Appropriateness of Pharmacologic Thromboprophylaxis Prescribing Based on Padua Score Among Inpatient Veterans
Background: Hospitalized patients are at increased risk of developing venous thromboembolism (VTE). The Padua Prediction Score (PPS) was developed to help quantify the risk of VTE for hospitalized patients and guide prescribing of pharmacologic thromboprophylaxis. This study aims to assess whether PPS embedded within an admission order set was utilized appropriately to prescribe or withhold pharmacologic thromboprophylaxis.
Methods: This single center, retrospective observational cohort study evaluated adult patients aged ≥ 18 years between June 2017 and June 2020. A random sample of 250 patient charts meeting inclusion criteria were reviewed to calculate PPSs, and clinician notes were reviewed for documentation as to whether thromboprophylaxis was given or withheld appropriately based on the PPS. A second cohort of patients admitted within the study period meeting inclusion criteria and readmitted for VTE within 45 days of discharge were evaluated to determine appropriateness of inpatient VTE thromboprophylaxis during index hospitalization based on the PPS.
Results: Of the 250 patients examined, 118 (47.2%) had a PPS < 4 on admission. Of the 118 patients, 58 (49.2%) were inappropriately prescribed pharmacologic thromboprophylaxis administered within 24 hours of admission. The clinical rationale for giving thromboprophylaxis when not indicated was provided for only 2 (3.4%) of the 58 patients. Of the 132 patients with a PPS ≥ 4, 11 (8.3%) had thromboprophylaxis appropriately withheld and for 33 (25.0%) it was inappropriately withheld. A total of 88 (66.7%) patients received thromboprophylaxis as indicated by a PPS ≥ 4.
Conclusions: Despite the inclusion of the PPS calculator in the facility’s admission order set, this study showed pharmacologic thromboprophylaxis was frequently inappropriately given or withheld. This suggests written protocols and order sets may not be solely sufficient to ensure appropriate VTE prophylaxis in actual practice. Incorporation of additional tools, such as dashboards and scorecards, should be explored.
A secondary endpoint characterized patients at highest risk for developing a VTE after hospitalization for an acute illness. Seventy patients were readmitted within 45 days of discharge from the index hospitalization with ICD descriptions for embolism or thrombosis. Only 15 of those patients were readmitted with a newly diagnosed VTE not previously identified; 14 (93.3%) had a PPS ≥ 4 upon index admission and 10 (66.7%) appropriately received pharmacologic prophylaxis within 24 hours of admission. Of the 15 patients, 3 (20.0%) did not receive pharmacologic thromboprophylaxis within 24 hours of admission and 1 (6.7%) received thromboprophylaxis despite having a PPS < 4.
Looking at IMPROVEDD scores for the 15 patients at the index hospitalization discharge, 1 (6.7%) patient had an IMPROVEDD score < 2, 11 (73.3%) patients had IMPROVEDD scores ≥ 2, and 3 (20.0%) patients had IMPROVEDD scores ≥ 4. Two of the patients with IMPROVEDD scores ≥ 4 had a history of VTE and were aged > 60 years. Of the 15 patients reviewed, 7 had a diagnosis of cancer, and 3 were actively undergoing chemotherapy.
Discussion
PPS is the RAM embedded in our system’s order set, which identifies hospitalized medical patients at risk for VTE.6 In the original study that validated PPS, the results suggested that implementation of preventive measures during hospitalization in patients labeled as having high thrombotic risk confers longstanding protection against thromboembolic complications in comparison with untreated patients.6 However, PPS must be used consistently and appropriately to realize this benefit. Our results showed that pharmacologic thromboprophylaxis is frequently inappropriately given or withheld despite the incorporation of a RAM in an admission order set, suggesting there is a significant gap between written policy and actual practice. More than one-third of patients had thromboprophylaxis given or withheld inappropriately according to the PPS calculated manually on review. With this, there is concern for over- and underprescribing of thromboprophylaxis, which increases the risk of adverse events. Overprescribing can lead to unnecessary bleeding complications, whereas underprescribing can lead to preventable VTE.
One issue identified during this study was the need for a user-friendly interface. The PPS calculator currently embedded in our admission order set is a hyperlink to an online calculator. This is time consuming and cumbersome for clinicians tending to a high volume of patients, which may cause them to overlook the calculator and estimate risk based on clinician judgement. Noted areas for improvement regarding thromboprophylaxis during inpatient admissions include the failure to implement or adhere to risk stratification protocols, lack of appropriate assessment for thromboprophylaxis, and the overutilization of pharmacologic thromboprophylaxis in low-risk patients.11
Certain patients develop a VTE postdischarge despite efforts at prevention during their index hospitalization, which led us to explore our secondary endpoint looking at readmissions. Regarding thromboprophylaxis postdischarge, the duration of therapy is an area of current debate.5 Extended-duration thromboprophylaxis is defined as anticoagulation prescribed beyond hospitalization for up to 42 days total.1,12 To date, there have been 5 clinical trials to evaluate the utility of extended-duration thromboprophylaxis in hospitalized medically ill patients. While routine use is not recommended by the 2018 American Society of Hematology guidelines for management of VTE, more recent data suggest certain medically ill patients may derive benefit from extended-duration thromboprophylaxis.4 The IMPROVEDD score aimed to address this need, which is why it was calculated on index discharge for our patients readmitted within 45 days. Research is still needed to identify such patients and RAMs for capturing these subpopulations.1,11
Our secondary endpoint sought to characterize patients at highest risk for developing a VTE postdischarge. Of the 15 patients reviewed, 7 had a diagnosis of cancer and 3 were actively undergoing chemotherapy. With that, the Khorana Risk Score may have been a more appropriate RAM for some given the Khorana score is validated in ambulatory patients undergoing chemotherapy. D-dimer was only collected for 1 of the 15 patients, therefore, VTE risk could have been underestimated with the IMPROVEDD scores calculated. More than 75% of patients readmitted for VTE appropriately received thromboprophylaxis on index admission yet still went on to develop a VTE. It is essential to increase clinician awareness about hospital-acquired and postdischarge VTE. In line with guidance from the North American Thrombosis Forum, extended-duration thromboprophylaxis should be thoughtfully considered in high-risk patients.5 Pathways, including follow-up, are needed to implement postdischarge thromboprophylaxis when appropriate
