Predicting postdischarge hospital-associated venous thromboembolism among medical patients using a validated mortality risk score derived from common biomarkers

Predicting post-discharge venous thromboembolism and bleeding among medical patients: External validation of a novel risk score utilizing ubiquitous biomarkers

BACKGROUND

Post-hospitalization thromboprophylaxis can reduce venous thromboembolism (VTE) risk for non-surgical patients but may carry bleeding risks. We aimed to externally validate the Intermountain Risk Scores for hospital-associated venous thromboembolism (HA-VTE IMRS) and major bleeding (HA-MB IMRS) for VTE and bleeding outcomes.

METHODS

Retrospective cohort study of adult patients discharged alive from medical services between 2015 and 2019. HA-VTE IMRS and HA-MB IMRS were calculated at the time of hospital discharge and dichotomized as high- or low-risk as described in the derivation manuscript. 90-day post-discharge VTE outcomes were assessed from diagnostic radiology reports, and bleeding outcomes were assessed using ICD-10 codes and blood bank transfusion records.

RESULTS

Among 113,578 patients in the study, 66,340 patients (58.4 %) had a low-risk HA-VTE IMRS <7, versus 47,238 (41.6 %) high-risk ≥7. For bleed prediction, 71,576 patients (63 %) had a low-risk HA-MB IMRS <8, versus 42,002 (37 %) high-risk ≥8. VTE incidence was 1.1 % and 0.6 % while major bleeding incidence was 1.3 % and 0.1 % in high-risk versus low-risk cohorts, respectively. AUCs for VTE and bleed outcome discrimination were 0.59 and 0.78, respectively. Patients with a combined high-risk VTE score and low-risk bleeding score comprised 14.5 % of the population.

CONCLUSION

In this external validation study, the HA-VTE IMRS had poor discrimination for VTE but the HA-MB IMRS had good discriminatory ability for major bleeding events. A sizable minority of patients were categorized as high VTE risk with low bleed risk, a population which may have an optimal risk-benefit profile for post-hospital thromboprophylaxis.

Post-discharge thrombosis and bleeding in medical patients: A novel risk score derived from ubiquitous biomarkers

BACKGROUND

Some hospitalized medical patients experience venous thromboembolism (VTE) following discharge. Prophylaxis extended beyond hospital discharge (extended duration thromboprophylaxis [EDT]) may reduce this risk. However, EDT is costly and can cause bleeding, so selecting appropriate patients is essential. We formerly reported the performance of a mortality risk prediction score (Intermountain Risk Score [IMRS]) that was minimally predictive of 90-day hospital-associated venous thromboembolism (HA-VTE) and major bleeding (HA-MB). We used the components of the IMRS to calculate de novo risk scores to predict 90-day HA-VTE (HA-VTE IMRS) and major bleeding (HA-MB IMRS).

METHODS

From 45 669 medical patients we randomly assigned 30 445 to derive the HA-VTE IMRS and the HA-MB IMRS. Backward stepwise regression and bootstrapping identified predictor covariates from the blood count and basic chemistry. These candidate variables were split into quintiles, and the referent quintile was that with the lowest event rate for HA-VTE and HA-MB; respectively. A clinically relevant rate of HA-VTE and HA-MB was used to inform outcome rates. Performance was assessed in the derivation set of 15 224 patients.

RESULTS

The HA-VTE IMRS and HA-MB IMRS area under the receiver operating curve (AUC) in the derivation set were 0.646, and 0.691, respectively. In the validation set, the HA-VTE IMRS and HA-MB IMRS AUCs were 0.60 and 0.643.

CONCLUSIONS

Risk scores derived from components of routine labs ubiquitous in clinical care identify patients that are at risk for 90-day postdischarge HA-VTE and major bleeding. This may identify a subset of patients with high HA-VTE risk and low HA-MB risk who may benefit from EDT.