Development of a new risk score for hospital-associated venous thromboembolism in critically-ill children not undergoing cardiothoracic surgery

Background Although risk of hospital-associated venous thromboembolism (HA-VTE) differs between critically and non-critically ill children, studies to date have not led to distinct, pragmatic risk scores. Objective To determine risk factors for HA-VTE in critically ill children not undergoing cardiothoracic surgery, in order to derive a novel HA-VTE risk score for this population. Methods We conducted a retrospective analysis from January 2006 through April 2013 at All Children's Hospital Johns Hopkins Medicine. HA-VTE cases were identified using ICD-9 discharge diagnosis codes, with subsequent validation via radiologic record review. Cases were restricted to Pediatric Intensive Care Unit (PICU) admissions. Patients who underwent cardiothoracic surgery were excluded; cardiac catheterization per se was not exclusionary. For each case, three non-HA-VTE PICU controls were randomly selected. Data were abstracted on putative risk factors, and associations between risk factors and HA-VTE were estimated using odds ratios (ORs) and 95% confidence intervals (95%CIs). Results There were 57 HA-VTE cases and 171 controls. HA-VTE occurrence was 3 per 1000 PICU admissions (0.3%). Central venous catheter (CVC) (OR:26.64; 95%CI:7.46-95.13), length of stay (LOS) ≥ 4 days (OR:20.22; 95%CI:2.27-180.07), and significant infection (OR:3.41; 95%CI:1.13-10.29) were independent, statistically-significant risk factors for HA-VTE in a multivariate model. A risk score was derived in which HA-VTE risk exceeded 2% (threshold for anticoagulant thromboprophylaxis in hospitalized adults) with a score of 15, and was > 1% but < 2% (risk zone for mechanical thromboprophylaxis in hospitalized adults) with scores of 7-14. Conclusion The presence of a CVC, LOS ≥ 4 days and infection are significant risk factors for HA-VTE in critically ill children not undergoing cardiothoracic surgery, forming the basis for a new risk score that warrants prospective validation.