Predictors and mortality risk of venous thromboembolism in patients with COVID-19: systematic review and meta-analysis of observational studies
Bibliographic record
Abstract
Introduction: Novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection resulting in COVID-19 disease is associated with widespread inflammation and a prothrombotic state, resulting in frequent venous thromboembolic (VTE) events. It is currently unknown whether anticoagulation is protective for VTE events. Therefore, we conducted a systematic review to identify predictors of VTE in COVID-19. Methods: We searched PubMed, EMBASE, Google Scholar, and Ovid databases for relevant observational studies of VTE in COVID-19 disease. The effect size for predictors of VTE was calculated using a random-effects model and presented as forest plots. Heterogeneity among studies was expressed as Q statistics and I2. Bias was assessed using the Newcastle Ottawa Scale for all identified observational studies. Publication bias was assessed with funnel plot analysis. Results: We identified 28 studies involving 6053 patients with suspected or confirmed COVID-19. The overall pooled prevalence of VTE events was 20.7%. Male sex was associated with a higher risk of VTE events, whereas prior history of VTE, smoking, and cancer were not. VTE events were significantly higher in severely ill patients, mechanically ventilated patients, those requiring intensive care admission, and those with a low PaO2/FiO2 ratio (P/F ratio). Chronic comorbidities, including cardiovascular disease, heart failure, renal disease, and pulmonary disease, did not increase the risk of VTE events. Patients with VTE had higher leukocyte counts and higher levels of D-dimer, C-reactive protein, and procalcitonin. The occurrence of VTE was associated with increased length of stay but did not impact mortality. Therapeutic and prophylactic doses of anticoagulation were not protective against VTE. Conclusion: VTE in COVID-19 is associated with male gender and severe disease but not with traditional risk factors for VTE. The occurrence of VTE does not appear to be mitigated by either prophylactic or therapeutic anticoagulation. The occurrence of VTE in this population is associated with an increased length of stay but does not appear to impact mortality.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.012 | 0.033 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.017 | 0.032 |
| Bibliometrics | 0.007 | 0.008 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".