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Daily Report

Daily Respiratory Research Analysis

07/29/2025
3 papers selected
3 analyzed

Three impactful respiratory papers stand out today: a high-quality Cochrane review confirms Xpert Ultra’s high accuracy for pulmonary tuberculosis and rifampicin resistance; a multicenter double-blind phase 2b RCT shows no clinical benefit of mesenchymal stromal cells in ARDS; and a nationwide modeling study quantifies substantial RSV-attributed adult mortality and hospitalizations in Denmark (2015–2024), informing vaccination strategy.

Summary

Three impactful respiratory papers stand out today: a high-quality Cochrane review confirms Xpert Ultra’s high accuracy for pulmonary tuberculosis and rifampicin resistance; a multicenter double-blind phase 2b RCT shows no clinical benefit of mesenchymal stromal cells in ARDS; and a nationwide modeling study quantifies substantial RSV-attributed adult mortality and hospitalizations in Denmark (2015–2024), informing vaccination strategy.

Research Themes

  • Molecular diagnostics for tuberculosis and drug resistance
  • Cell-based therapies in ARDS: efficacy and trial design
  • RSV burden modeling to guide adult vaccination and preparedness

Selected Articles

1. Xpert MTB/RIF Ultra assay for pulmonary tuberculosis and rifampicin resistance in adults and adolescents.

82.5Level ISystematic Review/Meta-analysis
The Cochrane database of systematic reviews · 2025PMID: 40728034

This Cochrane review of 32 studies (12,529 participants) confirms high accuracy of Xpert Ultra for detecting pulmonary TB (sensitivity 90.7%, specificity 94.8%) and robust performance for rifampicin resistance (sensitivity 95.8%, specificity 98.3%). Sensitivity decreases in smear-negative/culture-positive TB and in those with prior TB; trace-positive handling affects sensitivity–specificity trade-offs.

Impact: This synthesis underpins global diagnostic algorithms for TB and DR-TB, supporting rapid treatment initiation and programmatic scale-up of Ultra.

Clinical Implications: Use Xpert Ultra as the frontline NAAT for pulmonary TB and rifampicin resistance, with cautious interpretation of trace-positive results and awareness of reduced sensitivity in smear-negative and prior TB patients.

Key Findings

  • Pulmonary TB detection: pooled sensitivity 90.7% and specificity 94.8% vs. culture (32 studies; 12,529 participants).
  • Rifampicin resistance detection: sensitivity 95.8% and specificity 98.3% (10 studies; 1,644 participants).
  • Sensitivity drops in smear-negative/culture-positive TB (80.7%) and in those with prior TB; trace-positive results (true positive ~38.8%) affect performance trade-offs.
  • Low overall risk of bias; subgroup analyses by HIV, smear status, and TB history.

Methodological Strengths

  • Cochrane methodology with comprehensive search, QUADAS-2, and bivariate meta-analysis.
  • Large aggregate sample with prespecified subgroup analyses (HIV, smear status, TB history).

Limitations

  • Limited adolescent data (only six studies), constraining accuracy estimates in ages 10–14.
  • Heterogeneity in trace-positive handling and reference standards may affect pooled estimates.

Future Directions: Standardize trace-positive interpretation pathways, expand adolescent evaluations, and assess performance in prior TB and smear-negative populations with clinical outcome linkage.

BACKGROUND: Xpert MTB/RIF Ultra (Xpert Ultra) is a molecular World Health Organization (WHO)-recommended rapid diagnostic test that simultaneously detects tuberculosis and rifampicin resistance. This review updates a comparative accuracy Cochrane review of Xpert MTB/RIF and Xpert Ultra as Xpert Ultra has replaced Xpert MTB/RIF. OBJECTIVES: To determine the diagnostic accuracy of Xpert MTB/RIF Ultra (Xpert Ultra) for detecting pulmonary tuberculosis and rifampicin resistance in adults and adolescents with presumptive tuberculosis based on signs or symptoms or with an abnormal chest x-ray suggestive of tuberculosis. SEARCH METHODS: We searched seven databases including CENTRAL, MEDLINE, and Embase, plus two trial registers (ClinicalTrials.gov and the WHO ICTRP) to 16 October 2023 without language restrictions. A WHO Public Call for ongoing and unpublished studies was made between 30 November 2023 and 15 February 2024. SELECTION CRITERIA: We included cross-sectional studies, cohort studies, and randomised controlled trials that provided data on the diagnostic accuracy of Xpert Ultra using respiratory specimens in adolescents (aged 10 to 14 years) and adults (aged 15 years and older) with presumptive pulmonary tuberculosis. For pulmonary tuberculosis detection, the reference standards were culture and a composite reference standard. For rifampicin resistance, the reference standards were culture-based phenotypic drug susceptibility testing with or without whole genome sequencing. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data using a standardised form. We assessed risk of bias using QUADAS-2. We performed meta-analyses using a bivariate model to produce summary sensitivities and specificities, separately for pulmonary tuberculosis detection and rifampicin resistance detection. We performed subgroup analyses by smear status, HIV status, and history of tuberculosis. We summarised Xpert Ultra trace-positive results. MAIN RESULTS: Pulmonary tuberculosis detection For detection of pulmonary tuberculosis, Xpert Ultra summary sensitivity and specificity against culture were 90.7% (95% confidence interval (CI) 88.2 to 92.7) and 94.8% (95% CI 92.8 to 96.3) (32 studies, 12,529 participants; high-certainty evidence). Most studies had low risk of bias in all QUADAS-2 domains. If the point estimates for Xpert Ultra are applied to a hypothetical cohort of 1000 people, where 100 of those presenting with symptoms have pulmonary tuberculosis, Xpert Ultra will miss nine cases. The number of people wrongly diagnosed with pulmonary tuberculosis would be 47. In people living with HIV, Xpert Ultra summary sensitivity and specificity were 87.7% (82.0 to 91.7) and 95.3% (92.2 to 97.2) (11 studies, 1164 participants). Amongst people with smear-negative, culture-positive pulmonary tuberculosis, Xpert Ultra summary sensitivity and specificity were 80.7% (75.4 to 85.0) and 94.0% (91.3 to 95.9) (16 studies, 6460 participants). In people with a history of tuberculosis, Xpert Ultra summary sensitivity and specificity were 84.8% (78.2 to 89.7) and 86.2% (78.9 to 91.3) (9 studies, 809 participants). The proportion of Ultra trace-positive results that were true positives compared to the microbiological reference standard was 38.8%. Reclassifying trace-positive results as Xpert Ultra-negative led to a reduction in sensitivity and modest increase in specificity. Rifampicin resistance detection For detection of rifampicin resistance, Xpert Ultra summary sensitivity and specificity were 95.8% (93.2 to 97.4) and 98.3% (97.0 to 99.0) (10 studies, 1644 participants; high-certainty evidence). Most studies had low risk of bias in all QUADAS-2 domains. If the point estimates for Xpert Ultra are applied to a hypothetical cohort of 1000 people, where 100 of those presenting with symptoms have rifampicin resistance, Xpert Ultra will miss four cases. The number of people wrongly diagnosed with rifampicin resistance would be 16 out of the 900 who do not have rifampicin resistance. Xpert Ultra performed similarly, for rifampicin resistance, in people with smear-positive and smear-negative tuberculosis. AUTHORS' CONCLUSIONS: Xpert Ultra has high sensitivity and specificity for detection of pulmonary tuberculosis rifampicin resistance. Xpert Ultra for the detection of pulmonary tuberculosis has lower sensitivity in people with smear-negative/culture-positive tuberculosis and lower sensitivity and specificity in people with a history of tuberculosis. Xpert Ultra trace-positive results were common. Strengths of this review include the approach to identifying relevant studies, the number of studies and participants included in this systematic review, and that most studies were at low risk of bias. The small number of studies (six) and participants who were adolescents is a limitation to our accuracy estimates in this age group. Xpert Ultra testing provides accurate results and can allow rapid initiation of treatment for rifampicin-resistant and multiple-drug-resistant tuberculosis. FUNDING: The WHO supported this systematic review. Liverpool School of Tropical Medicine hosted the Cochrane Infectious Diseases Group (CIDG) editorial base, which supported the authors in the development of this review update. The Foreign, Commonwealth and Development Office funded the CIDG. REGISTRATION: Generic protocol available on Open Science Framework via https://osf.io/26wg7/wiki/home/. Previous protocol and review versions available via DOI 10.1002/14651858.CD009593 and DOI 10.1002/14651858.CD009593.pub5.

2. Treatment with Allogenic Mesenchymal Stromal Cells for Moderate to Severe Acute Respiratory Distress Syndrome: A Double-Blind, Placebo-controlled, Multi-Center, Phase 2b Clinical Trial (STAT).

78Level IIRCT
American journal of respiratory and critical care medicine · 2025PMID: 40728562

In this multicenter double-blind phase 2b RCT (n=120), a single IV dose of allogeneic MSCs did not improve oxygenation or mortality (14/28/60/180 days) in moderate–severe ARDS, including the COVID-19 subgroup. Exploratory biomarker analyses suggested differential responses in subgroups, motivating biomarker-enriched designs.

Impact: This well-designed negative RCT redirects the ARDS field away from empiric MSC use and toward precision, biomarker-guided trials.

Clinical Implications: Routine MSC therapy for ARDS should not be adopted based on current evidence; future trials should enrich for biomarker-defined phenotypes before broader implementation.

Key Findings

  • No improvement in the primary endpoint (36-hour change in oxygenation index) with single-dose MSCs vs. placebo.
  • No differences in mortality at 14, 28, 60, or 180 days in overall or COVID-19 ARDS cohorts.
  • Plasma protein and gene-expression biomarkers identified subgroups with differential clinical responses.

Methodological Strengths

  • Prospective, multicenter, double-blind, randomized design with appropriate controls.
  • Prespecified outcomes and extended mortality follow-up to 180 days; exploratory biomarker analyses.

Limitations

  • COVID-19 ARDS predominance (84%) may limit generalizability to non-COVID ARDS.
  • Single-dose regimen; potential underdosing or suboptimal timing not evaluated.

Future Directions: Design biomarker-enriched, phenotype-specific trials (e.g., endothelial injury, hyperinflammatory phenotypes) testing dose, timing, and repeat dosing; integrate mechanistic endpoints.

BACKGROUND: Prior clinical trials established the safety, but not the efficacy of bone marrow-derived mesenchymal stromal cells (MSCs) in the acute respiratory distress syndrome (ARDS). METHODS: We conducted a prospective, double-blind, multi-center randomized phase 2b clinical trial of one dose of intravenous MSCs (10 x 10 FINDINGS: Enrollment began in January 2020. Due to the Coronavirus 2019 (COVID-19) pandemic, the majority of subjects (101/120, 84%) developed ARDS from COVID-19. There were no significant baseline differences in severity of illness between patients treated with MSCs and those who received placebo in the entire cohort of 120 patients or in the 101 patients with COVID-19 ARDS. There was no difference in the primary endpoint of change in oxygenation index from baseline over 36 hours after study product administration for the entire cohort or the COVID-19 subgroup, nor were there significant differences in mortality at 14, 28, 60 or 180 days. Plasma protein biomarker and gene expression analyses identified sub-groups of patients with differential treatment responses in terms of clinical outcomes. INTERPRETATION: This phase 2b clinical trial identified no physiologic or clinical benefit from a single dose of MSCs in patients with ARDS, including those with COVID-19 ARDS. In future trials, baseline plasma biological markers may help identify patients who are more likely to benefit from MSCs therapy. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/). Clinical trial registration available at www. CLINICALTRIALS: gov, ID: NCT03818854.

3. Excess mortality and hospitalisations associated with respiratory syncytial virus, influenza, and COVID-19 among adults in Denmark (2015-2024): a modelling study.

68.5Level IIICohort
The Lancet regional health. Europe · 2025PMID: 40727239

Using national registers (2015–2024) and GAM time-series modeling, the study estimates substantial adult RSV-attributed mortality and admissions in Denmark, particularly in those ≥65 years (mortality 31.2/100,000; admissions 177.4/100,000), alongside influenza and COVID-19 burdens. Findings support prioritization of RSV immunization and capacity planning for older adults.

Impact: Provides robust, policy-relevant benchmarks for adult RSV burden in Europe, directly informing vaccine deployment and winter preparedness.

Clinical Implications: Health systems should plan RSV immunization and surge capacity for older adults; integrate RSV testing and surveillance with influenza/COVID-19 to guide timely interventions.

Key Findings

  • Estimated 3,944 RSV-, 5,675 influenza-, and 5,636 COVID-19-attributed deaths (2015–2024) in Denmark.
  • Among adults ≥65, annual mortality per 100,000: RSV 31.2, influenza 42.9, COVID-19 88.5; admissions per 100,000: RSV 177.4, influenza 164.6, COVID-19 398.7.
  • Recent increases in RSV-attributed outcomes likely reflect expanded testing post-pandemic.

Methodological Strengths

  • Nationwide linked registers with weekly resolution across nine years; GAM with negative binomial likelihood capturing seasonality and trends.
  • Variant-era differentiation and age-stratified burden estimates.

Limitations

  • Attribution relies on modeling assumptions and may be influenced by post-COVID testing intensity changes.
  • Generalizability beyond Denmark requires caution due to healthcare and surveillance differences.

Future Directions: Evaluate vaccine impact post-introduction using similar models; extend to comorbidity-specific risk, long-term outcomes, and cost-effectiveness in older adults.

BACKGROUND: Understanding the long-term epidemiology trends of RSV, influenza, and COVID-19 is essential for planning of vaccination strategies and healthcare system epidemic preparedness. This is the first study to provide a comprehensive estimation of both excess mortality and hospitalisations among adults for these respiratory viruses in a European setting. We aim to estimate excess mortality and excess hospitalisations for RSV, influenza, and COVID-19 among adults ≥18 years in Denmark from January 2015 to March 2024. METHODS: This nationwide time-trend modelling study investigates weekly mortality and hospitalisation rates surpassing the seasonal baseline for RSV, influenza, and COVID-19 among adults in Denmark. Data from the Cause of Death Register, the Danish National Patient Registry, and respiratory virus surveillance data were analysed with Generalized Additive Models (GAM) using a negative binomial likelihood function, including RSV, influenza, COVID-19 variants, and time effects to account for seasonality and trend. FINDINGS: We estimated 3944 RSV-attributed, 5675 influenza-attributed, and 5636 COVID-19-attributed deaths. Among adults aged 65 or older, the annual mortality rates were 31.2 per 100,000 for RSV, 42.9 for influenza, and 88.5 for COVID-19. Furthermore, we estimated annual admission rates for those aged 65 and older of 177.4 per 100,000 for RSV, 164.6 for influenza, and 398.7 for COVID-19. INTERPRETATION: This modelling study reveals a substantial impact of RSV on individuals aged 65 and older, with a notable increase in RSV-attributed deaths and hospitalisations in recent years likely due to expanded respiratory testing after the COVID-19 pandemic. Our findings highlight the need for increased awareness in previously considered lower-risk patients, and establish benchmarks for evaluating preventive interventions. FUNDING: This study received funding from Independent Research Fund Denmark.