Prognostic value of venous thromboembolism risk scores in patients with severe COVID-19
The International Medical Prevention Registry on Venous Thromboembolism (IMPROVE) and Caprini risk scores were independent predictors of mortality and thrombotic events in patients with severe coronavirus disease (COVID-19).
- Among patients hospitalized for severe COVID-19, IMPROVE and Caprini risk assessment models were both strong and independent predictors of mortality.
- The two scores also strongly and independently predicted thrombotic events among patients classified at “high risk for venous thromboembolism (VTE)” by either risk assessment model (RAM).
Why This Matters
- Particular endothelial involvement and high VTE incidence in patients with COVID-19 are highly associated with worse outcomes; however, the optimal way to classify these patients is unclear.
- This study assessed if VTE RAMs, like IMPROVE and Caprini scores, can provide prognostic information and predict mortality in patients with severe COVID-19.
- The present retrospective, observational study enrolled consecutive patients hospitalized for severe COVID-19 from the NorthShore University Health System (March 12, 2020–July 30, 2020).
- Inclusion criteria: Patients (≥18 years) with severe acute respiratory syndrome-coronavirus-2 infection confirmed by polymerase chain reaction
- According to the IMPROVE risk score, patients were classified into low (score 0–1), moderate (score 2–3), and high risk for VTE (score ≥4).
- According to the Caprini score, patients were classified as follows: Very low (score: 0–2), moderate (score: 3–4), high (score: 5–6), very high (score: 7–8), and the highest risk (score: >8)
- Outcomes: (1) VTE (deep vein thrombosis or pulmonary embolism) and (2) clinical and mortality outcomes
- In total, 184 patients with severe COVID-19 were included (men, 63.6%; age, 63 [interquartile range: 24–101] years).
IMPROVE score and mortality
- Moderate and high risk for VTE by IMPROVE score were significantly associated with mortality (hazard ratio [HR] = 2.02; 95% confidence interval [CI]: 1.27–3.21; P = 0.003 vs HR = 2.49; 95% CI: 1.62–3.83; P <0.001), with 87% sensitivity and 63% specificity (area under the curve [AUC] = 0.752, P <0.001).
- In multivariate Cox’s regression analysis, the association stayed significant for the following:
- High risk for VTE (HR = 6.22; 95% CI: 3.04–12.71; P <0.001)
- Moderate risk for VTE (HR = 5.68; 95% CI: 2.93–11.03; P <0.001)
- Diabetes presence (HR = 1.70; 95% CI: 1.10–2.63; P = 0.016)
- Hypertension presence (HR = 1.63; 95% CI: 1.02–2.59; P <0.040)
- In-hospital mortality in patients at low, moderate, and high risk for VTE was 15.1%, 66.7%, and 68.1%, respectively.
Caprini score and mortality
- High risk for VTE by Caprini score had significant association with mortality (HR = 18.6; 95% CI: 5.87–59.06; P <0.001), with 96% sensitivity and 55% specificity (AUC = 0.843, P <0.001).
- This association remained significant in multivariate Cox’s regression analysis (HR = 17.6; 95% CI: 5.56–55.96; P <0.001), followed by the presence of diabetes (HR = 1.60; 95% CI: 1.05–2.46; P = 0.029).
- Patients at very low, moderate, high, very high, and the highest risk had 0%, 6.8%, 44.4%, 60.8%, and 80% mortality rate.
Prediction of thrombotic events
- In univariate and multivariate analyses, patients at high risk for VTE by IMPROVE and Caprini scores were statistically associated with thrombotic event occurrence (HR = 6.50; 95% CI: 2.72–15.53; P <0.001 and HR = 11.507; 95% CI: 2.697–49.104; P = 0.001, respectively).
- Those with moderate risk for VTE by IMPROVE score were not statistically related with thrombotic event incidence (HR = 2.82; 95% CI: 0.62–12.75; P = 0.177).
- The cumulative incidence of VTE for patients with low, moderate, and high risk for VTE was 5.5%, 7.7%, and 27.8%, respectively.
- Based on Caprini scores, patients classified at very low, moderate, high, very high, and the highest risk had a VTE incidence of 0%, 4.5%, 7.4%, 17.6%, and 28.0%, respectively.
- The study was observational in nature, had relatively small sample size, and enrolled patients from a single center.
- Owing to missed routine screenings for VTE or autopsies during the pandemic, it could not be verified whether the deaths were related to VTE.
- The true number of thrombotic events was probably underestimated.
- Severity of disease from COVID-19 introduced selection bias, limiting generalizability of results to all patients with COVID-19.
- Owing to retrospective design, a formal power calculation was not performed.
- Paz Rios LH, Minga I, Kwak E, Najib A, Aller A, Lees E, et al. Prognostic value of venous thromboembolism risk assessment models in patients with severe COVID-19. TH Open. 2021;5(2):e211–e219. doi: 10.1055/s-0041-1730293. PMID: 34179684.