Abstract Number: PB1307
Meeting: ISTH 2020 Congress
Background: Hospital-acquired venous thromboembolism (HA-VTE) in children comprises multiple risk factors that should not be evaluated separately due to collinearity and multiple cause/effect relationships. This limitation may be overcome by the use of Directed Acyclic Graph (DAG) analysis.
Aims: To evaluate thrombotic risk factors in a pediatric hospital setting using an alternative statistical methodology to differentiate exposures and confounders.
Methods: Retrospective, case-control study with 24 cases of objectively confirmed HA-VTE and 76 controls matched by age, sex, unit of admission, and period of hospitalization. Descriptive statistics were used to define distributions of continuous variables, frequencies, and proportions of categorical variables, with a comparison between cases and controls. Due to a large number of potential risk factors of HA-VTE, a DAG model was created to identify confounding, reduce bias, and increase precision on the analysis. The final model consisted of a DAG-based logistic regression. The study was approved by the institutional review board and consent was waived.
Results: In the univariable model, the following variables were selected as potential risk factors for HA-VTE: length of stay (LOS, days), immobility, ICU admission in the last 30 days, LOS in ICU, infection, central venous catheter (CVC), number of CVCs placed, L-asparaginase, heart failure, liver failure and nephrotic syndrome (NS). Using the DAG methodology, confounders and exposures were differentiated (Fig. 1).The final model (Table 1) revealed LOS (OR=1.05, 95%CI=1.02-1.08, p< 0.001), liver failure (OR=8.90, 95%CI=1.02-77.73, p=0.05), L-asparaginase (OR=23.49, 95%CI=3.35-164.59, p=0.001), and NS (OR=36.10, 95%CI=3.22-404.85, p=0.004) as independent risk factors.
Conclusions: The DAG-based approach was useful to clarify the influence of confounders and multiple causalities of HA-VTE. Interestingly, CVC placement, a known thrombotic risk factor, was considered a confounder, while liver failure, LOS, L-asparaginase use and nephrotic syndrome were confirmed as risk factors to HA-VTE. Large confidence intervals are related to the sample size, however the results were significant.
[Figure 1. Directed acyclic graph (DAG) model of hospital-acquired venous thromboembolism (HA-VTE) in children]
| Variable | Full Model OR (95%CI) | Full Model p-value | Final Model OR (95%CI) | Final Model p-value |
| Length of stay | 1.066 (1.016-1.119) | 0.010 | 1.054 (1.024-1.084) | <0.001 |
| Liver failure | 15.736 (0.773-320.276) | 0.073 | 8.891 (1.017-77.725) | 0.048 |
| L-asparaginase | 621.588 (4.352-88,770.419) | 0.011 | 23.493 (3.353-164.588) | 0.001 |
| Nephrotic syndrome | 227.560 (4.416-11,726.072) | 0.007 | 36.096 (3.218-404.846) | 0.004 |
| ICU admission | 14.290 (0.705-289.568) | 0.083 | ||
| Catheter | 16.177 (0.849-308.342) | 0.064 | ||
| Obesity | 5.450 (0.388-76.452) | 0.208 | ||
| Hematologic malignancies | 0.022 (0.000-1.135) | 0.058 | ||
| Immobilization | 0.672 (0.044-10.272) | 0.775 |
[Table 1. Multivariable regression models]
To cite this abstract in AMA style:
Campos LR, Petroli M, R Sztajnbok F, Costa ES, R Brandao L, Land MGP. Risk Factors for the Development of Hospital-acquired Pediatric Thromboembolism – Dealing with Potentially Causal and Confounding Risk Factors Using Direct Acyclic Graph (DAG) Analysis [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/risk-factors-for-the-development-of-hospital-acquired-pediatric-thromboembolism-dealing-with-potentially-causal-and-confounding-risk-factors-using-direct-acyclic-graph-dag-analysis/. Accessed September 29, 2023.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/risk-factors-for-the-development-of-hospital-acquired-pediatric-thromboembolism-dealing-with-potentially-causal-and-confounding-risk-factors-using-direct-acyclic-graph-dag-analysis/