A Cancer-Modified Pulmonary Embolism Severity Index Score Expands Outpatient Eligibility

Many society guidelines recommend the validated Pulmonary Embolism (PE) Severity Index (PESI) to identify low-risk patients who may be eligible for outpatient care. In the original PESI, active and inactive cancer are treated as equivalents. Adverse outcomes in PE patients, however, correlate more with active cancer (e.g., metastatic) than remote inactive cancer (e.g., only local disease, excised 10 years prior, without recurrence). A few studies and clinical pathways have modified PESI (mod-PESI) by assigning cancer points only for active disease. The degree to which mod-PESI expands outpatient eligibility has not been explored.

This is a secondary analysis of a retrospective cohort study conducted across 21 U.S. community hospitals from 2013-2019. It included ambulatory adults diagnosed with PE in primary care to evaluate outpatient management (discharge home) both from the clinic and, for those referred, from the emergency department (ED). We included only those with vital signs (VSs) in the clinic or ED, using the most abnormal values for scoring. Active cancer was metastatic disease or recent (<12 months) diagnosis, anticancer treatment or palliative care. We compared proportions of low-risk patients (mod-PESI vs PESI) in clinic and the ED using McNemar exact test and calculated marginal Wald-type confidence intervals (CIs) on the differences in proportions. We reported 30-day major bleed, recurrent venous thromboembolism (VTE), and mortality among those reclassified.

Of 652 patients in the parent study, 16 were excluded for lacking VSs. Of the remaining 636, median age was 65 years (interquartile range 51-74), 52% were male. Overall, 132 (20.8%) had cancer: 49 (7.7%) active and 83 (13.1%) only inactive cancer; 175 had only clinic VSs, 50 had only ED VSs (after a virtual clinic visit), and 411 had both. In the clinic (n=586), mod-PESI classified more patients as low risk than PESI: 72.7% vs 64.5%, difference 8.2% (95% CI 5.9%–10.5%) (p<0.001). Similarly in the ED cohort (n=461): mod-PESI 70.9% vs PESI 63.3%, difference 7.6% (95% CI 5.1%–10.1%) (p<0.001). There were no 30-day outcomes among those reclassified.

Mod-PESI, using an active-only cancer definition, classified a statistically significantly greater proportion of ambulatory PE patients as low-risk. Effect of mod-PESI use on disposition among unselected ED patients in different settings merits study.