Venous thromboembolism related to warm autoimmune hemolytic anemia: a case-control study.

BACKGROUND: The risk of venous thromboembolism (VTE) during warm autoimmune hemolytic anemia (wAIHA) is apparent in several published series. Unlike proximate disorders (autoimmune thrombocytopenia, non-immune hemolytic diseases) little is known about the presentation and risk factors for VTE in this setting. OBJECTIVE: To determine the frequency, presentation and risk factors for VTE associated with wAIHA. METHODS: We performed a single center retrospective study of adult patients (>18years) followed for wAIHA between 2009 and 2013. VTE risk factors were systematically assessed. The characteristics of patients with or without VTE were compared. VTE presentation and precipitating factors were analyzed. The Padua VTE risk score was calculated in each case. RESULTS: Forty patients were included. wAIHA was idiopathic in 24 patients (60%). Twelve patients (30%) had Evans syndrome. Mean lowest hemoglobin level was 6.6g/dl [3.7-11.5]. Eight patients (20%) presented VTE after the appearance of wAIHA, at a mean age of 52.5years. All patients had pulmonary embolus, associated with a deep venous thrombosis in 4 cases. At the time of VTE 7/8 patients had frank hemolysis (median hemoglobin level: 7g/dL) and 6/8 were outpatients with a low Padua VTE risk score. The frequency of usual VTE risk factor was similar in cases and controls. By contrast, lowest hemoglobin level was significantly lower in patients that experienced VTE (5.3 vs 7.2g/dL, p=0.016). During the first episode of wAIHA, patients with concurrent VTE had a more pronounced anemia (5.3 vs 7.4g/dL, p=0.026). At the time of VTE, anemia was more severe when no other precipitating factor was present (6 vs 8.9g.dL, p=0.04). CONCLUSION: In our cohort, 20% of patients with wAIHA presented VTE. The vast majority of VTE occurred during severe hemolytic flares and were not attributable to usual VTE risk factors. VTE prophylaxis is advisable in any patient admitted for wAIHA, irrespective of Padua VTE risk score. Prophylaxis also seems reasonable for outpatients with marked hemolysis.

Evaluation of mean sphered corpuscular volume for predicting hereditary spherocytosis.

Hereditary spherocytosis (HS) is a common red blood cell disorder. It has been shown that the mean sphered corpuscular volume (MSCV), an artificial volume, is always lower than the MCV in HS and also in some autoimmune haemolytic anaemia (AIHA). Our purpose was to assess the reliability of MSCV in routine practise, and its relevance in screening for HS. Comparison of MSCV and MCV was undertaken in a prospective study of 366 patients with anaemia. In addition, included were patients previously diagnosed to have HS (n = 33) or AIHA (n = 16). When MSCV was lower than MCV, a flow cytometric (FC) test for HS was performed. Delta (MCV-MSCV) values >9.6 fl were obtained for all HS patients. A wider spread of delta (MCV-MSCV) values was obtained for AIHA patients whose red cells gave FC test results negative for HS. In the ROC curve analysis, the determination of delta (MCV-MSCV) value has a 90.57% specificity and 100% sensitivity for HS. MSCV is a reliable automated parameter indicating possible HS. When a delta (MCV-MSCV) value is >9.6 fl, the FC test and the Coombs test are required in the differential diagnosis of HS and some AIHA.