BACKGROUND: Reports of indeterminate lupus anticoagulant (LAC) results are common; however, no published data on their prevalence or clinical significance are available. We investigated the prevalence and clinical characteristics of patients with indeterminate LAC. METHODS: We retrospectively reviewed the clinical and serologic characteristics of 256 unselected patients with LAC results. RESULTS: Indeterminate results were observed in 32.7% of LAC profiles that were least frequent (25.4%) when activated partial thromboplastin time (aPTT) was normal, most frequent (39.8%) when aPTT was elevated, and were observed in 35% of patients taking warfarin. The final indeterminate LAC cohort included 65 patients with a mean follow-up of 18 months. Malignancy and autoimmune disease were present in 29% and 25% of patients, respectively. The most common thrombotic events were deep vein thrombosis (DVT) (28%), cerebral ischemic stroke (14%) and pulmonary embolism (14%). Patients with indeterminate results were more likely to be men, older, and with a history of DVT, superficial thrombosis, or myocardial infarction than patients with negative tests (N=106). Concurrent warfarin therapy was more prevalent in the indeterminate group, but was not statistically significant. In the multivariate analysis, none of the variables showed statistical significance. During follow-up, 10 of 16 patients with indeterminate results showed change in classification upon retesting. CONCLUSION: Patients with indeterminate LAC results were common, and their clinical characteristics differed from those with negative results. There is a need for a prospective study of the clinical history of patients with indeterminate LAC results.
Antibodies, Antiphospholipid ; Antiphospholipid Syndrome ; Autoimmune Diseases ; Cohort Studies ; Follow-Up Studies ; Humans ; Lupus Coagulation Inhibitor ; Male ; Multivariate Analysis ; Myocardial Infarction ; Partial Thromboplastin Time ; Prevalence ; Pulmonary Embolism ; Retrospective Studies ; Stroke ; Thrombosis ; Venous Thrombosis ; Warfarin

BACKGROUND: Most children with acute lymphoblastic leukemia (ALL) receive blood transfusions. Transfusions may affect ALL outcomes through transfusion-related immunomodulation (TRIM). METHODS: We analyzed overall survival (OS) and event-free survival (EFS) in relation to leukocyte reduced and irradiated (LR/IRR) blood products transfused during the induction phase in 136 children with ALL. Hazard ratios (HRs) for death and relapse were estimated through Cox regression analysis. RESULTS: One hundred and twenty patients (89%) were transfused with packed red blood cells (PRBCs) and 79 (58%) with single donor platelets (SDPs). The median number of transfusions was 2 (interquartile range [IQR]=1-3 events) and 1 (IQR=0-3 events) for PRBCs and SDPs, respectively. Patients who had white blood cell (WBC) count >50,000x10(9)/L, were classified as high risk according to the high National Cancer Institute criteria, displayed a T cell phenotype, or were minimal residual disease-positive at end of induction were more likely to receive >3 transfusions during induction (P=0.001, 0.002, 0.03, and 0.01, respectively). In univariate analysis, PRBC, SDP, and fresh frozen plasma transfusions did not have any significant association with relapse or death. For PRBC transfusions, the HRs for EFS and OS were 1.02 (95% CI, 0.85-1.24; P=0. 76) and 1.03 (95% CI, 0.83-1.27; P=0.76), respectively. For SDP transfusions, HRs were 1.03 (95% CI, 0.90-1.18; P=0.64) and 0.98 (95% CI, 0.80-1.20; P=0.87) for EFS and OS, respectively. CONCLUSION: LR/IRR blood products may not confer a TRIM effect in childhood ALL and are unlikely to affect outcome.
Blood Platelets ; Blood Transfusion ; Child ; Disease-Free Survival ; Erythrocytes ; Humans ; Immunomodulation ; Leukocytes ; National Cancer Institute (U.S.) ; Phenotype ; Plasma ; Polymethacrylic Acids ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; Prognosis ; Recurrence ; Tissue Donors