Comparing outcomes and costs between contingent and combined first-trimester screening strategies for Down's syndrome

OBJECTIVE

To compare a contingent strategy with a combined strategy for prenatal detection of Down's syndrome (DS) in terms of cost, outcomes and safety.

STUDY DESIGN

The contingent strategy was based on a simulation, removing measurement of the free beta subunit of human chorionic gonadotropin (free βhCG) and calculating the DS risk retrospectively in 32,371 pregnant women who had been screened with the combined strategy in the first trimester. In the contingent strategy, a risk between 1:31 and 1:1000 in the first trimester indicated further testing in the second trimester (alpha-fetoprotein, inhibin A, unconjugated oestriol and free βhCG). The cut-off risk values for the contingent and combined strategies in the first trimester were 1:30 and 1:250, respectively, and the cut-off risk value for integrated screening in the second trimester was 1:250. Costs were compared in terms of avoided DS births, and the ratio of loss of healthy fetuses following invasive procedures per avoided DS birth was calculated.

RESULTS

The combined strategy had sensitivity of 40/44 (90.9%) and a false-positive rate of 2.8%. Corresponding values for the contingent strategy were 39/44 (88.6%) and 1.3%, respectively. Only 11% of pregnant women required tests in the second trimester, and the approximate cost reduction for each avoided DS birth was 5000€. The ratio of lost healthy fetuses following invasive procedures per avoided DS birth improved by up to 0.65.

CONCLUSION

The contingent strategy has similar effectiveness to the combined strategy, but has lower costs and fewer invasive procedures.

First trimester serum angiogenic/anti-angiogenic status in twin pregnancies: relationship with assisted reproduction technology

BACKGROUND

The risk of pre-eclampsia (PE) increases in twin pregnancies, especially when assisted reproduction technologies (ART) are used. The aim of this study was to assess angiogenic/anti-angiogenic factors in maternal serum in the first trimester of twin pregnancies and establish if the mode of conception influences angiogenic status.

METHODS

This prospective study enrolled women with twin (n = 61) and singleton (n = 50) pregnancies. Dichorionic twin pregnancies were divided into two groups according to their mode of conception. Singleton pregnancies were used as the control group. Soluble fms-like tyrosine kinase (sFlt-1), free placental growth factor (PlGF) and soluble endoglin (sEng) concentrations were measured in the first trimester maternal serum.

RESULTS

In the first trimester, women with twin pregnancies had higher serum concentrations of the anti-angiogenic factor sFlt-1 than that with singleton pregnancies (3924 ± 250 versus 2426 ± 162 pg/ml, respectively; P < 0.001). Maternal serum PlGF concentrations were lower in singleton pregnancies than those in twin pregnancies (37 ± 3.7 versus 59 ± 5.6, respectively; P < 0.001). Serum concentrations of sFlt-1 were higher in twin pregnancies conceived by ART than those in spontaneous twin pregnancies (4313 ± 389 versus 3522 ± 300 pg/ml, respectively; P < 0.05). No differences between groups were observed for sEng.

CONCLUSIONS

In the first trimester, twin pregnancies conceived using ART showed a heightened anti-angiogenic status that could explain the increased risk of PE in these cases.

Validation of the Beckman Coulter AcT 5 Diff Analyzer in a Reference Laboratory

At the Valle de Hebron Hospital's Central Laboratory, we have performed a study evaluating the performance, reliability, and practicability of the Beckman Coulter AcT 5 analyzer. The results observed with known controls showed within- and between-run imprecision of 1.05% to 6.97% for the basic hemogram parameters. With patient samples, the results were analogous, with within- and between-run imprecision of 1.33% to 5.98%. To complete the evaluation of the AcT 5 counter, we analyzed the influence of possible interfering factors such as the presence of jaundice, lipemia, hemolysis, platelet aggregates, and schistocytes on the results of the automated leukocyte differential as performed by the cell counter with the new chlorazol black stain. We studied the performance of the AcT 5 with regards to ease of use, speed, and cost. Finally, we evaluated the impact of introducing the AcT 5 counter into routine laboratory use as support to resolve problems raised with the Beckman Coulter GenS and LH-750 and the Bayer Advia 120 counters due to samples with interfering factors.

Apoptosis in Infectious Mononucleosis: Its Detection with the Beckman Coulter GenS Hematology Analyzer

This article describes the potential of the Beckman Coulter GenS hematology analyzer for detecting and quantifying the phenomenon of elevated apoptosis found during the incubation at 37 degrees C of samples containing CD45RO+ reactive T-lymphocytes from patients with infectious mononucleosis (IM). Visual detection was carried out with the GenS DF1 scattergram (volume/scatter), and the means and SDs of lymphocyte positional parameters (volume, scatter, and conductivity) were recorded from the instrument research screen before and after samples were incubated in an oven for 4 hours. Thirty-one IM samples were analyzed, and the results obtained after sample incubation showed a mean reduction in lymphocyte volume of 34%, a 3.9% increase in scatter, and a 4% increase in conductivity. A new cluster of cells consistent with apoptotic lymphocytes appeared in the GenS DF1 scattergram. May-Gr-Giemsa staining and extended manual counting of the samples carried out at the same time to validate and quantify the apoptosis of the analyzed samples detected a significant increase in apoptotic cells from 1.2% (range, 0%-3%) to 8.37% (range, 1%-39%) after incubation. The same process was used to evaluate a control group of patients, and the possible interference of platelet aggregation and erythroblasts (nucleated red blood cells) in GenS apoptosis quantification was investigated. The final results showed that the appearance of the apoptotic cluster in the GenS DF1 scattergram occurred in 96.8% of the IM cases, although this phenomenon is apparently nonspecific because similar clusters appear in other pathologies, such as viral infections (hepatitis, cytomegalovirus, and acquired immune deficiency syndrome). Additional quantitative studies of apoptosis kinetics indicated that at least 4 hours of incubation are necessary. This finding has directed an investigation of apoptosis-inducing drugs (camptothecin, theophylline) to reduce incubation time and thereby enhance the practical application of automated apoptosis detection in the diagnosis of IM and other diseases in which the phenomenon of apoptosis occurs.

Application of receiver operating characteristics curve (ROC) analysis when definitive and suspect morphologic flags appear in the new Coulter LH 750 analyzer

Workflow efficiency is important in every laboratory. Manual assessment of white blood cell counts and differentials that have been rejected by an automated analyzer is one of the most time-consuming tasks in the routine hematology laboratory. In this study, receiver operating characteristics (ROC) curve analysis was used for the first time when anomalous distribution and suspect flag alarms appeared in hemograms carried out with the new Beckman Coulter LH 750 analyzer. This article is our second about the LH 750 analyzer published in this journal; we increased the number of cases and describe the novel application of statistical analysis of ROC curves. In processing of specimens from patients with 3% to 6% immature granulocytes (myelocytes + metamyelocytes + bands ), the suspect flag Imm Ne 1 (immature granulocytes) showed 77% diagnostic efficiency with a maximum area under curve (AUC) of 0.71 and a 95% confidence interval (CI) of 0.597 to 0.831 without significant differences between the 3 available levels of alarms in the analyzer (L1, L2, L2). In processing of specimens from patients with >6% immature granulocytes, the Imm Ne 1 flag showed superior diagnostic efficiency of 98% with a maximum AUC of 0.80 and a CI of 0.713 to 0.879. The suspect flag Imm Ne 2 in processing of specimens from patients with >6% of immature granulocytes showed diagnostic efficiency of 92% with a maximum AUC of 0.77 and a CI of 0.665 to 0.871, finding a significant positive difference in level L3 regarding sensitivity in comparison with the other 2 levels of the analyzer (L1, L2). For specimens from patients with >2% blasts, the suspect Blasts alarm showed a diagnostic efficiency of 94%, an AUC of 0.91, and a CI of 0.775 to 1.043; positive differences were observed between the levels L2/L3 and L1. In processing of specimens with variant lymphocytes (large, granular, prolymphocytes, cleaved, chronic lymphocytic leukemia type, and so forth) >10% (x = 14%), the suspect alarm Var Lym (variant lymphocytes) showed a low diagnostic sensitivity of 20% with a maximum AUC of 0.59 and a CI of 0.300 to 0.870 without significant differences between the 3 available levels (L1, L2, L3). However, in processing of specimens presenting values >10% reactive or activated lymphocytes (x = 23%), typical for patients with infectious mononucleosis, the Var Lym flag showed a superior sensitivity of 75% with a diagnostic efficiency of 92% and an AUC of 0.84 with a CI of 0.587 to 1.089. Finally, the laboratory can easily program definitive abnormal morphological flags of distribution (granulocytosis, eosinophilia, monocytosis, and so forth) on the basis of its patient population. In this study we were able to carry out comparisons of AUC and to choose the values for the automated counts in percentage, absolute value, or both. Therefore we were able to define the reliability and impact on the alarm routine to optimize the performance of the user-adjustable definitive alarms for anomalous distribution.

Validation of the Coulter LH 750 in a hospital reference laboratory

Validation of the Coulter LH 750 was carried out in our central hospital laboratory, which processes 1500 hemograms per day for patients admitted into the 4 hospitals of our hospital complex and their corresponding outpatient departments. It is the reference laboratory for the provincial health care area. The analytical quality and the practical use of the instrument were studied, and we obtained within- and between-run imprecision estimates with reference controls of between 0.24% and 2.56% and inaccuracies of between -1.32% and 3.07% for basic hemogram parameters. Similar results were obtained with specimens from patients, with imprecision estimates between 0.56% and 2.56%. Linearity estimates were between 0.3 x 10(9)/L and 380 x 10(9)/L for leukocytes and between 3 x 10(9)/L and 1900 x 10(9)/L for platelets. The instrument evaluation was completed with a study of interference by bilirubin, lipemia, hemolysis, platelet clumps, and heparin and an examination of other variables, including carryover, detection limits, and the correlation of results with those of the Coulter Gen-S. A special evaluation was made of the new erythroblast count feature; with reference controls, imprecision estimates for this count were 10% to 12%, and with patient specimens imprecision averaged 10.39% up to 4 erythroblasts per 100 leukocytes. We also studied the correlation of LH 750 results and interferences with those of the manual reference method. Finally, National Committee for Clinical Laboratory Standards protocols were used to test for suspect and confirmation flags in leukocyte differential counts for 258 specimens representative of our routine. The practicability of the analyzer was studied in terms of technical difficulty, speed, and cost; also evaluated were new software elements for validation by source clinic and pathology and for reference values based on age. In conclusion, we analyzed the impact and improvements that may be expected in our laboratory (a user of Technicon and Coulter instruments) from introducing the new LH 750 analyzer into our routine.

Use of the Advia 120 hematology analyzer in the differential cytologic analysis of biological fluids (cerebrospinal, peritoneal, pleural, pericardial, synovial, and others)

The centralization of our laboratories and the demand for new parameters to measure have led to an increase in the number of biological fluid samples, which are generally sent for urgent analysis. Due to this they cannot be processed by manual methods. Meeting this increased demand for assistance is a challenge for the laboratory, and the challenge has been met by the automated hematology area. A study of the reliability of the Advia 120 hematology analyzer has been carried out through leukocyte and red blood cell counting of 179 biological fluids: cerebrospinal, peritoneal or ascitic, pleural, pericardial, synovial, and others. The automated leukocyte counts of cerebrospinal fluid samples containing up to 0.150 x 10(9) leukocytes/L are correlated with counts obtained with the manual reference method in a Neubauer counting chamber (r = 0.958; P = .0001). Applying Passing-Bablok regression analysis to these results indicates a slope p of 1.155 (95% confidence interval [CI], 0.915-1.347) and an ordinate intercept b of 0.0076 (95% CI, 0.012-0.034), showing the results to be perfectly interchangeable. In the comparison of the manual analysis of the leukocyte differential using the May-Grünwald-Giemsa staining method with the analysis using the automated method, the percentage of polymorphonuclear granulocytes of the Advia 120 basophil/lobularity method is significantly correlated (r = 0.844; P = .0001) with that obtained with the manual count. The results of Passing-Bablok regression analysis (p = 0.859 [95% CI, 0.58-1.190]; b = 8.8 [95% CI, -12.09-24.2]) indicate that these two counting methods are also perfectly interchangeable. Automated leukocyte and differential counts of peritoneal or ascitic fluids also show good correlations with the manual method, and the results are not statistically different. Pretreating synovial fluid samples with hyaluronidase enzyme allows their processing on the Advia 120; no significant differences were found between manual and automated methods with respect to leukocyte counts and differentials. Finally, results with pleural fluid samples indicated that leukocyte and differential counts obtained with the Advia 120 showed significant differences from results obtained with manual methods because of the high incidence of mesothelial, lymphoid, and other tumoral cells in this kind of fluid sample. This result shows that use of hematology analyzers is questionable for these kinds of samples, especially from oncology patients with tumors. A procedure is proposed for the processing of these pleural fluids.

[Lupus anticoagulant: complete automation (ACL-Futura) and diagnostic algorithm]

PURPOSE

The technical and clinical evaluation of a new laboratory profile with six tests, for the realization of the assay called "lupic anticoagulant" with the help of ACL-Futura analyzer (Intrumentation Laboratory).

RESULTS

The within-between day imprecision of the tests that compose the profile: APTT-Diluted, APTT-D Mix, LacScreen, LacScreen Mix, LacConfirm and LacConfirm Mix, are between 2.87%-11.61% with controls, this imprecision is lowest with patients. A study of bilirrubin and lipemia interferences is presented. The practicability study present the technical, time consuming difficulty, and shows that the cost of the screening test is about 1136 ptas (6.83 euros) and with the confirmative test is 2766 ptas (16.62 euros). The clinical study describes our preliminary results with the application of this new profile for almost 2 years and six clinical cases are presented.

CONCLUSIONS

The good technical and clinical results of the evaluation of the new profile proposed to detect the positive lupic anticoagulant, in addition to the fully automated assay with the ACL-Futura analyzer, validate the whole method to resolve the increased demand of these parameters.

Iron metabolism in burned children

The administration of iron supplementation in children with burns has been a subject of controversy. Recent studies argue against its use in the acute phase of stress. To assess whether iron metabolism parameters show significant differences in the acute phase and the recovery phase of burn, 21 patients (age range: 17 months to 13 years) with burns of more than 10% of body surface who had not received blood transfusions or iron supplementation were studied. Sideraemia, ferritin, transferrin, transferrin saturation index (TSI) and C-reactive protein (CRP) were assessed both in the acute and the recovery phase after burn. Sideraemia, transferrin, and TSI were significantly lower in the acute than in the recovery phase (17.3 +/- 3 vs 53.8 +/- 6.6 microg/dL, 190.5 +/- 15 vs 287.9 +/- 14.3 mg/dL and 7.7 +/- 1.3 vs 15.4 +/- 1.6%, P < 0.0001, P < 0.001 and P = 0.0006, respectively) while plasma ferritin and CRP were significantly higher (84.7 +/- 8.8 vs 43.1 +/- 8.5 ng/mL and 9.5 +/- 1.5 vs 0.7 +/- 0.2 mg/dL, P = 0.016 and P < 0.0001, respectively). When the above parameters were analysed based on age (< or = 2 years, > 2 years), the observed differences persisted.

CONCLUSION

Hyposideraemia is a frequent finding in the acute phase of paediatric burns and is accompanied by increased ferritin levels and decreased transferrin concentrations. The low iron values tend to recover without the use of iron supplementation suggesting an endogenous block of iron release in the acute phase and indicates that iron therapy should be not recommended in the initial period of stress of the burned patient.

Evaluation of the Menarini-Arkray HA 8140 hemoglobin A1c analyzer

We describe a multinational evaluation of the Menarini-Arkray HA 8140 hemoglobin (Hb) A1c analyzer, which utilizes a high degree of automation, including bar code reading, cap piercing, and whole-blood sampling. With-in- and between-batch CVs were < 2%. Linearity was confirmed throughout the working range of the analyzer. Common Hb variants, including Hb S, Hb C, and Hb F, did not interfere with the Hb A1c separation, and the potentially interfering labile Schiff base was effectively removed during the chromatographic procedure. The HA 8140 analyzer displayed good correlation to the Bio-Rad Variant analyzer, Tinaquant immunoassay, affinity chromatography, and an optimized "in-house" HPLC Hb A1c method. The methods when compared by Altman and Bland plots showed bias (upper, lower 95% confidence limits) of: Variant minus HA 8140 = 0.99 (0.23, 1.74), Tinaquant minus HA 8140 = 0.14 (-0.71, 0.98); affinity minus HA 8140 (after log transformation) = 1.13 (0.90, 1.41), and "in house" HPLC minus HA 8140 (after log transformation) = 0.91 (0.82, 1.01).

[Initial evaluation of the ACL-Futura coagulation analyzer]

PURPOSE

The first analytical performance of analyzer ACL-Futura (Instruments Laboratory) is presented.

RESULTS

The analyzer shows an within-between day imprecision with controls, for PT (prothrombin time) of 0.7-8%, APTT (activated partial thromboplastin time) of 0.7-4%, fibrinogen (derived) 2-6%, ATIII (antithrombin III) of 3-9%, with specimens the imprecision is lowest. The linearity and carry-over for all the techniques were studied. An study of medicine interferences (Aspirin and Sintrom) and bilirubin, lipemia was performed. The reference values are presented. We study the practicability of the analyzer: technical difficulty, time consuming, determination cost and the usefulness in the urgency laboratory.

CONCLUSION

These results validate the method to resolve the increased demand of these parameters.

[First evaluation of the Variant haemoglobin analyzer (Bio-Rad)]

PURPOSE

The analytical performance of the first automated HPLC analyzer of haemoglobins A2 and Foetal is presented.

RESULTS

The analyzer shows an imprecision within-run between 0.66-2.7% and between-run 1.8-6.44. Correlation index with manual methods were r = 0.965 (p < 0.005) for Hb A2 and r = 0.999 (p < 0.0001) for Foetal Hb and the reference values of an adult population were established; Hb A2 (1.98-2.94%) and Hb F (0-0.95%). Several chromatograms of haemoglobinopathies are presented.

CONCLUSIONS

These results validate the method to resolve the increased demand of these parameters.

[Reference values for vitamin B12 in blood in a population of children and one of adults using the IMxRB12 method]

In this study we have performed the reference values of vitamin B12 of a population of 124 children aged 0-18 years and 42 adults aged 19-55 years, assessed by the recent method IMxR B12. Abbott. The population studied included outpatients, some inpatients and groups of subjects undergoing banal examinations in the Hospital Universitario Materno-Infantil of Barcelona.

STATISTICS

Data were first tested for goodness-of-fit gaussian distribution by a nonparametric test, by testing skewness and kurtosis coefficients for significance and by Kolmogorov-Smirnov test. The correlation with the age groups was evaluated with Student's-t-test.

RESULTS

We show the histograms of the data obtained and a nonparametric approach selecting the central 95th percentile range. Reference limits (5-95th percentile range) were as follows: Premature infants = 365-1568 ng/L; 1-3 years = 345-1154 ng/L; 4-6 years = 330-1236 ng/L; 7-11 years = 312-1237 ng/L; 12-18 years = 328-1185 ng/L; Adults (19-55 years) = 300-964 ng/L. There were no significant differences between both sexes. The goodness-of-fit test for a gaussian distribution showed no departure from normality except for the groups of children 12-18 years old. A simple linear regression analysis showed that age significantly affected the concentration in inverse way.

CONCLUSIONS

The importance of establishing the reference values of vitamin B12 lies in the relevance of this serum analyte to some pathophysiological conditions. Considerable racial heterogeneity exists in populations, and these racial differences profoundly affect total values of vitamin B12 so that different racial reference limits have been suggested.

Specific IgE antibodies in nasal secretions: correlation with serum values and clinical tests

The presence of specific IgE in external secretions and the possibility of quantifying it has aroused the interest of many research workers. Nevertheless, there is still disagreement with regard to how useful this practice is from a clinical point of view. We have compared the presence of Dermatophagoides pteronyssinus (Dp) specific-IgE in the nasal secretion of 17 patients suffering from rhinitis with the results of prick tests and nasal and/or conjunctival challenge tests. As a preliminary step we have updated techniques and made a correlation between the parameters mentioned. The results for total IgE (n = 17) show a correlation coefficient (r = .39, NS) between serum values (251 +/- 239) U/L and those obtained in nasal secretion (28 +/- 36) U/L. (2) Serum and nasal-Dp-specific-IgE values (13 +/- 15 and 5 +/- 9, respectively: (r = .72, P = .0011) match in 14 of the 17 determinations. In two of them, the serum values of Dp-specific-IgE, but not the nasal ones, match the in vivo tests. In the others, it is the nasal secretion determination that matches the in vivo tests while the serum and nasal determinations match (82%). These results match in 86% of cases with prick tests and in 93% with nasal/conjunctival challenge tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Reagent strip for semiquantitative total and specific IgE measurement: a comparison to radioisotopic methods

Determination of total and specific IgE using reactive test strips may afford a useful screening method in the in vitro diagnosis of allergens owing to easy use and possible correlation with established methods. T.D. LETI reactive strips for the semiquantitative determination of total IgE is a method combining classical fundamentals (sandwich anti-IgE-IgE-labeled anti-IgE) and the use of strip methods. It also permits determination of specific IgE levels in a wide range of Mediterranean and food (10) allergens. In a preliminary assessment, this method was correlated with isotopic PRIST for total IgE and with Phadebas RAST for specific IgE. The most important features are: a) no additional equipment besides serum or whole blood; b) cheaper and faster than PRIST for total IgE; c) correlation coefficient of 0.88 in the proposed range (n = 20) and 0.91 (n = 25) in the 10-500 U/ml range for PRIST/T.D. LETI for total IgE; d) specific IgE determination strips present sensitivity and specificity of 88 and 91%, respectively, in 180 allergens assayed in relation to Phadebas RAST. In conclusion, the in vitro diagnosis of allergens using reactive strips is currently a practical and simple method. By optimizing the top of the scale for total IgE and reducing the volume and/or time in specific IgE, it may prove to be an important screening method.

Acetyl salicylic acid induced-urticaria and/or angioedema in atopic children

From the report of Hirschberg, only 3 years after aspirin synthesis, there have been numerous works dedicated to showing the different types of adverse reactions found following aspirin administration. However, there are few publications on the process of urticaria and/or acute angioedema induced by ASA and few reported cases were found in children. Thus, we present 6 atopic children with urticaria and/or angioedema related with ASA. A carefully detailed history, oral provocation with ASA, oral provocation with other NSAI and HBDT with ASA were done to all of them. The oral provocation with ASA was positive in 5 of the 6 cases. The provocations with the rest of the NSAI and tartrazine and sodium benzoate were negative in all of the patients. The HBDT was positive in 5 of the cases. In conclusion, we insist that aspirin intolerance is not infrequent in infancy and it is not rare to see urticaria and or angioedema, in spite of the fact that asthmatics, atopics or non atopics, usually present as bronchospasm. We also believe that the HBDT can be a method of diagnosis used in these cases.

Penicillin allergy: in vivo and in vitro diagnostic methods

Hypersensitivity to beta lactams, especially that mediated by IgE or IgG4, is the most frequent complaint of adverse drug reactions. There are multiple studies dedicated at establishing a method that can permit us to arrive at an accurate diagnosis, but from these studies one deduces that the difficulty lies in the lack of a test with a 100% reliability. In the present study we evaluate the correlation between the different methods. For this we selected 16 children, composed of 8 males and 8 females, whose ages ranged between 2 years 7 months and 9 years 8 months, and who had a reaction to penicillin G via parenteral. The following tests were done on them: Skin tests with a major determinant antigen (constant composition and molecular weight), with minor determinants. Human basophil degranulation test (modified Leynadier technique). Mathov's progressive controlled provocation test, which we considered the most reliable. Only in eight cases a diagnosis of penicillin allergy was arrived at. The correlation between the different tests were: Mathov - HBDT 93.75%; Mathov - PPL 93.75% and PPL - HBDT 87.5%.

Intralipid and free plasmatic tryptophan in vitro

In an attempt to investigate the role of the lipidic emulsion Intralipid in the development of metabolic encephalopathy in a patient showing high free tryptophan levels, the relationship between lipidic emulsion and free tryptophan was examined in in vitro experiments. The addition of intralipid to normal serum produces an immediate increase in non-esterified fatty acids and a parallel rise in free tryptophan. Moreover, when serum with intralipid is incubated at 37 degrees C, the lipases release new non-esterified fatty acids and the free tryptophan increases proportionally. The non-esterified fatty acid content of intralipid was found to be 12 +/- 2 mEq X 1(-1). An inverse correlation was seen between free tryptophan and different serum albumin concentrations. It is concluded that intralipid causes an increase in free tryptophan levels. It is known that in vivo free tryptophan modulates 5-hydroxytryptamine synthesis and thus may be considered a possible causal agent for encephalopathy.