Performance of six rapid diagnostic tests for SARS-CoV-2 antigen detection and implications for practical use

Background

Direct detection of SARS-CoV-2 viral proteins in nasopharyngeal swabs using lateral flow immunoassays is a simple, fast and cheap approach to diagnose the infection.

Aims and Methods

The performance of 6 SARS-CoV-2 antigen rapid diagnostic tests has been assessed in 634 hospitalized patients or outpatients including 297 patients found to be positive for SARS-CoV-2 RNA by means of RT-PCR and 337 patients presumed to be SARS-CoV-2 RNA-negative.

Results

The specificity of SARS-CoV-2 RDTs was generally high (398.5%). One assay had a lower specificity of 93.2%. The overall sensitivity of the 6 RDTs was variable, from 32.3% to 61.7%. Sensitivity correlated with the delay of sampling after the onset of symptoms and the viral load estimated by the Ct value in RT-PCR. Four out of 6 RDTs tested achieved sensitivities 380% when clinical specimens were collected during the first 3 days following symptom onset or with a Ct value ≤25.

Conclusions

The present study shows that SARS-CoV-2 antigen can be easily and reliably detected by RDTs. These tests are easy and rapid to perform. However, the specificity and sensitivity of COVID-19 antigen RDTs may widely vary across different tests and must therefore be carefully evaluated before releasing these assays for realworld applications.

Economic burden of preemptive treatment of CMV infection after allogeneic stem cell transplantation: a retrospective study of 208 consecutive patients

BACKGROUND

Cytomegalovirus (CMV) infection and disease (CMV episodes) are global concerns after allogeneic hematopoietic stem cell transplantation (HSCT). They affect survival, both by direct and indirect effects. Due to safety issues of current anti-CMV antivirals, long-term CMV prophylaxis is poorly tolerated and the most common strategy to decrease the incidence of CMV disease is preemptive. New, less toxic, molecules are currently being assessed for CMV prophylaxis which should replace or considerably decrease the preemptive approach. The aim of this study was to assess the economic burden of CMV episodes after HSCT with a preemptive approach.

METHODS

We analyzed data from 208 consecutive adults transplanted in our institution, between 2008 and 2013. Hospital resource utilization was retrieved via the linked hospital admissions and Diagnostic Related Groups for the period of conditioning to 12 months after transplant.

RESULTS

CMV episodes occurred in 70 patients (34%) over the first 12 months following HSCT, after a mean of 75 days (median: 46 (7-334)). The mean total length of stay was significantly associated with the occurrence of a CMV episode (113.9 vs. 87.5 days, p = 0.0002) but was associated neither with the pre-transplant CMV serology of donors/recipients nor with survival. The mean cost of transplant was €104,016 (SD = €37,281) after 12 months. Bivariate and multivariate analyses indicated that the occurrence of >1 CMV episode increased the costs of allogeneic HSCT by 25-30% (p < 0.0001).

CONCLUSION

Our study, which is the largest, single-institution cost study of allogeneic HSCT in Europe, shows that two or more CMV episodes significantly increased the transplant cost. New prophylactic strategies to prevent CMV infection and disease should decrease transplant costs.

Risk stratification of early admission to the intensive care unit of patients with no major criteria of severe community-acquired pneumonia: development of an international prediction rule

Introduction

To identify risk factors for early (< three days) intensive care unit (ICU) admission of patients hospitalised with community-acquired pneumonia (CAP) and not requiring immediate ICU admission, and to stratify the risk of ICU admission on days 1 to 3.

Methods

Using the original data from four North American and European prospective multicentre cohort studies of patients with CAP, we derived and validated a prediction rule for ICU admission on days 1 to 3 of emergency department (ED) presentation, for patients presenting with no obvious reason for immediate ICU admission (not requiring immediate respiratory or circulatory support).

Results

A total of 6560 patients were included (4593 and 1967 in the derivation and validation cohort, respectively), 303 (4.6%) of whom were admitted to an ICU on days 1 to 3. The Risk of Early Admission to ICU index (REA-ICU index) comprised 11 criteria independently associated with ICU admission: male gender, age younger than 80 years, comorbid conditions, respiratory rate of 30 breaths/minute or higher, heart rate of 125 beats/minute or higher, multilobar infiltrate or pleural effusion, white blood cell count less than 3 or 20 G/L or above, hypoxaemia (oxygen saturation < 90% or arterial partial pressure of oxygen (PaO₂) < 60 mmHg), blood urea nitrogen of 11 mmol/L or higher, pH less than 7.35 and sodium less than 130 mEq/L. The REA-ICU index stratified patients into four risk classes with a risk of ICU admission on days 1 to 3 ranging from 0.7 to 31%. The area under the curve was 0.81 (95% confidence interval (CI) = 0.78 to 0.83) in the overall population.

Conclusions

The REA-ICU index accurately stratifies the risk of ICU admission on days 1 to 3 for patients presenting to the ED with CAP and no obvious indication for immediate ICU admission and therefore may assist orientation decisions.

Impact of point-of-care testing in the emergency department evaluation and treatment of patients with suspected acute coronary syndromes

OBJECTIVES

To assess the impact of point-of-care testing (POCT) for troponin I (cTnI) measurement on the time to anti-ischemic therapy (TAIT) for patients with suspected non-ST-segment elevation acute coronary syndrome (NSTE-ACS) presenting to the emergency department (ED).

METHODS

This was an open-label, randomized, single-center trial conducted in a university-affiliated hospital. cTnI measurement of patients with suspicion of NSTE-ACS coming to the ED was randomly allocated to POCT or central hospital laboratory testing (CHLT). The authors compared patients' baseline characteristics, time to anti-ischemic therapy, and medical outcomes between the randomized groups, in all study participants and in high-risk NSTE-ACS (cTnI level >or= 0.10 microg/mL), and in those with low suspicion ACS (no chest pain and no ST deviation).

RESULTS

Of the 860 patients enrolled, 113 were high-risk NSTE-ACS patients, including 53 (46.9%) allocated to POCT and 60 (53.1%) to CHLT. POCT was associated with decreased time to anti-ischemic therapy of about three-quarters of an hour, which was due to a shorter time to physician notification of cTnI level, in both all and subgroup participants. In contrast, neither ED length of stay nor medical outcomes differed between study groups.

CONCLUSIONS

Point-of-care testing for cTnI measurement might be clinically relevant for ED patients with a suspicion of NSTE-ACS, particularly for high-risk patients with a low suspicion of ACS.

[ICU performance: results of a French study involving 80,000 ICU stays]

OBJECTIVE

The Standard Mortality Ratio (SMR), comparing the observed in-hospital mortality to the predicted, may measure the intensive care units (ICU) performance.

STUDY DESIGN

Multicentric retrospective national study.

METHODS

A probability model using a severity score such SAPS II calculated the predicted mortality rate. A national French study has been undertaken to compare the SMR of ICUs and looked for explanation.

RESULTS

One hundred six units, 34 were medical (32%), 18 surgical (17%) and 57 medical/surgical (51%) participated to the study. Forty-six ICUs (43%) were located in teaching hospitals. The SMR of the 87,099 stays was 0.84 (0.82-0.85). The SMR of ICUs varied from 0.41 to 1.55. Ten units had a SMR>0.85, which suggested a low performance. They had more stays for cardiovascular failures, as compared with others. The best units (SMR<0.82) had more stays for drug overdose. The SMR increased with the number of organ failures, from 0.47 with zero failure to 1.11 with 4 or more organ failures. The stays with cardiovascular failure, either unique or associated, had a higher SMR. The 7935 stays with a drug overdose had a SMR of 0.12 (0.10-0.14), which suggested a bad calibration of the model in theses cases.

CONCLUSION

The case mix must be taken in account when comparing the ICUs performance by the mean of SMR, particularly when the units admitted a lot of drug overdoses.

[Completeness of ICU activity reports sent to French healthcare authorities]

INTRODUCTION

Hospital units report on their inpatient care activity by writing yearly activity reports, which are used by their Medical Information Department (MID) to develop standardized summaries for communication to healthcare authorities. The data are categorized by uniform patient groups and used to describe inpatient care activity and to guide resource allocation. The objective of this study was to evaluate the completeness of activity reports from intensive care units (ICUs) in France.

METHODS

Activity reports sent in 1998 and 1999 by French ICUs participating in the study were collected using dedicated abstracting software supplied to the relevant MIDs. Completeness of data in the activity reports was evaluated, with special attention to the SAPSII score, Omega rating of ICU procedures according to the Classification of Medical Procedures, and primary and secondary diagnoses.

RESULTS

The 106 ICUs that volunteered for the study reported data on 107,652-hospital stays. Mean age and SAPSII were 55 +/- 21 years and 35 +/- 21 years, respectively. Mean ICU and hospital lengths of stay were 6.2 +/- 12.4 and 16.1 +/- 21.6 days, respectively. Mean ICU and hospital mortality rates were 15% and 19%. The SAPSII and Omega procedures were reported for 81% and 80% of stays, respectively. The SAPSII and Omega procedures were calculated or coded in 94% (100/106) and 96% (102/106) of ICUs, respectively. Mean number of Omega procedures was 4.3+/-3.9. However, only 5% (5/106) of ICUs entered the SAPSII for every stay, and 21% (22/106) of ICUs failed to enter the SAPSII for over 20% of stays. Similarly, 53% (56/106) of ICUs rated no more than five Omega procedures on average per stay. The primary diagnosis was reported for all stays, and the mean number of secondary diagnoses was 3.5 +/- 3.8. In 80% (86/106) of ICUs, no more than five secondary diagnoses were coded on average per stay.

CONCLUSION

The analysis of this national database shows that data communicated to the MIDs and therefore to the healthcare authorities, are incomplete regarding SAPSII, ICU procedures, treatment intensity, and diagnoses. This may lead to the underestimation of ICU activity and resource needs, particularly if the SAPSII and selected procedures identified as markers for high-intensity critical care are used in the future.