SynthesisFrontiers in immunology
Serum Complement C3 and C4 and COVID-19 Severity and Mortality: A Systematic Review and Meta-Analysis With Meta-Regression.
Synthesis in Frontiers in immunology. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 48 papers, 1 of them a synthesis that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
48 citing papers in PubMed, 1 synthesis or guideline pooled it, 85 citations in OpenAlex.
- Systemic inflammation index, disease severity, and mortality in patients with COVID-19: a systematic review and meta-analysis.Frontiers in immunology · 2023Pooled it
- Efficacy and safety of the investigational complement C5 inhibitor zilucoplan in patients hospitalized with COVID-19: an open-label randomized controlled trial.Respiratory research · 2022Trial
- Increased anti-nucleocapsid secretory IgA and consumption of complement component 3 in post-COVID syndrome patients.Frontiers in immunology · 2026Article
- C3d Complement Activation and Antibody Immunity in Convalescent COVID-19: Insights From Adults and Children.Journal of immunology research · 2026Article
- Cross-platform clinical proteomics using the Charité open standard for plasma proteomics (OSPP).Nature communications · 2025Article
- Article
- Article
- Dual inflammation in schizophrenia infected with COVID-19: Impact on cognitive function.Brain, behavior, & immunity - health · 2025Article
- The schizophrenia risk gene C4 induces pathological synaptic loss by impairing AMPAR trafficking.Molecular psychiatry · 2025Article
- Current Scenario in Associating Clinical COVID-19 Biomarkers for Developing Surveillance Platforms.Current medicinal chemistry · 2025Review
- Role of interleukin 6 polymorphism and inflammatory markers in outcome of pediatric Covid- 19 patients.BMC pediatrics · 2024Article
- COVID-19 Coagulopathy.Life (Basel, Switzerland) · 2024Review
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- Article
- De-stabilizing innate immunity in COVID-19: effects of its own positive feedback and erratic viraemia on the alternative pathway of complement.Royal Society open science · 2024Article
- Epidemiological and clinical features of SARS-CoV-2 Omicron variant infection in Quanzhou, Fujian province: a retrospective study.Scientific reports · 2023Article
- Association of Serum Complement C3 Levels with Severity and Mortality in COVID 19.Indian journal of clinical biochemistry : IJCB · 2023Article
- Soluble TREM-1 plasma concentration predicts poor outcome in COVID-19 patients.Intensive care medicine experimental · 2023Article
- Complement and COVID-19: Three years on, what we know, what we don't know, and what we ought to know.Immunobiology · 2023Review
- SARS-CoV-2 Related Antibody-Dependent Enhancement Phenomena In Vitro and In Vivo.Microorganisms · 2023Review
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
2 authors at 2 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Activation of the complement system has been observed in coronavirus disease 19 (COVID-19). We conducted a systematic review and meta-analysis with meta-regression to investigate possible differences in the serum concentrations of two routinely measured complement components, C3 and C4, in COVID-19 patients with different severity and survival status. We searched PubMed, Web of Science and Scopus, between January 2020 and February 2021, for studies reporting serum complement C3 and C4, measures of COVID-19 severity, and survival. Eligibility criteria were a) reporting continuous data on serum C3 and C4 concentrations in COVID-19 patients, -b) investigating COVID-19 patients with different disease severity and/or survival status, c) adult patients, d) English language, e) ≥10 patients, and f) full-text available. Using a random-effects model, standardized mean differences (SMD) with 95% confidence intervals (CIs) were calculated to evaluate differences in serum C3 and C4 concentrations between COVID-19 patients with low vs. high severity or survivor vs. non-survivor status. Risk of bias was assessed using the Newcastle-Ottawa scale whereas publication bias was assessed with the Begg's and Egger's tests. Certainty of evidence was assessed using GRADE. Nineteen studies in 3,764 COVID-19 patients were included in the meta-analysis. Both C3 and C4 concentrations were significantly lower in patients with high disease severity or non-survivor status than patients with low severity or survivor status (C3 SMD=-0.40, 95% CI -0.60 to -0.21, p<0.001; C4 SMD=-0.29, 95% CI -0.49 to -0.09, p=0.005; moderate certainty of evidence). Extreme between-study heterogeneity was observed (C3, I
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