Diagnostic accuracy and acceptability of molecular diagnosis of COVID-19 on saliva samples relative to nasopharyngeal swabs in tropical hospital and extra-hospital contexts: The COVISAL study.

A prospective study was conducted among different intra and extra-hospital populations of French Guiana to evaluate the performance of saliva testing compared to nasopharyngeal swabs. Persons aged 3 years and older with mild symptoms suggestive of COVID-19 and asymptomatic persons with a testing indication were prospectively enrolled. Nasopharyngeal and salivary samples were stored at 4°C before analysis. Both samples were analyzed with the same Real-time PCR amplification of E gene, N gene, and RdRp gene. Between July 22th and October 28th, 1159 persons were included, of which 1028 were analyzed. When only considering as positives those with 2 target genes with Ct values <35, the sensitivity of RT-PCR on saliva samples was 100% relative to nasopharyngeal samples. Specificity positive and negative predictive values were above 90%. Across a variety of cultures and socioeconomic conditions, saliva tests were generally much preferred to nasopharyngeal tests and persons seemed largely confident that they could self-sample. For positive patients defined as those with the amplification of 2 specific target genes with Ct values below 35, the sensitivity and specificity of RT-PCR on saliva samples was similar to nasopharyngeal samples despite the broad range of challenging circumstances in a tropical environment.

Noninvasive Diagnosis of Portal Hypertension in Patients With Compensated Advanced Chronic Liver Disease.

INTRODUCTION: We aimed to explore the prevalence of portal hypertension in the most common etiologies of patients with compensated advanced chronic liver disease (cACLD) and develop classification rules, based on liver stiffness measurement (LSM), that could be readily used to diagnose or exclude clinically significant portal hypertension (CSPH) in clinical practice. METHODS: This is an international cohort study including patients with paired LSM/hepatic venous pressure gradient (HVPG), LSM ≥10 kPa, and no previous decompensation. Portal hypertension was defined by an HVPG >5 mm Hg. A positive predictive value ≥90% was considered to validate LSM cutoffs for CSPH (HVPG ≥10 mm Hg), whereas a negative predictive value ≥90% ruled out CSPH. RESULTS: A total of 836 patients with hepatitis C (n = 358), nonalcoholic steatohepatitis (NASH, n = 248), alcohol use (n = 203), and hepatitis B (n = 27) were evaluated. Portal hypertension prevalence was >90% in all cACLD etiologies, except for patients with NASH (60.9%), being even lower in obese patients with NASH (53.3%); these lower prevalences of portal hypertension in patients with NASH were maintained across different strata of LSM values. LSM ≥25 kPa was the best cutoff to rule in CSPH in alcoholic liver disease, chronic hepatitis B, chronic hepatitis C, and nonobese patients with NASH, whereas in obese NASH patients, the positive predictive value was only 62.8%. A new model for patients with NASH (ANTICIPATE-NASH model) to predict CSPH considering body mass index, LSM, and platelet count was developed, and a nomogram was constructed. LSM ≤15 kPa plus platelets ≥150 × 10/L ruled out CSPH in most etiologies. DISCUSSION: Patients with cACLD of NASH etiology, especially obese patients with NASH, present lower prevalences of portal hypertension compared with other cACLD etiologies. LSM ≥25 kPa is sufficient to rule in CSPH in most etiologies, including nonobese patients with NASH, but not in obese patients with NASH.

Prospective Comparison of Saliva and Nasopharyngeal Swab Sampling for Mass Screening for COVID-19.

Current testing for COVID-19 relies on reverse-transcriptase polymerase chain reaction from a nasopharyngeal swab specimen. Saliva samples have advantages regarding ease and painlessness of collection, which does not require trained staff and may allow self-sampling. We enrolled 776 persons at various field-testing sites and collected nasopharyngeal and pooled saliva samples. One hundred sixty two had a positive COVID-19 RT-PCR, 61% were mildly symptomatic and 39% asymptomatic. The sensitivity of RT-PCR on saliva samples vs. nasopharygeal swabs varied depending on the patient groups considered or on Ct thresholds. There were 10 (6.2%) patients with a positive saliva sample and a negative nasopharyngeal swab, all of whom had Ct values <25 for three genes. For symptomatic patients for whom the interval between symptoms onset and sampling was <10 days sensitivity was 77% but when excluding persons with isolated N gene positivity (54/162), sensitivity was 90%. In asymptomatic patients, the sensitivity was only 24%. When we looked at patients with Cts <30, sensitivity was 83 or 88.9% when considering two genes. The relatively good performance for patients with low Cts suggests that Saliva testing could be a useful and acceptable tool to identify infectious persons in mass screening contexts, a strategically important task for contact tracing and isolation in the community.