Potential for a large-scale newborn screening strategy for sickle cell disease in Mali: A comparative diagnostic performance study of two rapid diagnostic tests (SickleScan® and HemotypeSC®) on cord blood

Sickle cell disease (SCD) is a life-threatening disease requiring reliable early diagnosis. We assessed the acceptability and diagnostic performances of two rapid diagnostic tests (RDTs) to identify SCD (HbSS, HbSC, HbS/β-thalassaemia) or SCD carrier (HbS/HbC) in a pilot SCD newborn screening (NBS) strategy in Mali. All consenting delivering women were offered SCD NBS using cord blood sampling on two RDTs (SickleScan® and HemotypeSC®) compared to the high-performance liquid chromatography (HPLC) gold standard to detect SCD states. From April 2021 to August 2021, 4333 delivering women were eligible of whom 96.1% were offered NBS: 1.6% refused, 13.8% delivered before consenting and 84.6% consented; 3648 newborns were diagnosed by HPLC; 1.64% had SCD (0.63% HbSS, 0.85% HbSC, 0.16 HbS/β-plus-thalassaemia); 21.79% were SCD carrier. To detect accurately SCD, SickleScan® had a sensitivity of 81.67% (95% confidence interval [CI]: 71.88-91.46) and a negative predictive value (NPV) of 99.69% (95% CI: 99.51-99.87); HemotypeSC® had a sensitivity of 78.33% (95% CI: 67.91-88.76) and a NPV of 99.64% (95% CI: 99.44-99.83). To detect SCD carrier: SickleScan® sensitivity was 96.10% (95% CI: 94.75-97.45) and NPV, 98.90% (95% CI: 98.51-99.29); HemotypeSC® sensitivity was 95.22% (95% CI: 93.74-96.70) and NPV, 98.66% (95% CI: 98.24-99.03). Routine SCD NBS was acceptable. Compared with HPLC, both RDTs had reliable diagnostic performances to exclude SCD-free newborns and to identify SCD carriers to be further confirmed. This strategy could be implemented in large-scale NBS programmes.

Ultrasound assessment is linked to histological vein wall thickness in chronic venous disease

OBJECTIVES

Few studies compared both ultrasound and histological approaches for the same series of patients with chronic venous disease (CVD). We aimed to assess the diagnostic performances of duplex ultrasound assessment (US) of Vein Wall Thickness (VWT) among patients with CVD.

METHODS

38 adults with primary varicose veins having undergone Great Saphenous Vein thermal ablation with phlebectomy, and agreeing to biopsy of the Posterior Accessory Great Saphenous Vein (PASV) were consecutively included in a two-center prospective study. VWT assessment of the PASV was performed using both US, and microscope examination. High values for microscope-assessed VWT were defined at > 0.5 mm.

RESULTS

The mean age was 53.0 ± 13.1 years, 71% were women. Maximization of US performances was obtained with a threshold of 0.6 mm: Sensitivity (Se) = 92.9%, Specificity (Sp) = 91.7%, positive (86.7%) and negative predictive value (NPV) (95.7%), positive (11.1) and negative likelihood ratio (NLR) (0.07).

CONCLUSIONS

US assessment of VWT could be a non-invasive tool for diagnosis and follow-up in CVD, and an interesting in vivo parameter complementing diameter and reflux measures, with a view to optimizing treatment. It could help to determine i) the energy level necessary in case of endovenous laser ablation, and ii) the sclerosing agent concentration in case of chemical ablation.

Diagnostic performances of Exacto® Triplex rapid test for diagnosis of HIV/HCV/HBsAg: a multicenter, cross-sectional, field study in the Central African Republic

INTRODUCTION

the Exacto® Triplex HIV/HCV/HBsAg (Biosynex, Strasbourg, France) consists in lateral flow, immunochromatographic rapid diagnostic test simultaneously detecting human immunodeficiency virus (HIV)-1 and HIV-2 and hepatitis C virus (HCV)- specific antibodies (IgG and IgM) and hepatitis B virus (HBV) surface antigen (HBsAg) in serum, plasma and whole blood. We herein evaluated its diagnostic performances in the Central African Republic (CAR).

METHODS

cross-sectional study was conducted on prospectively collected panel of 550 sera from adult inpatients living in Bangui, including 200 HIV-positive, 100 HBsAg-positive, 50 HCV-positive, 200 negatives to three viruses according to reference immuno-enzymatic serological tests including Murex HCV (Diasorin, Saluggia, Italy) for HCV, Murex HBsAg (Diasorin) for HBV, Genscreen ULTRA HIV Ag-Ab HIV-1/2 Version 2 (Bio-Rad, Marnes-la-Coquette, France) and Murex HIV 1.2.0 Ag/Ab Combination (Diasorin), the 2 tests associated in the parallel algorithm for the reference strategy for the diagnosis of HIV in CAR. Serum samples were tested blindly in duplicate. The findings are reported following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.

RESULTS

the Exacto® Triplex showed 99.5% (95% CI; 98.5-100.0), 96.0% [90.6-100.0] and 99.0% [97.1-100.0] sensitivities for HIV, HCV and HBsAg, respectively. The specificity, positive and negative predictive values (PPV and NPV) were 100.0% for all three viruses. The Youden's J index and Cohen's κ coefficient were 0.99 for HIV and HBsAg. For HCV, Youden's J and Cohen's κ coefficient were 0.96 and 0.98, respectively. In the epidemiological context of the CAR, the PPV and NPV for all three viral infections were high (≥99.0% to 100%).

CONCLUSION

taken together, our STROBE-compliant study demonstrates that the Exacto® Triplex HIV/HCV/HBsAg showed high sensitivity and specificity for HIV and HBsAg (≥99.0%), and relatively high sensitivity (96.0%) and high specificity (100%) for HCV. These analytical performances are within the limits required by the WHO (i.e. sensitivity ≥99.0% and specificity ≥98.0%) for HIV and HBV. The Exacto® Triplex HIV/HCV/HBsAg is user-friendly at low cost, and appears highly desirable for routine use in the CAR, and likely other Central African countries.

High Performance of SARS-Cov-2N Protein Antigen Chemiluminescence Immunoassay as Frontline Testing for Acute Phase COVID-19 Diagnosis: A Retrospective Cohort Study

Objectives: COVID-19 emerged and rapidly spread throughout the world. Testing strategies focussing on patients with COVID-19 require assays that are high-throughput, low-risk of infection, and with small sample volumes. Antigen surveillance can be used to identify exposure to pathogens and measure acute infections. Methods: A total of 914 serum samples, collected from 309 currently infected COVID-19 patients, 48 recovered ones, and 410 non-COVID-19 patients, were used to measure N protein antigen levels by a chemilumineseent immunoassay. Diagnostic performances were analyzed in different periods after onset. Results: There was a high level of N protein antigen in COVID-19 patients (0.56 COI), comparing to the recovered patients (0.12 COI) and controls (0.19 COI). In receiver-operating characteristic curve analysis, the area under the curve of serum N protein antigen was 0.911 in the first week after onset. In this period, Sensitivity and specificity of serologic N protein antigen testing was 76.27 and 98.78%. Diagnosis performance of specific antibodies became better from the third week after onset. Subgroup analysis suggested that severe patients had higher levels of antigens than mild patients. Conclusions: High level of serum antigen suggested early infection and serious illness. Serum N protein antigen testing by chemiluminescence immunoassay is considered as a viable assay used to improve diagnostic sensitivity for current patients.

Ultrasound screening for fetal anomalies in a single center: diagnostic performances twenty years after the Eurofetus Study

PURPOSE

To establish the accuracy of ultrasound in detecting fetal anomalies looking at the concordance between prenatal and postnatal diagnosis.

MATERIALS AND METHODS

Retrospective analysis of concordance between prenatal and postnatal/autoptic diagnosis of fetuses with congenital abnormalities. Data are from a single center (Policlinico di Modena); all fetuses included were born between 2017 and 2018 and with a follow-up of at least 6 months. We included all deliveries (including perinatal deaths) and termination of pregnancy (TOP) for fetal indication. We calculated sensibility, sensitivity, Positive and Negative Likelihood Ratio, positive and negative predictive value of ultrasound.

RESULTS

During the study period 5920 deliveries, including perinatal deaths, and 28 TOP for fetal indication were registered at our center. The prevalence of congenital malformations was 2.6% (153/5920). At least one ultrasound was performed in our center in 1250 women delivering in our unit. All 28 TOP had the anomaly scan performed in our center. Among the total 1278 women scanned in our unit, there were 128 (10%) suspicious scans. In 5/128 (3.9%) cases we diagnosed a false alarm; in 8/128 (6.2%) cases an evolutive malformation with in-utero regression. The prenatal diagnosis was confirmed in 77 (60.2%) cases at birth and in 28/128 (21.9%) at postmortem analysis while there were 10/128 false positive (7.8%). Among the 153 congenital malformations diagnosed at birth, the anomaly scan was performed in our Prenatal Medicine Unit in 92 (60.1%) fetuses. Among these, there were 15 false negatives (9.8%) while in 77/92 (83.7%) the malformation at birth agreed with the sonographic diagnosis. Sensitivity and specificity of ultrasound were 87.5% (IC95 80.2-92.8%) and 99.1% (IC95 98.4-99.6%) respectively with a Positive Likelihood Ratio and Negative Likelihood Ratio of 101.3 (IC95 54.5-188.5) and 0.13 (IC95 0.08-0.2); Positive Predictive Value and Negative Predictive Value were 91.3% (IC95 85-95.1%) and 98.7(IC95 98-99.2%).

CONCLUSION

Anomaly scan in pregnancy allows the diagnosis of congenital malformations with a sensibility of 87.5% and specificity of 99.1%. The main limitations of this study are its retrospective design and that it was conducted in a single referral center.