A rapid D-dimer assay in patients presenting at the emergency room with suspected acute venous thrombosis: accuracy and relation to clinical variables

BACKGROUND AND OBJECTIVES

The measurement of D-dimer is claimed to have potential value in excluding deep vein thrombosis (DVT). New rapid methods have been proposed, but few clinical trials have assessed their performance in an emergency context. The different accuracies found between the D-dimer assays have been related to the test used (latex or ELISA), but other variables (such as population investigated, thrombus extension, duration of symptoms or concomitant heparin treatment) may be important, even if not sufficiently investigated.

DESIGN AND METHODS

We evaluated the accuracy of a rapid semi-quantitative D-dimer test (Dimertest, Dade Behring), with reference to: a) its use at an emergency unit; b) concomitant heparin administration; c) location of venous thrombosis (VT) (in the deep or superficial venous system limited to the great saphenous vein) and d) symptoms older than 14 days.

RESULTS

Two hundred and ninety-eight patients suspected of having DVT and 116 suspected of thrombosis of the great saphenous vein (GSV) were investigated. In the DVT patients, the sensitivity, specificity, positive and negative predictive values were 77.4% (95% CI 68.9-85.9), 81.4% (95% CI 76.1-86.7), 65.4% (95% CI 56.5-74.3) and 88.8% (95% CI 84.2-93.4), respectively. Excluding patients receiving heparin and those with symptoms older than 15 days, the sensitivity and negative predictive value increased to 86.3% (95% CI 78.4-94.2) and 92.8% (95% CI 88.4-97.2), respectively. In patients with GSV thrombosis, the sensitivity, specificity, positive and negative predictive values were 48% (95% CI 34.5-61.5), 90.6% (95% CI 83.2-97.9), 80.6% (95% CI 66.6-94.6) and 68.2% (95% CI 57.8-78.6), respectively. Excluding patients receiving heparin and those with symptoms older than 15 days, did not change the sensitivity or negative predictive value significantly.

INTERPRETATION AND CONCLUSIONS

Our results show that previous or concomitant heparin administration, non-acute symptoms and thrombosis localized to superficial veins reduce the clinical usefulness of the D-dimer test as the rate of false negative results is increased.

Soluble transferrin receptor as a potential determinant of iron loading in congenital anaemias due to ineffective erythropoiesis

Congenital anaemias due to ineffective erythropoiesis may be associated with excessive iron absorption and progressive iron loading. We investigated whether the soluble transferrin receptor (TfR) level was related to the degree of iron overload in 20 patients with thalassaemia intermedia, six patients with congenital dyserythropoietic anaemia type II (CDA II) and four patients with X-linked congenital sideroblastic anaemia (XLSA). All but two patients had increased serum ferritin levels (median 601 microgram/l, range 105-2855 microgram/l). Multiple regression analysis showed that 62% (P < 0.0001) of the variation in serum ferritin was explained by age and by changes in soluble TfR.

The myelodysplastic syndromes: predictive value of eight prognostic systems in 143 cases from a single institution

BACKGROUND AND OBJECTIVE

Despite the fact that several prognostic systems for myelodysplastic syndromes (MDS) have been proposed, few studies have been designed to test their effectiveness in independent patient populations. The aim of this study was to compare the prognostic value of 8 previously described prognostic systems in a series of consecutive MDS patients observed at a single institution over a 10-year period.

DESIGN AND METHODS

One hundred and forty-three patients were diagnosed as having myelodysplastic syndrome (MDS) according to the French-American-British (FAB) criteria. They were studied retrospectively in order to assess the prognostic value of the FAB classification and 7 other prognostic systems.

RESULTS

On the basis of data at diagnosis, all investigated systems effectively stratified patients into groups with different life expectancies and identified a subset of patients with poor clinical outcome. However, the systems had different outcomes concerning median survival of patients classified as low-risk, ranging from less than 3 years for the Mufti scoring system to more than 8 years for the FAB classification modified according to Rosati et al. Moreover, patient distribution into different risk categories was quite different with the different prognostic systems.

INTERPRETATION AND CONCLUSIONS

When applied to our case series, some of the prognostic systems had a much lower prognostic value than in the patient population from which they derived. This evidence suggests that testing of prognostic systems in independent case series is necessary before using the systems in clinical practice.

A randomized double-blind placebo-controlled study with subcutaneous recombinant human erythropoietin in patients with low-risk myelodysplastic syndromes

To evaluate the effect of recombinant human erythropoietin (rHuEpo) on the haemoglobin level and transfusion requirement in low-risk myelodysplastic syndromes (MDS), 87 patients were enrolled in a randomized double-blind placebo-controlled study, 44 patients were assigned to epoetin alpha (150 U/kg/d s.c. for 8 weeks) and 43 to placebo arms. MDS types were homogenous in both groups: refractory anaemia (RA) 47.7-48.8%. refractory anaemia with ringed sideroblasts (RAS) 20.5-25.6%, refractory anaemia with excess of blasts (RAEB) (blasts < 10%) 31.8-25.6%, 14/38 evaluable patients responded to epoetin alpha versus 4/37 to placebo (P=0.007). 50% of RA responded to epoetin alpha versus 5.9% to placebo (P=0.0072), RAS 37.5% v 18.2% (P=0.6) and RAEB 16.7% v 11.1% (P=1.00). 60% of non-pretransfused patients responded to epoetin alpha (Hb 8.35< or = 0.73 to 10.07+/-1.87 g/dl), whereas a slight decrease was observed in the placebo group (8.4+/-0.66 to 8.19+/-0.92 g/dl) (P=0.0004). Percentage of transfused patients was similar in both arms. Basal erythropoietin (Epo) serum levels > 200 mU/l predicted for a non-response. At week 4 sTfR levels were increased > 50% in responders (P=0.013), whereas an increase < 18% predicted for non-response (P=0.006). Leucocyte and platelet counts were not influenced by epoetin alpha treatment. Adverse events occurred in 31.8% of the rHuEpo-treated versus 42.99%) of the placebo-treated patients (P=0.2), and seven patients did not complete the course. In conclusion, rHuEpo was effective in the treatment of low-risk MDS. RA subtype, no transfusions prior to rHuEpo therapy, and low basal Epo levels were associated with higher probability of response. Soluble transferrin receptor level at the fourth week was an early predictor of response.

Myelofibrosis with myeloid metaplasia in young individuals: disease characteristics, prognostic factors and identification of risk groups

Myelofibrosis with myeloid metaplasia (MMM) is an uncommon disorder in young individuals, for whom haemopoietic stem cell transplantation offers the only possibility of cure. However, although the latter procedure is associated with significant morbidity and mortality, the clinical course of MMM is variable, with some patients surviving for less than a year and others showing an indolent course. Selection of young MMM patients for transplantation or other newer therapies is currently difficult since no prognostic data exists for this subgroup. In the present collaborative study a number of initial clinical and laboratory parameters have been evaluated for prognosis in 121 MMM patients aged 55 years or less. Median survival of the series was 128 months (95% CI 90-172). In the Cox proportional hazard regression model three initial variables were independently associated with shorter survival: Hb <10 g/dl (P <0.0001), the presence of constitutional symptoms (fever, sweats, weight loss) (P=0.001), and circulating blasts >/=1% (P=0.003). Based on the above three criteria, of the 116 patients with complete data, two groups were identified: a 'low-risk' group, characterized by 88 patients with up to one adverse prognostic factor, in whom MMM had an indolent course (median survival 176 months, 95% CI 130-188), and a 'high-risk' group, including 28 patients with two or three factors, who had a more aggressive disease (median survival 33 months, 95% CI 20-42). The above prognostic scoring system showed a high positive predictive value, sensitivity and specificity to predict survival in the series, and could be of help in making treatment decisions in young patients with MMM.

Cyclosporin-A in severe refractory anemia of myelofibrosis with myeloid metaplasia: a preliminary report

BACKGROUND AND OBJECTIVE

Severe anemia is the outstanding problem in approximately 50 percent of patients with myelofibrosis with myeloid metaplasia (MMM). The present trial was based on the considerations that abnormal immune responses are frequently associated with MMM and that cyclosporin A (Cy-A) has proven to be effective in improving anemia in autoimmune disorders. The aim of this study was to evaluate the effect of Cy-A on anemia of MMM.

DESIGN AND METHODS

We studied 10 patients with MMM and severe anemia who were not responsive to corticosteroids. Eight of them showed evidence of immune defects (direct or indirect Coombs' test, antinuclear or antimitochondrial antibodies, circulating immune complexes). Cy-A was delivered orally in two refracted doses of 5 mg per kilogram bw every day and the serum level of the drug was maintained between 100 and 200 ng/mL for at least 6 months. Clinical effects were measured by calculating a normalized transfusional need (NTN), and response was defined as about a 30% reduction in the initial transfusion requirement. Hematologic parameters, s-Epo, s-TfR, s-IL2R and lymphocyte flow cytometric analysis were also evaluated. The results were analyzed with the Student's t-test.

RESULTS

Only 6 patients completed the entire 6 months of planned therapy. Three of these responded, with one no longer needing transfusions. A high CD4/CD8 ratio was predictive of response (mean value 4.7 +/- 3.5 in responders versus 0.9 +/- 0.4 in non-responders, p = 0.06).

INTERPRETATION AND CONCLUSIONS

An immunomediated mechanism negatively affects erythropoiesis in MMM. Cy-A may be effective for patients with severe refractory anemia in this disease.

Splenectomy and risk of blast transformation in myelofibrosis with myeloid metaplasia. Italian Cooperative Study Group on Myeloid with Myeloid Metaplasia

An unexpectedly high incidence of blast transformation after splenectomy has been reported in patients with myelofibrosis with myeloid metaplasia. However, whether this was associated with spleen removal after adjustment for risk factors was not determined. We conducted a multicenter historical cohort study of patients with myelofibrosis with myeloid metaplasia diagnosed from January 1970 through January 1994. A total of 549 patients (325 men and 224 women from 22 to 92 years of age; median age, 63 years) were included in the final data set. The Cox's proportional-hazards model was used to identify factors associated with blast transformation and death. To further adjust for factors related to spleen removal assignment, a propensity score for splenectomy was estimated using recursive-partitioning analysis. Blast transformation developed in 78 patients (14.2%). Patients who underwent splenectomy developed more blast transformations than those who were not splenectomized (23 of 87 [26.4%] v 55 of 462 [11.9%]; P < .001). The cumulative incidence of blast transformation 12 years after diagnosis was 27.0% in nonsplenectomized patients and 55.0% in splenectomized ones (P = . 01). The risk factors independently predictive of blast transformation included prior splenectomy (relative risk = 2.61), platelet count less than 100 x 10(9)/L at diagnosis (relative risk = 2.45), and the presence of blasts in peripheral blood at diagnosis (relative risk = 2.31). The relative risk of blast transformation in splenectomized patients increased from 2.2 at 48 months from diagnosis to 14.3 at 12 years. Patients with the same propensity score for splenectomy showed a higher risk for blast transformation on the basis of having undergone splenectomy (P = .02). In conclusion, the risk of blast transformation is significantly increased in subjects who underwent splenectomy and appears to be independent of factors related to spleen removal assignment.

Red blood cell precursor mass as an independent determinant of serum erythropoietin level

Serum erythropoietin (sEpo) concentration is primarily related to the rate of renal production and, under the stimulus of hypoxia, increases exponentially as hemoglobin (Hb) decreases. Additional factors, however, appear to influence sEpo, and in this work, we performed studies to evaluate the role of the red blood cell precursor mass. We first compared the relationship of sEpo with Hb in patients with low versus high erythroid activity. The first group included 27 patients with erythroid aplasia or hypoplasia having serum transferrin receptor (sTfR) levels < 3 mg/L (erythroid activity < 0.6 times normal), while the second one included 28 patients with beta-thalassemia intermedia having sTfR levels > 10 mg/L (erythroid activity > 2 times normal). There was no difference between the two groups with respect to Hb (8.3 +/- 1.6 v 8.0 +/- 1.3 g/dL, P > .05), but sEpo levels were notably higher in patients with low erythroid activity (1,601 +/- 1,542 v 235 +/- 143 mU/mL, P < . 001). In fact, multivariate analysis of variance (ANOVA) showed that, at any given Hb level, sEpo was higher in patients with low erythroid activity (P < .0001). Twenty patients undergoing allogeneic or autologous bone marrow transplantation (BMT) were then investigated. A marked increase in sEpo was seen in all cases at the time of marrow aplasia, disproportionately high when compared with the small decrease in Hb level. Sequential studies were also performed in five patients with iron deficiency anemia undergoing intravenous (IV) iron therapy. Within 24 to 72 hours after starting iron treatment, marked decreases in sEpo (up to one log magnitude) were found before any change in Hb level. Similar observations were made in patients with megaloblastic anemia and in a case of pure red blood cell aplasia. These findings point to an inverse relationship between red blood cell precursor mass and sEpo: at any given Hb level, the higher the number of red blood cell precursors, the lower the sEpo concentration. The most likely explanation for this is that sEpo levels are regulated not only by the rate of renal production, but also by the rate of utilization by erythroid cells.

Erythropoietin production and erythropoiesis in compensated and anaemic states of hereditary spherocytosis

A compensated haemolytic state is defined by decreased red cell life-span without anaemia, i.e. by increased erythropoiesis in the absence of the physiological stimulus for erythropoietin (Epo) production. We evaluated s-Epo levels and the expansion of erythropoiesis (as measured by circulating transferrin receptor, s-TfR) in 32 patients with hereditary spherocytosis (HS) with the aim of verifying whether the enhanced erythropoiesis of compensated haemolysis was Epo-dependent. 20 of the patients (62.5%) had normal Hb values (> 12 g/dl in females and > 13 g/dl in males). Their compensated haemolytic state was the result of up to 8.2 times normal s-Epo and up to 3.9 times normal s-TfR levels, which were maintained by physiological regulation of erythropoiesis, as documented by the inverse dependence of Hb on s-Epo levels. Considering that patients with iron-deficiency anaemia represented the predicted physiological Epo response to anaemia, the observed/predicted in s-Epo ratio (O/P ratio) was calculated in HS patients with anaemia and was used as an index of the adequateness of Epo production. All the anaemic HS patients had an O/P ratio > 1, documenting inappropriately high s-Epo levels. This work demonstrates that the compensated haemolytic state of HS patients is produced by an inappropriately high s-Epo level, and that the pattern of Epo overproduction is a biological characteristic of the disease.

Performance characteristics of Hemox-Analyzer for assessment of the hemoglobin dissociation curve

The Hemox-Analyzer (TCS, Medical Products Division, Southampton, PA) is an automatic system for determining the oxyhemoglobin dissociation curve (ODC) and P50 values. The ODC is recorded during deoxygenation with nitrogen gas and plotted on graph paper; the oxygen tension is detected by a Clark electrode, while the oxyhemoglobin fraction (%HbO2) is evaluated by a dual-wavelength spectrophotometer. Even though this instrument has been commercially available for more than 20 years, its performance characteristics have been assessed. We evaluated the performance characteristics of the Hemox-Analyzer. P50 was tested in 28 healthy volunteers, in 16 anemic and in 9 polycythemic patients. To test its precision we evaluated both inter- and intra-assay variability. The system shows good precision: standard deviation was 0.39 for assays in duplicate, CV = 1.9% for intra-assay and CV = 3.0% for inter-assay measurements. The mean P50 values were 25.2 +/- 1.5 mmHg in normal volunteers and 27.3 +/- 1.4 mmHg in anemic patients. The Hemox-Analyzer is a simple, quick and reliable instrument for recording the oxyhemoglobin dissociation curve. Both the P50 value and observation of the fine structure of the curve can furnish information about the delivery of oxygen to tissues.

Serum erythropoietin and erythropoiesis in high- and low-fetal hemoglobin beta-thalassemia intermedia patients

Clinical data suggest that in beta-thalassemia-intermedia patients, higher levels of circulating fetal hemoglobin (HbF) are associated with greater disease severity at comparable degrees of anemia. We assessed the influence of the amount of circulating HbF on serum erythropoietin (s-Epo) levels and on serum transferrin receptor, a measure of erythropoiesis, in 30 beta-thalassemia-intermedia patients. Twenty-four showed more than 40% HbF (21 of whom with beta (0)-thalassemia) and 6 presented lower HbF levels (beta(+)-thalassemia). The two groups of patients did not differ in age (15.3 v 19 years, respectively) or degree of anemia (Hb = 8.8 g/dL in both groups). Log (s-Epo) was correlated inversely with Hb (r = -0.47; P < .01), and directly with HbF (r = .55; P < .001). Multivariate regression analysis showed that Hb and HbF were independently correlated with s-Epo levels. High-HbF patients had greater s-Epo values at the same Hb level than low-HbF patients. Considering that iron-deficiency anemia control patients represented the predicted physiologic response of s-Epo to anemia, the observed/predicted s-Epo ratio in low-HbF thalassemic patients was no different from controls, but was increased in the high-HbF group. High-HbF patients also showed an expansion of erythropoiesis as much as four to nine times the normal value at the same Hb level as low-HbF patients. We conclude that HbF exerts an independent regulatory effect on erythropoietin production and erythropoiesis that is detectable only when HbF levels exceed 40%.

Serum erythropoietin in patients with myelofibrosis with myeloid metaplasia

Serum erythropoietin levels (s-Epo) were measured by radioimmunoassay in 61 consecutive anaemic patients (Hb < 12 g/dl) with myelofibrosis with myeloid metaplasia (MMM). S-Epo was inversely correlated with Hb (r = -0.48, P < 0.0001). When observed s-Epo values were compared with predicted levels based on the relationship between s-Epo and Hb in control subjects, all but eight patients (87%) had s-Epo levels appropriate for the degree of anaemia. The observed/predicted (O/P) s-Epo ratio was significantly lower in patients with signs of active disease, and a significant inverse correlation was found between the O/P ratio and erythrokinetic measurement of the extent of erythropoiesis (r = 0.31; P = 0.02). Circulating Epo levels were appropriate for the variations in Hb during the postsplenectomy period in three patients. In conclusion, this study does not support the idea that therapy with erythropoietin should be extensively used in anaemic patients with MMM, but rather that it should be considered only in selected cases.

Variations in erythropoiesis and serum ferritin during erythropoietin therapy for anaemia of end-stage renal disease

In order to study the relationship between erythropoiesis and serum ferritin (SF) during erythropoietin (rHuEPO) therapy in the anaemia of end-stage renal disease (ESRD), 19 patients were followed without iron supplementation and at a fixed dose of the drug (40 U/kg). Twelve patients failed to attain the target haemoglobin (Hb) value, 7 of whom due to the appearance of iron deficiency. Erythropoiesis, as measured by the serum transferrin receptor concentration, increased from 12 to 120% of the basal value. This increment was not constantly associated with a proportional rise of Hb or reticulocyte count. SF decreased exponentially from a median value of 221 micrograms/dl (range 42-470) to a median value of 54 micrograms/dl (range 20-172). Halving of the basal SF value (SF-T50) was reached at the 18th-95th day of therapy (median = 43), representing a iron shift of 3.4-11.6 mg/day (median = 5.4). SF-T50 was not correlated with the Hb increase, but with that of erythropoiesis (r = 0.78; p = 0.003). The minimum SF (MSF) value attained was not correlated with the appearance of iron deficiency. The conclusion is that the rate of SF decrease during rHuEPO in ESRD is a reliable measure of iron mobilisation for erythropoiesis, but not for haematologic response. The MSF value reached during therapy is not representative of available iron for erythropoiesis.