External Validation of a Clinical and Claims-Based Approach for Predicting 90-Day Post-Pulmonary Embolism Outcomes Among US Veterans

Background: Both the simplified Pulmonary Embolism Severity Index (sPESI) and the multivariable In-hospital Mortality for Pulmonary embolism using Claims daTa (IMPACT) rule classify patients' risk of early post-pulmonary embolism (PE) complications.

Objective: To externally validate sPESI and IMPACT for predicting 90-day all-cause mortality and readmission rates among PE patients treated within the Veterans Health Administration (VHA).

Methods: We used VHA data from 10/1/2010-9/30/2015 to identify adult patients with: (1) ≥1 inpatient diagnosis for acute PE (International Classification of Diseases-9^th Revision-Clinical Modification codes=415.1x), (2) continuous medical and pharmacy enrollment for ≥12-months prior to the index PE (baseline period), (3) a minimum of 90-days of post-event follow-up or until death (whichever came first), and (4) ≥1 claim for an anticoagulant during the index PE stay. Patients were excluded if they had a claim for PE or an anticoagulant during the baseline period. We classified patients as low-risk for early post-PE complications if their sPESI score=0 or their absolute in-hospital mortality risk estimated by IMPACT was <1.5% (the latter calculated using the formula: 1/(1 + exp(-x); where x = −5.833 + [0.026*age] + [0.402*myocardial infarction] + [0.368*chronic lung disease] + [0.464*stroke] + [0.638*prior major bleeding] + [0.298*atrial fibrillation] + [1.06 1*cognitive impairment] + [0.554*heart failure] + [0.364*renal failure] + [0.484*liver disease] + [0.523*coagulopathy] + [1.068*cancer]). Sensitivity, specificity, negative and positive predictive value (NPV and PPV) for all-cause mortality, all-cause readmission, and readmission for recurrent venous thromboembolism (VTE) or major bleeding at 90-days were reported with 95% confidence intervals (CIs) for sPESI and IMPACT tools.

Results: Of6,746 eligible PE patients, 851 (12.6%) died and 1,359 (20.1%) were readmitted for any reason within 90-days. Hospitalization for recurrent VTE and major bleeding occurred in 375 (5.6%) and 116 (1.7%), respectively.sPESI classified 1,918 (28.4%) as low-risk, while 1,024 (15.2%) were low-risk per IMPACT. Both tools displayed sensitivity >90% and NPVs >96% for all-cause 90-day mortality, but low specificity and PPVs (Table). IMPACT's sensitivity for all-cause readmission was numerically higher than sPESI, but both had comparable NPVs. Similar trends were observed for accuracy in predicting readmissions due to recurrent VTE or major bleeding.

Conclusion: In this external validation study utilizing VHA data, IMPACT classified patients for 90-day post-PE outcomes with similar accuracy as sPESI. While not recommended for prospective clinical decision-making, IMPACT appears useful for identification of PE patients at low-risk for early mortality or readmission in retrospective claims-based studies.

Table.

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Test characteristics for sPESI and IMPACT for 90-day post-pulmonary embolism outcomes CI= confidence interval; IMPACT=In-hospital Mortality for Pulmonary embolism using Claims data; NPV=negative predictive value; PPV=positive predictive value; sPESI=simplified Pulmonary Embolism Severity Index; VTE=venous thromboembolism

Table.

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Test characteristics for sPESI and IMPACT for 90-day post-pulmonary embolism outcomes CI= confidence interval; IMPACT=In-hospital Mortality for Pulmonary embolism using Claims data; NPV=negative predictive value; PPV=positive predictive value; sPESI=simplified Pulmonary Embolism Severity Index; VTE=venous thromboembolism

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