Prospective evaluation of heparin-induced thrombocytopenia expert probability and 4T scores in Chinese patients with suspected heparin-induced thrombocytopenia.

BACKGROUND: Diagnosis of heparin-induced thrombocytopenia (HIT) is challenging. This study aimed to compare the diagnostic performance of HIT expert probability (HEP) and 4T scores, and to evaluate the inter-observer reliability for the 4T score in a clinical setting. METHODS: This prospective study included HIT-suspected patients between 2016 and 2018. Three hematologists assessed the HEP and 4T scores. Correlations between scores and anti-platelet factor 4 (anti-PF4)/heparin antibodies were evaluated. Receiver operating characteristic curves and area under the curve (AUC) were used to assess the predictive accuracy of these two scoring models. The intraclass correlation coefficient (ICC) was used to assess the inter-observer agreement of 4T scores between residents and hematologists. RESULTS: Of the 89 subjects included, 22 (24.7%) were positive for anti-PF4/heparin antibody. The correlations between antibody titer and either HEP or 4T scores were similar (r = 0.392, P < 0.01 for the HEP score; r = 0.444, P < 0.01 for the 4T score). No significant difference in the diagnostic performance was displayed between these two scores (AUC for the HEP score: 0.778 vs. AUC for the 4T score: 0.741, P = 0.357). Only 72 4T scores were collected from the residents, with a surprisingly low percentage of observers (43.1%) presenting the four individual item scores which made up their 4T score. The AUC of 4T score assessed by residents and hematologists was 0.657 (95% confidence interval [CI]: 536-0.765) and 0.780 (95% CI: 0.667-0.869, P < 0.05), respectively. The ICC of 4T score between residents and hematologists was 0.49 (95% CI: 0.29-0.65, P < 0.01), demonstrating a fair inter-observer agreement. CONCLUSIONS: The HEP score does not display a better performance for predicting HIT than the 4T score. With the unsatisfactory completion rate, the inter-observer agreement of 4T score in a tertiary hospital is fair, underscoring the necessity for continuing education for physicians.

Identification of seven novel mutations in the factor VIII gene in 18 unrelated Chinese patients with hemophilia A.

BACKGROUND: Hemophilia A (HA) is an X-linked inherited bleeding disorder caused by decreased activity of factor VIII (FVIII) due to heterogenous mutations in the FVIII coding gene (F8). The type of mutation plays an important role in the FVIII inhibitor formation. To date, several studies on the spectra of F8 defects have been performed in Western populations, but similar studies in Asian races are scarce. Here, we reported the distribution of the F8 gene mutations in 18 unrelated Chinese patients with HA. METHODS: Intron 22 and intron 1 inversions in the F8 gene were screened in 158 unrelated patients with HA using a long-distance PCR and multiplex PCR method. Direct sequencing of the coding region of the F8 gene was used to identify the mutations responsible for HA in 18 unrelated Chinese HA patients who were negative for intron 22 and intron 1 inversions; sequences were compared with the HAMSTeRS database. A clotting method was used to assay the FVIII activity level and the Bethesda assay was used to detect the FVIII inhibitor. RESULTS: A total of 18 different HA F8 mutations were identified, seven of which were described for the first time. These novel mutations included five small deletions, one point mutation and one small insertion. One novel mutation (4382-3 AC deletion) was associated with inhibitor development. CONCLUSION: These data extend our insight into the mechanisms by which novel amino acid mutations may lead to HA and how the HA patient genotypes influence the risk of FVIII inhibitor.

[Comparison of modified Bethesda assay and Nijmegen assay in detecting FVII inhibitor in patients with hemophilia A].

OBJECTIVE: To compare the sensitivity and practicability of modified Bethesda assay and Nijmegen assay in detecting factor VIII (FVIII) inhibitor. METHODS: Modified Bethesda assay and Nijmegen assay were used to screen FVIII inhibitors in 237 patients with hemophilia A. The buffer plus universal coagulation reference plasma (UCRP) was used to establish a standard curve for FVIII: C assay in modified Bethesda method, instead of Nijmegen plasma plus FVIII deficiency plasma in Nijmegen method. The cutoff value for positive FVIII inhibitors is > or = 0.6 BU/ml. RESULTS: The positive rate of FVIII inhibitors was 5.5% (n = 13) when using modified Bethesda assay and was 8.4% (n = 20) when using Nijmegen assay (P > 0.05). CONCLUSION: Modified standard Bethesda assay is a convenient and feasible method for detecting FVIII inhibitors.

[Frequency of factor VIII inhibitor in the patients with hemophilia A and environmental risk factors for inhibitor development].

OBJECTIVE: To screen for factor VIII inhibitor in patients with hemophilia A (HA) and explore the environmental risk factors for inhibitor development. METHODS: Totally 265 patients with HA were enrolled, including 107 consecutive inpatients and outpatients in Peking Union Medical College Hospital from April 2003 to April 2007 and 158 patients newly recruited from other hospitals. FVIII: C activity was measured by one-stage coagulation assay. FVIII inhibitor was determined using Bethesda method. RESULTS: In 265 HA patients, FVIII inhibitor was detected in 22 patients (8.3%). Nine of them (86.4%) were low responders (inhibitor titers < or = 5 000 BU/L), 3 (13.6%) were high responders (the titers > 5 000 BU/L). The frequency of FVIII inhibitor was 50% in the patients aged over 50 years, which was significantly higher than those in other age groups (P = 0. 000). Among 158 newly recruited patients with full clinical data, the frequency of FVIII inhibitor was 12.8% in patients who had received infusion of FVIII products for more than 12 doses on average each year, while it was 5.8% in whom the infusion doses were less than 12 (P = 0.156). The frequency of FVIII inhibitor was 28.5% in patients with a history of continuous infusion of FVIII products whereas it was only 1.6% in patients without such history (P = 0.000). In patients who exposed to multiple-branded or single-branded FVIII products, the frequencies of FVIII inhibitor were 9.3% and 3.9%, respectively (P = 0.229). CONCLUSION: The development of factor VIII inhibitor in patients with hemophilia A may be related to the age and the history of continuous infusion of FVIII products.

[Frequency of intron 1 inversion of factor VIII gene in Chinese hemophilia A patients with case report of a female patient with heterozygous intron 1 inversion].

OBJECTIVE: To investigate the frequency of intron 1 inversion (inv1) in FVIII gene in Chinese hemophilia A (HA) patients and to investigate the mechanism of pathogenesis. METHODS: Peripheral blood samples were collected from 158 unrelated HA patients, aged 20 (1 - 73), including one female HA patient, aged 5, and several family members of a patient positive in inv1. One-stage method was used to assay the FVIII activity (FVIII:C). Long distance PCR and multiple PCR in duplex reactions were used to screen for the intron 22 inversion (inv22) and inv1 of the FVIII coding gene (F8). The F8 coding sequence was amplified with PCR and sequenced with an automatic sequencer. RESULTS: Two unrelated patients (pedigrees) were detected as inv1 positive with a positive rate of 1.26%. A rare female HA patient with inv1 was also discovered in a positive family (3 HA cases were found in this family and regarded as one case in calculating the total detection rate). The full length of FVIII was sequenced, and no other mutation was detected. CONCLUSION: There frequency of FVIII inv1 is low in Chinese HA patients compared with other populations. Female HA patients are heterozygous for FVIII inv1 and that may be resulted from nonrandom inactivation of X chromosome.

[Risk factors analysis in 672 hospitalized patients with venous thromboembolism].

OBJECTIVES: To explore the frequency, clinical features and risk factors of venous thromboembolism (VTE) in hospitalized patients. METHODS: The frequency, demographic features, and acquired and inherited factors of in-patient cases of VTE in Peking union medical college hospital from 1994 to 2004 were analyzed retrospectively. RESULTS: Six hundred and seventy-two patients were enrolled. Among them, male to female ratio was 1.2 and the median age was 53 (14 - 92). Five hundred and eighty (86.3%) patients were at their first diagnosis with the peak ages between 40 and 50 for men and 50 and 60 for women. More common acquired risk factors were antiphospholipid antibody syndrome (APS) (32.0%), trauma / surgery (31.1%) and malignancies (17.1%). 35.7% of the patients had multiple acquired risk factors. Before the initiation of anticoagulation therapy, the activities of protein C (PC), protein S (PS) and antithrombin (AT) were measured in 94 patients. The deficiency of these three natural anticoagulants was 44.7%. Among the anticoagulant deficiencies, PC deficiency was the commonest one (13.8%). Combined deficiency of PC and AT accounted for 10.6%. 31.6% of the 94 patients had inherited plus acquired risk factors. CONCLUSIONS: Age for the first event of VTE in the men was about 10 years ahead of that in the women. The major acquired risk factors were APS, trauma/surgery and malignancies, and inherited risk factors were PC deficiency and PC + AT combined deficiencies. It seems that the coexistence of multiple risk factors plays an important role in triggering VTE.

Effects of anticoagulation protein defect in maternal plasma on spontaneous abortion.

OBJECTIVE: To investigate the mechanism of anticoagulation protein defect in the pathogenesis of unexplained recurrent miscarriage. METHODS: Fifty-seven patients with a history of unexplained abortion were enrolled as the investigation group for tests of protein C, protein S, antithrombin III (AT-III), as well as activated protein C resistance (APC-R). The control group consisted of fifty healthy women with a history of normal pregnancy and delivery. Blood samples were obtained for, measuring serum activity of protein C, protein S, AT-III, and APC-R. Patients with positive APC-R were tested for factor V (FV) Leiden gene mutation by PCR-RFLP method. RESULTS: Of the 57 patients, 12 (21.1%), 1 (1.8%), and 5 (8.8%) cases were found with protein S, protein C, and AT-III deficiency respectively, and 13 (22.8%) cases with positive results of APC-R. Of the control group, no protein C or AT-III deficiency was ever found, whereas 2 (4.0%) volunteers were presented with protein S deficiency and 3 (6.0%) with positive results of APC-R. No FV Leiden gene mutation was identified in all the patients with positive APC-R results. Late spontaneous abortion cases had higher incidence of anticoagulation protein defect than the early cases. CONCLUSION: Anticoagulation protein defect may play a role in the pathogenesis of fetal loss, especially for those occurring in late stage of pregnancy.