IPF) above 10.0% during their stay. No difference was observed in the measurements of platelet indices between the apheresis and pooled platelet transfusion doses (all p > 0.05). Of the seven platelet indices investigated, plateletcrit (PCT) and absolute immature platelet count (A-IPF) were not influenced by platelet transfusions and thus proven to be stable (0.06 vs. 0.07%, p = 0.0901 and 4.6 vs. 4.9 × 109/L, p = 0.4559, respectively), despite their close proximity to platelet transfusion. But the overall effectiveness of these indices in detecting changes over time was not hindered. CONCLUSION A-IPF and PCT are stable after platelet transfusions, regardless of whether patient’s respond to or do not respond to platelet transfusion doses. PCT and A-IPF may thus prove useful in monitoring patient transfusion support and guiding management in thrombocytopenic patients.

Immature platelet fraction as a systemic inflammation marker in patients with chronic obstructive pulmonary disease.

Recently, there has been an increasing interest to find a simple, low cost, widely available biomarker for outcome predictors in chronic obstructive pulmonary disease (COPD). Absolute immature platelet count (AIPC), the percentage of AIPC to the total platelet count (immature platelet fraction [IPF%]), symptoms, spirometry results, age-dyspne-airflow obstruction index, and C-reactive protein tests of COPD patients and control group were recorded. Neutrophil/lymphocyte, monocyte/lymphocyte, and platelet/lymphocyte ratios and Charlson comorbidity index scores were calculated. One hundred and thirty-four COPD patients and 30 healthy control subjects were included in the study. Eighty-nine patients were in exacerbation (AECOPD) and 45 of them were in stable COPD period. There was a difference between IPF% values and AIPC of COPD group and control group (3.45 ± 2.41 vs. 2.04 ± 1.12, p = 0.01; 5.87 ± 2.45 vs. 5.20 ± 3.02, p = 0.01). A positive correlation was observed between IPF% with white blood cell count and neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, monocyte/lymphocyte ratio in all patients (r = 0.352, p < 0.001; r = 0.399, p < 0.001; r = 0.186, p = 0.032; r = 0.200, p = 0.021) and AECOPD (r = 0.356, p < 0.001; r = 0.414, p < 0.001; r = 0.239, p = 0.025; r = 0.273, p = 0.010). At a cut-off of 3.4, IPF% showed the highest accuracy in identifying COPD (sensitivity: 80.3%, specificity: 82.5%) using receiver-operating characteristic analysis. This is the first study to examine the relationship between AIPC, IPF%, and COPD. The higher IPF% values in COPD and the positive correlation between IPF% and other inflammatory markers are suggested that IPF may be an indicator of systemic inflammation in COPD.

Pathological Mechanisms and Novel Testing Methods in Thrombotic Thrombocytopenic Purpura.

Thrombotic thrombocytopenic purpura (TTP) is an uncommon, but potentially disabling or even deadly, thrombotic microangiopathy with a well-studied mechanism of ADAMTS13 deficiency or dysfunction. While established treatments are largely effective, the standard ADAMTS13 testing required to definitively diagnose TTP may cause delays in diagnosis and treatment, highlighting the need for rapid and effective diagnostic methods. Additionally, the heterogeneous presentation and varied inciting events of TTP suggest more variation in its mechanism than previously thought, implying three potential pathways rather than the accepted two. The recent discovery of ADAMTS13 conformation as a potential contributor to TTP in addition to the proposal of using the absolute immature platelet count (A-IPC) as a biomarker, present novel areas for monitoring and treatment. A-IPC in particular may serve as a more rapid and accurate diagnostic test to distinguish TTP from non-TTP TMAs and to monitor treatment response and relapse. These considerations highlight the need to further study TTP in order to improve best practices and patient care.

Incidence of Thrombocytopenia in NICU and Its Association with Immature Platelet Fraction and Absolute Immature Platelet Count: A Cross-sectional Study

Introduction: Neonatal Thrombocytopenia (TCP) is frequently encountered in the Neonatal Intensive Care Unit (NICU), occurring either due to decreased production or increased destruction of platelets. This condition often leads to increased platelet transfusions in a NICU setting. Immature Platelet Fraction (IPF) and Absolute Immature Platelet Count (AIPC) are hypothesised to be surrogate markers of bone marrow activity and can help in differentiating between TCP caused by decreased production or increased destruction. Aim: To estimate the incidence of neonatal TCP in newborns admitted to a tertiary care NICU and to investigate the association of IPF percentage and AIPC values with the cause of TCP. Materials and Methods: This cross-sectional study was conducted in the Department of Paediatrics and Neonatology at Dr. D.Y. Patil Medical College, Navi Mumbai, Maharashtra, India, from April 2021 to May 2022. All 46 newborns admitted to the NICU with TCP were enrolled in the study. The total number of NICU admissions during the study period was used to calculate the incidence. The Complete Blood Count (CBC) with reticulocyte count and peripheral smear was examined using the impedance technique. The IPF and AIPC values were determined using an automated CBC counter based on flow cytometry principles. Statistical analysis was performed using the Chi-square test. Results: The study included a total of 46 neonates with TCP, with an incidence rate of 6.14%. Among the patients with TCP, 18 (39.13%) had mild, 17 (36.95%) had moderate, and 11 (23.91%) had severe TCP. The majority of neonates (21.7%) had a significant maternal history of Pregnancy Induced Hypertension (PIH). Of the neonates with TCP, 42 (91.3%) had high IPF and 4 (8.6%) had normal IPF. Regarding AIPC, 29 (63.04%) had normal values, 11 (23.91%) had high values, and 6 (13%) had low values. No significant association was found between IPF and AIPC values and the diagnosis of TCP in this study. Conclusion: The present study concludes that IPF and AIPC investigations cannot be recommended as markers to confirm the cause of TCP.

Pretreatment Absolute Immature Platelet Count is a Promising Predictor of Response to Short-Term Dexamethasone Monotherapy or Combination Therapy in Newly Diagnosed Adult Primary Immune Thrombocytopenia.

Reliable indicators that can predict drug responsiveness in primary immune thrombocytopenia (ITP) patients are urgent. We aimed to establish a reference interval of percentage of immature platelet fraction (IPF%) and absolute immature platelet count (A-IPC), and assess their efficacy in discriminating ITP patients from controls, especially their predictive value for responsiveness to drug treatment. We retrospectively studied 72 treatment-naive adult patients with ITP who received Dexamethasone monotherapy or combination therapy. Baseline (pretreatment) information was collected from medical records. Reference intervals for A-IPC and IPF% were established based on controls and their effectiveness in discriminating ITP patients from controls was assessed. Predictive value of pretreatment IPF% and A-IPC at four co-primary endpoints of treatment response in patients were investigated. The 95% reference intervals for A-IPC and IPF% were (2.7-15.6) × 109/L and 1.2%-7.3%, respectively. Both A-IPC and IPF% had excellentdiscrimination ability for ITP patients from controls. It showed highly statistically significantdifferences in pretreatment A-IPC for predicting treatment response at day 7 between responders and non-responders, but not at days 14, 21 and 28. Pretreatment A-IPC had the higher area under the ROC curve with a cut-off of 0.86 than that of IPF% with a cut-off of 14.5% in predicting the treatment response in ITP patients at day 7. Pretreatment A-IPC exhibited acceptable predictive power and could be a promising predictor of response to short-term Dexamethasone monotherapy or combination therapy at day 7 in ITP patients.

Stability over time of immature platelet fraction and comparison between EDTA and citrated whole blood samples.

Immature platelets (IP) are the youngest circulating platelets, released from megakaryocytes, and demonstrating increased dimensions, significant RNA content, and enhanced activity. Immature platelet research focuses on a differential diagnostic help in patients with thrombocytopenia. The objectives of this study were to compare the variability of IP in citrate and EDTA samples, and to determine stability over time. Fifty-six patients were included for comparison between EDTA and citrate whole blood sample collection. Among the patients, 28 had thrombocytopenia (platelet count < 150G/L). Platelet measurement impedancemetry and fluorimetry were performed with Sysmex XN-9000. The immature platelet fraction (IPF) and absolute immature platelet count (A-IPC) were determined with a fluorescent method. The mean value of platelet count with fluorescence was, in EDTA sample, 215 ± 171 and, in citrate sample, 153 ± 118 G/L. No significant difference was observed between IPF between EDTA and citrate (7.74 ± 6.68% vs. 8.45 ± 7.37%, p = 0.69), respectively. With the Bland-Altman analysis, the mean difference in the EDTA sample, between 1 and 24 h, was 8.06 ± 6.96% and 8.73 ± 7.12% for IPF, whereas in the citrate sample, between 1 and 6 h, it was 8.60 ± 7.29% and 7.54 ± 6.97%, for IPF. Comparing 1 h EDTA sample with 6 h citrate sample, the variance ratio was 0.974 (95% CI: 0.864-1.084) in IPF. We confirmed the potential to conduct IP measurements up to 24 h in the EDTA sample and IPF measurements in the citrate sample for up to 6 h. These results may be useful for the use of IPF, which is a promising parameter whose interest in clinical practice and standardization is not yet well defined.

Comparison of absolute immature platelet count to the PLASMIC score at presentation in predicting ADAMTS13 deficiency in suspected thrombotic thrombocytopenic purpura

IntroductionThrombotic thrombocytopenic purpura (TTP) demands rapid initiation of therapeutic plasma exchange to avoid severe complications associated with it. ADAMTS13 activity <10% defines TTP, however, this is a send-out test at most institutions. We have previously reported our experience looking at absolute immature platelet counts (A-IPC) in TTP patients. Thus, we compared A-IPC on admission to the PLASMIC score to predict ADAMTS13 deficiency. Materials and methodsOf seventy-two patients identified, 52 met inclusion criteria. All patients were suspected of new-onset TTP and had A-IPC on admission. Of these patients, 25/52 were later shown to have ADAMTS13 <10%, defined as TTP group, and 27/52 had ADAMTS13 >10% and are henceforth classified as non-TTP. ResultsPatients with TTP were found to have A-IPC below reference range (<1.5 × 109/L) and responded to therapy as shown by fold-increases in A-IPC (p < 0.0001), neither seen in non-TTP patients. A-IPC had a significant correlation with ADAMTS13 deficiency (p = 0.0001) with high sensitivity, specificity, positive and negative predictive values. Comparison of A-IPC to PLASMIC score indicated that the former identified all TTP patients compared to PLASMIC score even in patients obtaining scores of 4 and 5. Finally, Receiver Operating Characteristic curves showed A-IPC had area under the curve of 0.986. ConclusionsA-IPC below reference range and A-IPC fold-increases were only observed in TTP patients. There was strong association between A-IPC and ADAMTS13 deficiency and A-IPC predicted patients with ADAMTS13 deficiency. Future larger studies are needed to determine ways to apply findings in suspected TTP patients.

Routine and Advanced Laboratory Tests for Hemostasis Disorders in COVID-19 Patients: A Prospective Cohort Study.

Background: Thrombosis is frequent during COVID-19 disease, and thus, identifying predictive factors of hemostasis associated with a poor prognosis is of interest. The objective was to explore coagulation disorders as early predictors of worsening critical conditions in the intensive care unit (ICU) using routine and more advanced explorations. Materials: Blood samples within 24 h of ICU admission for viscoelastic point-of-care testing, (VET), advanced laboratory tests: absolute immature platelet count (A-IPC), von Willebrand-GPIb activity (vWF-GpIb), prothrombin fragments 1 + 2 (F1 + 2), and the thrombin generation assay (TGA) were used. An association with worse outcomes was explored using univariable and multivariable analyses. Worsening was defined as death or the need for organ support. Results: An amount of 85 patients with 33 in critical condition were included. A-IPC were lower in worsening patients (9.6 [6.4–12.5] vs. 12.3 [8.3–20.7], p = 0.02) while fibrinogen (6.9 [6.1–7.7] vs. 6.2 [5.4–6.9], p = 0.03), vWF-GpIb (286 [265–389] vs. 268 [216–326], p = 0.03) and F1 + 2 (226 [151–578] vs. 155 [129–248], p = 0.01) were higher. There was no difference observed for D-dimer, TGA or VET. SAPS-II and A-IPC were independently associated with worsening (OR = 1.11 [1.06–1.17] and OR = 0.47 [0.25–0.76] respectively). The association of a SAPS-II ≥ 33 and an A-IPC ≤ 12.6 G/L predicted the worsening of patients (sensitivity 58%, specificity 89%). Conclusions: Immature platelets are early predictors of worsening in severe COVID-19 patients, suggesting a key role of thrombopoiesis in the adaption of an organism to SARS-CoV-2 infection.

Immature platelet levels correlate with disease activity and predict treatment response of thrombocytopenia in lupus patients.

The immature platelet fraction (IPF) represents recently produced platelets in bone marrow and this parameter is increased in patient with primary immune thrombocytopenia (ITP). We investigated the associations between IPF and absolute immature platelet count (AIPC), and clinical parameters in systemic lupus erythematosus (SLE), which has more complex pathological mechanisms than in primary ITP. Patients with SLE were retrospectively reviewed at the University of Tokyo Hospital from May, 2012 to January, 2021. The correlations between clinical parameters and the number of immature platelets were assessed with Spearman's rank correlation coefficients. A multiple logistic regression model was used to identify the independent clinical parameters for IPF and AIPC. The difference in the distribution of time for a complete response (CR) after prednisolone (PSL) administration was also evaluated by log-rank test. A total of 282 SLE patients were enrolled, and 12.41% of those patients showed thrombocytopenia. IPF correlated with clinical parameters such as platelet count (r = -0.58), AIPC (r = 0.64) and systemic lupus erythematosus disease activity index 2000 (SLEDAI-2K) (r = 0.24). SLEDAI-2K [odds ratio (OR) (per unit increase), 1.07; 95% CI, 1.013 - 1.13] and thrombocytopenia (OR, 32.23; 95% CI, 11.072 - 93.80) were independent clinical parameters to account for IPF increase. IPF correlated with the number of bone marrow megakaryocytes (n = 19, r = 0.57). Notably, the probability of CR in response to PSL in AIPC-high patients was higher than in AIPC-low patients (hazard ratio, 4.62; 95% CI, 1.07 - 20.02). IPF correlated with disease activity of SLE and represented platelet production in the bone marrow, whereas AIPC predicted a rapid response to steroids in thrombocytopenic patients with SLE.

Investigation of the efficacy and safety of eltrombopag to correct thrombocytopenia in moderate to severe dengue patients - a phase II randomized controlled clinical trial.

Investigation of the efficacy and safety of eltrombopag to correct thrombocytopenia in moderate to severe dengue patients - a phase II randomized controlled clinical trial.

Immature platelet indices alongside procalcitonin for sensitive and specific identification of bacteremia in the intensive care unit

Hematological markers that can be rapidly analyzed and regularly monitored during a patient’s stay on ICU, and that can identify bacterial causes of sepsis are being extensively sought. The significance of platelets in early immunological responses provides justification for assessing their usefulness in the identification of bacteremia amongst sepsis patients. In this preliminary study, the full blood count, including the platelet count by impedance (PLT-I), Immature Platelet Fraction (IPF%) and absolute immature platelet count (AIPC), were analyzed in eighty-two sepsis patients daily over the first 5 days stay on ICU. C-Reactive Protein (CRP), procalcitonin (PCT), and lactate were also analyzed daily. Blood cultures confirmed or excluded the presence of bacteremia. PCT provided the earliest indicator of bacteremia, with significant differences between the two cohorts on day 1. The change in IPF% and AIPC from day 1 to day 2 (Δ IPF% and Δ AIPC) provided the most accurate indication; A combination of Δ IPF% and day 2 PCT, provided a positive predictive value and negative predictive value of 100% and 96.10%, respectively. These data provide strong justification for larger multi-center validation studies to confirm the usefulness of these platelet indices during the assessment of sepsis on the ICU.

Immature platelet fraction: A useful marker for identifying the cause of thrombocytopenia and predicting platelet recovery.

The assessment of bone marrow thrombopoietic activity in patients with thrombocytopenia is necessary to achieve an accurate diagnosis and administer effective treatment. We evaluated the discriminatory power of the immature platelet fraction (IPF) in differentiating hyperdestructive/consumptive thrombocytopenia from hypoproductive thrombocytopenia and its potential use as a predictive marker for platelet recovery. In this observational study, platelet indices, including IPF, were measured in 105 healthy individuals, 27 patients with hyperdestructive/consumptive thrombocytopenia (all with immune thrombocytopenic purpura [ITP]), and 35 patients with hypoproductive thrombocytopenia (5 with aplastic anemia and 30 with cancer who were undergoing chemotherapy) using a Sysmex XN-3000 hematology analyzer. The platelet distribution width, mean platelet volume, platelet large cell ratio, IPF, and absolute immature platelet count (AIPC) were significantly higher in the hyperdestructive/consumptive thrombocytopenia group than in the hypoproductive thrombocytopenia group (P < .001). The IPF showed the highest difference between the two patient groups (200%). Receiver operating characteristics analysis that showed the IPF had the largest area under the curve among all the platelet indices analyzed; its cut-off value was 2.3%. The IPF decreased 3 to 4 days in advance of platelet count elevation in patients with ITP, whereas the delta AIPC increased 3 days in advance. Furthermore, the IPF and delta AIPC increased 5.5 days and 8.5 days, respectively, before platelet counts increased up to 130.0 × 10/L in cancer patients receiving chemotherapy. These data demonstrated that the IPF and delta AIPC are both excellent indicators of the etiology of thrombocytopenia and predictive markers for platelet recovery.

P331Effect of exercise stress test on platelet function in patients with recent acute myocardial infarction

Abstract Background Exercise-based cardiac rehabilitation for coronary artery disease (CAD) is associated with lower cardiovascular mortality. On the other hand, acute strenuous exercise has been linked to cardiovascular complications such as acute myocardial infarction (AMI) and sudden cardiac death. One of the pathophysiological mechanisms involved in these outcomes might be an increase in platelet aggregability after exercise. Although previous studies showed higher platelet aggregability after exercise among stable CAD patients on aspirin treatment, there is no data regarding the effect of exercise on platelet activity in post-AMI patients on dual anti-platelet therapy (DAPT). Purpose To evaluate the effect of high-intensity exercise on platelet aggregability in sedentary post-AMI patients on DAPT. Methods Platelet function was analyzed immediately before and after maximal cardiopulmonary exercise test (CPET) on cycle ergometer utilizing a personalized ramp protocol and aiming to achieving peak exercise in around 10 min. The CPET was done within 31±4 days after uncomplicated AMI. Platelet aggregability was assessed by Multiplate®ADPtest (MP-ADP) and Multiplate® ASPItest (MP-ASPI) measured as area under the curve (AUC). Reticulated platelets were measured concomitantly to MP-ADP e MP-ASPI using a fully automated flow cytometer (Sysmex XN-2000®) to determine absolute immature platelet count (IPC) per 103/microliter. Continuous variables were expressed as means ±standard deviation or as median and 25th–75th percentiles if not Gaussian distributed. Comparisons between the pre- and post-CPET assessments were performed using Wilcoxon signed rank test. Results We analyzed 81 sedentary patients (mean age 58.3±10.1 years-old, 76.5% men) after AMI (50.6% with ST-elevation myocardial infarction, mean left ventricular ejection fraction after index event 55±11.7%, 98.8% on statin and 85.5% on beta-blocker treatment). Platelet aggregability, either by MP-ADP or MP-ASPI, and IPC were significantly increased after CPET (table). Platelet function after CPET Before CPET After CPET p-value Multiplate® ADPtest (AUC) – median (25th–75th percentiles) 32.0 (22.0–48.5) 37.0 (26.0–55.2) 0.003 Multiplate® ASPItest (AUC) – median (25th–75th percentiles) 17.0 (12.7–22.0) 22.0 (16.7–28.0) &lt;0.001 Immature platelet count (103/microliter) – median (25th–75th percentiles) 9.5 (6.8–13.8) 9.6 (6.6–16.5) 0.006 CPET: cardiopulmonary exercise test; AUC: area under the curve. Conclusion On this post-AMI population, platelet was hyperactivated after exercise stress test despite the use of DAPT. These findings suggest that, even when properly treated, post-AMI patients might be at higher risk of ischemic complications after high-intensity exercises, reinforcing the importance of tailoring exercise prescription in this population. Acknowledgement/Funding Sao Paulo Research Foundation, FAPESP

Absolute immature platelet counts in the setting of suspected heparin-induced thrombocytopenia may predict anti-PF4-heparin immunoassay testing results

BackgroundHeparin-induced-thrombocytopenia (HIT) is a disease mediated by antibodies to platelet factor 4 (PF4)-heparin complexes. Immature platelet fraction (%-IPF) and absolute immature platelet count (A-IPC) measure newly-released platelets into circulation and can prove useful in differentiating patients with thrombocytopenic presentations due to consumptive or hypoproduction processes. Therefore, we evaluated utility of A-IPC in a cohort of thrombocytopenic patients suspected of HIT. Patients and MethodsTwenty-six thrombocytopenic patients (<150 × 109/L) tested for anti-PF4-heparin and 36 non-thrombocytopenic controls were included. Platelet count, %-IPF, and A-IPC were determined at time of anti-PF4-heparin testing. ResultsSixteen patients tested anti-PF4-heparin negative and 10 tested positive. Patients with positive anti-PF4-heparin did not differ in A-IPC from normal range (7.2 ± 2.9 × 109/L vs. 7.1 ± 3.2 × 109/L respectively; p = 0.97). However, there was a significant A-IPC decrease in patients negative for anti-PF4-heparin compared to normal range and those testing anti-PF4-heparin positive (4.2 ± 3.1 × 109/L vs. 7.1 ± 3.2 × 109/L vs. 7.2 ± 2.9 × 109/L respectively, p < 0.01). An A-IPC of greater than 5 × 109/L characterized 80% of anti-PF4-heparin positive cases. ConclusionA-IPC measurements can complement anti-PF4-heparin testing of patients suspected of HIT while potentially predicting anti-PF4-heparin immunoassay results.

Decreased platelet count in children with epilepsy treated with valproate and its relationship to the immature platelet fraction.

This study examined relationships between valproate (VPA) and platelet count and immature platelet fraction (IPF). We compared the platelet count and IPF among three groups of children: those treated with VPA, those treated with other antiepileptic drugs (AEDs), and a reference group. IPF was measured using flow cytometry, and absolute immature platelet count (A-IPC) was calculated. The platelet count was significantly lower in the VPA group than in other AED and reference groups. In all groups, IPF was negatively correlated with platelet count. IPF was significantly higher in the VPA group than in the reference group, whereas A-IPC was similar among all groups. After stratification of the platelet count, IPF and A-IPC of the three groups did not differ significantly in any strata. No relationship was observed between serum VPA level and platelet count, IPF, or A-IPC. Our study suggests that VPA is associated with a decreased platelet count, although thrombocytopoiesis is not affected, even in children with a reduced platelet count. The suppression of platelet production in the bone marrow is unlikely to be the cause of thrombocytopenia in patients treated with VPA.

Comparison of Immature Platelet Count to Established Predictors of Platelet Reactivity During Thienopyridine Therapy

BackgroundPrevious data suggest that reticulated platelets significantly affect antiplatelet response to thienopyridines. It is unknown whether parameters describing reticulated platelets can predict antiplatelet response to thienopyridines. ObjectivesThe authors sought to determine the extent to which parameters describing reticulated platelets can predict antiplatelet response to thienopyridine loading compared with established predictors. MethodsThis study randomized 300 patients undergoing elective coronary stenting to loading with clopidogrel 600 mg, prasugrel 30 mg, or prasugrel 60 mg. Adenosine diphosphate (ADP)-induced platelet reactivity was assessed by impedance aggregometry before loading (intrinsic platelet reactivity) and again on day 1 after loading. Multiple parameters of reticulated platelets were assessed by automated whole blood flow cytometry: absolute immature platelet count (IPC), immature platelet fraction, and highly fluorescent immature platelet fraction. ResultsEach parameter of reticulated platelets correlated significantly with ADP-induced platelet reactivity (p < 0.01 for all 3 parameters). In a multivariable model including all 3 parameters, only IPC remained a significant predictor of platelet reactivity (p < 0.001). In models adjusting each of the 3 parameters for known predictors of on-treatment platelet reactivity including cytochrome P450 2C19 (CYP2C19) polymorphisms, age, body mass index, diabetes, and intrinsic platelet reactivity, only IPC prevailed as an independent predictor (p = 0.001). In this model, IPC was the strongest predictor of on-treatment platelet reactivity followed by intrinsic platelet reactivity. ConclusionsIPC is the strongest independent platelet count–derived predictor of antiplatelet response to thienopyridine treatment. Given its easy availability, together with its even stronger association with on-treatment platelet reactivity compared with known predictors, including the CYP2C19*2 polymorphism, IPC may become the preferred predictor of antiplatelet response to thienopyridine treatment. (Impact of Extent of Clopidogrel-Induced Platelet Inhibition During Elective Stent Implantation on Clinical Event Rate—Advanced Loading Strategies [ExcelsiorLOAD]; DRKS00006102)

Immature platelet fraction predicts coagulopathy-related platelet consumption and mortality in patients with sepsis

IntroductionThe diagnostic and prognostic value of immature platelet fraction (IPF) in sepsis has not been determined. This study aimed to assess whether IPF is an early predictor of platelet decline due to coagulopathy and is associated with mortality in patients with sepsis. Materials and methodsIn total, 149 patients with a platelet count of ≥80×103/μL on intensive care unit admission (101 with sepsis, 48 controls without sepsis) were prospectively evaluated. We measured IPF on admission and observed for development of subsequent platelet count decline (defined as a >30% decrease or <80×103/μL) in 5days, and mortality at 28days. The absolute immature platelet count (AIPC) was calculated to evaluate thrombopoiesis. ResultsForty-seven patients with sepsis subsequently developed a decrease in platelet count. The IPF was highest in patients whose platelet count decreased, followed by patients without a decrease in platelet count and controls (median, 4.3% [3.1%–8.1%] vs. 3.7% [2.6%–4.6%] vs. 2.1% [1.6%–3.5%], respectively; P<0.0001). The AIPC was similar in patients with and without a decrease in platelet count (7.6 [4.2–10.0] vs. 5.9 [4.2–8.7]×103/μL, respectively; P=0.32). Coagulation derangement was more severe in patients who did than did not subsequently develop a decreased platelet count. Cox regression and receiver operator characteristic curve analysis revealed that IPF was a strong independent predictor of mortality, with accuracy similar to a standard prognostic scoring system. ConclusionsThe admission IPF in septic patients predicts a subsequent decrease in platelet count, indicating platelet consumption with ongoing coagulopathy and risk of poor prognosis.

Absolute immature platelet count may predict imminent platelet recovery in thrombocytopenic children following chemotherapy

Immature platelets are the youngest circulating platelets and they reflect the rate of thrombopoiesis. The immature platelet fraction (IPF) or the absolute immature platelet count (AIPC) may predict platelet count recovery following chemotherapy-induced thrombocytopenia in pediatric patients and help guiding prophylactic platelet transfusion therapy. To test IPF and AIPC as predictors of platelet recovery, 19 children with platelet nadirs of less than 20 × 10(9)/L after chemotherapy were prospectively enrolled. IPF, platelet count, and C-reactive protein (CRP) were analyzed in 416 paired samples from 37 patients with malignancies to test if IPF-levels were CRP dependent. A significant increase of 0.6 × 10(9)/L in AIPC was seen between 1 and 2 days prior to platelet count recovery. No predictive day-to-day differences were found for IPF. Platelet count recovery did not occur significantly earlier for patients with a peak IPF > 10% than for those patients with a peak IPF < 10%. IPF and AIPC showed no correlation to CRP. AIPC was in contrast to IPF not influenced by platelet transfusions. AIPC increased significantly between 24 and 48 hours before platelet recovery whereas IPF showed no significant increase during the same time period. AIPC may be a better indicator than IPF for predicting platelet recovery after chemotherapy in pediatric patients.