Effect of convalescent blood products for patients with severe acute respiratory infections of viral etiology: A systematic review and meta-analysis

Problematic meta-analyses: Bayesian and frequentist perspectives on combining randomized controlled trials and non-randomized studies

PURPOSE

In the literature, the propriety of the meta-analytic treatment-effect produced by combining randomized controlled trials (RCT) and non-randomized studies (NRS) is questioned, given the inherent confounding in NRS that may bias the meta-analysis. The current study compared an implicitly principled pooled Bayesian meta-analytic treatment-effect with that of frequentist pooling of RCT and NRS to determine how well each approach handled the NRS bias.

MATERIALS & METHODS

Binary outcome Critical-Care meta-analyses, reflecting the importance of such outcomes in Critical-Care practice, combining RCT and NRS were identified electronically. Bayesian pooled treatment-effect and 95% credible-intervals (BCrI), posterior model probabilities indicating model plausibility and Bayes-factors (BF) were estimated using an informative heavy-tailed heterogeneity prior (half-Cauchy). Preference for pooling of RCT and NRS was indicated for Bayes-factors > 3 or < 0.333 for the converse. All pooled frequentist treatment-effects and 95% confidence intervals (FCI) were re-estimated using the popular DerSimonian-Laird (DSL) random effects model.

RESULTS

Fifty meta-analyses were identified (2009-2021), reporting pooled estimates in 44; 29 were pharmaceutical-therapeutic and 21 were non-pharmaceutical therapeutic. Re-computed pooled DSL FCI excluded the null (OR or RR = 1) in 86% (43/50). In 18 meta-analyses there was an agreement between FCI and BCrI in excluding the null. In 23 meta-analyses where FCI excluded the null, BCrI embraced the null. BF supported a pooled model in 27 meta-analyses and separate models in 4. The highest density of the posterior model probabilities for 0.333 < Bayes factor < 1 was 0.8.

CONCLUSIONS

In the current meta-analytic cohort, an integrated and multifaceted Bayesian approach gave support to including NRS in a pooled-estimate model. Conversely, caution should attend the reporting of naïve frequentist pooled, RCT and NRS, meta-analytic treatment effects.

A mass cytometry approach to track the evolution of T cell responses during infection and immunotherapy by paired T cell receptor repertoire and T cell differentiation state analysis

T cell receptor (TCR) recognition followed by clonal expansion is a fundamental feature of adaptive immune responses. Here, we developed a mass cytometric (CyTOF) approach combining antibodies specific for different TCR Vα- and Vβ-chains with antibodies against T cell activation and differentiation proteins to identify antigen-specific expansions of T cell subsets and assess aspects of cellular function. This strategy allowed for the identification of expansions of specific Vβ and Vα chain expressing CD8+ and CD4+ T cells with varying differentiation states in response to Listeria monocytogenes, tumors, and respiratory influenza infection. Expanded Vβ chain expressing T cells could be directly linked to the recognition of specific antigens from Listeria, tumor cells, or influenza. In the setting of influenza infection, we showed that the common therapeutic approaches of intramuscular vaccination or convalescent serum transfer altered the clonal diversity and differentiation state of responding T cells. Thus, we present a new method to monitor broad changes in TCR specificity paired with T cell differentiation during adaptive immune responses.

Therapeutic role of immunomodulators during the COVID-19 pandemic- a narrative review

The emergency state caused by COVID-19 saw the use of immunomodulators despite the absence of robust research. To date, the results of relatively few randomized controlled trials have been published, and methodological approaches are riddled with bias and heterogeneity. Anti-SARS-CoV-2 antibodies, convalescent plasma and the JAK inhibitor baricitinib have gained Emergency Use Authorizations and tentative recommendations for their use in clinical practice alone or in combination with other therapies. Anti-SARS-CoV-2 antibodies are predominating the management of non-hospitalized patients, while the inpatient setting is seeing the use of convalescent plasma, baricitinib, tofacitinib, tocilizumab, sarilumab, and corticosteroids, as applicable. Available clinical data also suggest the potential clinical benefit of the early administration of blood-derived products (e.g. convalescent plasma, non-SARS-CoV-2-specific immunoglobins) and the blockade of factors implicated in the hyperinflammatory state of severe COVID-19 (Interleukin 1 and 6; Janus Kinase). Immune therapies seem to have a protective effect and using immunomodulators alone or in combination with viral replication inhibitors and other treatment modalities might prevent progression into severe COVID-19 disease, cytokine storm and death. Future trials should address existing gaps and reshape the landscape of COVID-19 management.

Systematic review and meta-analysis of randomised controlled trials testing the safety and efficacy of convalescent plasma in the treatment of coronavirus disease 2019 (COVID-19): Evidence-base for practise and implications for research

BACKGROUND

Despite scientific advances, there is no effective medical therapy for coronavirus disease 2019 (COVID-19). This systematic review and meta-analysis aimed to evaluate the safety and efficacy of convalescent plasma therapy in COVID-19.

METHODS

This review was carried out in accordance with Cochrane methodology including risk of bias assessment and grading of the quality of evidence. Only prospective clinical trials randomly assigning COVID-19 patients to convalescent plasma plus standard of care therapy (test arm) versus placebo/standard of care (control arm) were included. Two reviewers independently read each preprint/publication and extracted relevant data from individual studies. Data were pooled using the random-effects model and expressed as risk ratio (RR) with 95% confidence interval (CI).

RESULTS

A total of 13 206 patients from 12 randomised controlled trials were included. There was no significant difference in clinical improvement rate (RR = 1.00, 95% CI: 0.98-1.02, p = 0.96) or time to clinical improvement (median difference of 1.08 days with 95% CI ranging from -0.15 to +2.30 days) between convalescent plasma versus placebo/standard of care therapy. The use of convalescent plasma was not associated with significantly reduced risk of death (RR = 0.81, 95% CI: 0.65-1.02, p = 0.08). Reassuringly, overall incidence of infusion-related serious adverse events was low (3.25%) and not significantly different (RR = 1.14, 95% CI: 0.93-1.40, p = 0.22) for convalescent plasma transfusion compared to placebo/standard of care therapy.

CONCLUSIONS

There is low to moderate certainty evidence that the addition of convalescent plasma to current standard of care therapy is generally safe but, does not result in any significant clinical benefit or reduction of mortality in COVID-19.

Convalescent Plasma-A Light at the End of the Tunnel: A Systematic Review and Meta-analysis of Randomized Controlled Trials

In the absence of a definitive therapy during this ongoing unprecedented crisis, coronavirus disease-2019 (COVID-19) pandemic, convalescent plasma transfusion (CPT) has shown some promising results. This review summarizes the existing evidence of the efficacy of CPT in COVID-19 patients based upon scientific publications to date. We have included only the randomized controlled trials (RCTs) through an extensive screening of electronic databases up to July 31, 2021. In 19 RCTs, with a total of 16,476 COVID-19 patients we found low-quality evidence of significant reduction in mortality (odds ratio (OR) = 0.80; 95% confidence interval (CI): 0.66-0.96, I2 = 40%), better clinical outcome when applied <7 days (OR = 2.13, 95% CI 1.28-3.53, I2 = 0%), and improved viral clearance (OR = 2.6, 95% CI: 1.3-5.45, I2 = 74%). Meta-regression analysis found that as a covariate, intubation on admission (p = 0.007) had a significant impact. However, there was any significant reduction neither in duration for clinical improvement (MD = -0.79, 95% CI: -2.76-1.18, I2 = 98%), nor in total period of hospital stay (MD = 0.02, 95% CI: -0.75-0.78, I2 = 81%). Early application of CPT is still relevant in reducing morbidity and mortality in critically ill patients and is too early to write it off as a potential therapeutic modality for COVID-19 patients.

HOW TO CITE THIS ARTICLE

Sarkar S, Khanna P, Singh AK. Convalescent -Plasma-A Light at the End of the Tunnel: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Indian J Crit Care Med 2021;25(11):1292-1300.

Safety and Efficacy of Convalescent Plasma in COVID-19: An Overview of Systematic Reviews

Convalescent plasma (CP) from patients recovered from COVID-19 is one of the most studied anti-viral therapies against SARS-COV-2 infection. The aim of this study is to summarize the evidence from the available systematic reviews on the efficacy and safety of CP in COVID-19 through an overview of the published systematic reviews (SRs). A systematic literature search was conducted up to August 2021 in Embase, PubMed, Web of Science, Cochrane and Medrxiv databases to identify systematic reviews focusing on CP use in COVID-19. Two review authors independently evaluated reviews for inclusion, extracted data and assessed quality of evidence using AMSTAR (A Measurement Tool to Assess Reviews) and GRADE tools. The following outcomes were analyzed: mortality, viral clearance, clinical improvement, length of hospital stay, adverse reactions. In addition, where possible, subgroup analyses were performed according to study design (e.g., RCTs vs. non-RCTs), CP neutralizing antibody titer and timing of administration, and disease severity. The methodological quality of included studies was assessed using the checklist for systematic reviews AMSTAR-2 and the GRADE assessment. Overall, 29 SRs met the inclusion criteria based on 53 unique primary studies (17 RCT and 36 non-RCT). Limitations to the methodological quality of reviews most commonly related to absence of a protocol (11/29) and funding sources of primary studies (27/29). Of the 89 analyses on which GRADE judgements were made, effect estimates were judged to be of high/moderate certainty in four analyses, moderate in 38, low in 38, very low in nine. Despite the variability in the certainty of the evidence, mostly related to the risk of bias and inconsistency, the results of this umbrella review highlight a mortality reduction in CP over standard therapy when administered early and at high titer, without increased adverse reactions.

Current systematic reviews and meta-analyses of COVID-19

BACKGROUND

Coronavirus disease 2019 (COVID-19) has left a significant impact on the world's health, economic and political systems; as of November 20, 2020, more than 57 million people have been infected worldwide, with over 1.3 million deaths. While the global spotlight is currently focused on combating this pandemic through means ranging from finding a treatment among existing therapeutic agents to inventing a vaccine that can aid in halting the further loss of life.

AIM

To collect all systematic reviews and meta-analyses published related to COVID-19 to better identify available evidence, highlight gaps in knowledge, and elucidate further meta-analyses and umbrella reviews that are yet to be performed.

METHODS

We explored studies based on systematic reviews and meta-analyses with the key-terms, including severe acute respiratory syndrome (SARS), SARS virus, coronavirus disease, COVID-19, and SARS coronavirus-2. The included studies were extracted from Embase, Medline, and Cochrane databases. The publication timeframe of included studies ranged between January 01, 2020, to October 30, 2020. Studies that were published in languages other than English were not considered for this systematic review. The finalized full-text articles are freely accessible in the public domain.

RESULTS

Searching Embase, Medline, and Cochrane databases resulted in 1906, 669, and 19 results, respectively, that comprised 2594 studies. 515 duplicates were subsequently removed, leaving 2079 studies. The inclusion criteria were systematic reviews or meta-analyses. 860 results were excluded for being a review article, scope review, rapid review, panel review, or guideline that produced a total of 1219 studies. After screening articles were categorized, the included articles were put into main groups of clinical presentation, epidemiology, screening and diagnosis, severity assessment, special populations, and treatment. Subsequently, there was a second subclassification into the following groups: gastrointestinal, cardiovascular, neurological, stroke, thrombosis, anosmia and dysgeusia, ocular manifestations, nephrology, cutaneous manifestations, D-dimer, lymphocyte, anticoagulation, antivirals, convalescent plasma, immunosuppressants, corticosteroids, hydroxychloroquine, renin-angiotensin-aldosterone system, technology, diabetes mellitus, obesity, pregnancy, children, mental health_, smoking, cancer, and transplant.

CONCLUSION

Among the included articles, it is clear that further research is needed regarding treatment options and vaccines. With more studies, data will be less heterogeneous, and statistical analysis can be better applied to provide more robust clinical evidence. This study was not designed to give recommendations regarding the management of COVID-19.

Efficacy and Safety of Convalescent Plasma for COVID-19: A Systematic Review and Meta-analysis

Convalescent plasma is currently being used in the treatment of COVID-19. Recommendations regarding use convalescent plasma in COVID-19 requires systematic summaries of available evidence. We searched the databases Medline, Embase, Cochrane CENTRAL, Epistomonikos, Medrxiv and Biorxiv. Title/abstract screening, full text screening and data abstraction were carried out in duplicate by two reviewers. Pooled effect sizes and 95% confidence intervals were calculated using random effects meta-analysis. GRADE tool was used to rate the certainty of evidence. Twenty two studies were found eligible for inclusion: nine randomized controlled trials and thirteen cohort studies. Low certainty evidence from eight RCTs showed inconclusive effects of convalescent plasma on mortality at 28 days (OR 0.85, 95% CI 0.61 to 1.18). Low certainty evidence from thirteen cohort studies showed a reduction in mortality at 28 days (OR 0.66, 95% CI 0.53 to 0.82). The pooled OR for clinical improvement was 1.07 (95% CI 0.86 to 1.34) representing low certainty evidence. Evidence from three RCTs showed inconclusive effect of CP on the need for mechanical ventilation (OR 1.20, 95% CI 0.72 to 1.98). Four cohort studies reporting unadjusted estimates suggested a reduction in the need for mechanical ventilation with convalescent plasma (OR 0.80 95% CI 0.71 to 0.91, low certainty). Pooled estimates from 2 RCTs showed inconclusive effects of convalescent plasma on the proportion of patients with nondetectable levels of virus in nasopharyngeal specimens on day 3 (OR 3.62, 95% CI 0.43, 30.49, very low-quality evidence). The present review reports uncertain estimates on the efficacy of convalescent plasma in the treatment of COVID-19. There is low certainty evidence of a possible reduction in mortality and mechanical ventilation, a faster viral clearance and the absence of any serious adverse events. However, its efficacy for these outcomes requires evidence from good quality and adequately powered randomized controlled trials.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12288-021-01417-w.

Clinical effectiveness of convalescent plasma in hospitalized patients with COVID-19: a systematic review and meta-analysis

AIMS

Given the variability of previously reported results, this systematic review aims to determine the clinical effectiveness of convalescent plasma employed in the treatment of hospitalized patients diagnosed with COVID-19.

METHODS

We conducted a systematic review of controlled clinical trials assessing treatment with convalescent plasma for hospitalized patients diagnosed with SARS-CoV-2 infection. The outcomes were mortality, clinical improvement, and ventilation requirement.

RESULTS

A total of 51 studies were retrieved from the databases. Five articles were finally included in the data extraction and qualitative and quantitative synthesis of results. The overall risk of bias in the reviewed articles was established at low-risk only in two trials. The meta-analysis suggests that there is no benefit of convalescent plasma compared with standard care or placebo in reducing the overall mortality and the ventilation requirement. However, there could be a benefit for the clinical improvement in patients treated with plasma.

CONCLUSION

Current results led to assume that the convalescent plasma transfusion cannot reduce the mortality or ventilation requirement in hospitalized patients diagnosed with SARS-CoV-2 infection. More controlled clinical trials conducted with methodologies that ensure a low risk of bias are still needed.The reviews of this paper are available via the supplemental material section.