Frailty Impact on In-Hospital Outcomes Among Patients Hospitalized with Acute Pulmonary Embolism: A National Inpatient Sample Analysis

Background/Objectives: Acute pulmonary embolism (PE) can be life-threatening, and outcomes vary considerably between patients. Frailty reflects reduced physiologic reserve and may help describe vulnerability during an acute illness. We examined the association between the Hospital Frailty Risk Score (HFRS) and in-hospital outcomes among adults admitted with acute PE. Methods: We analyzed adult hospitalizations for acute PE recorded in the U.S. National Inpatient Sample between 2016 and 2021. HFRS was reconstructed from 109 three-character ICD-10 categories, with each category counted once per hospitalization and grouped as low (<5), intermediate (5–15), or high (>15). Survey-weighted logistic regression used NIS discharge weights, year-specific strata, and year-specific hospital clusters. Additional analyses were limited to patients aged ≥65 and ≥75 years, adjusted for available PE-severity markers and repeated with a modified HFRS that excluded potentially acute components. Results: The study included 220,455 unweighted hospitalizations, representing an estimated 1,102,274 U.S. hospitalizations. Low, intermediate, and high HFRS categories accounted for 67.1%, 31.5%, and 1.5%, respectively. In-hospital mortality was 1.2%, 7.1%, and 9.7% across these groups. Mechanical ventilation occurred in 0.9%, 7.9%, and 16.2%, acute ischemic stroke in 0.2%, 1.3%, and 6.4%, and major bleeding in 1.2%, 4.8%, and 9.3%, respectively. Compared with low HFRS, high HFRS was associated with higher odds of mortality (aOR 8.30, 95% CI 7.24–9.52), mechanical ventilation (aOR 27.74, 95% CI 24.59–31.31), circulatory support (aOR 19.18, 95% CI 11.83–31.11), acute ischemic stroke (aOR 37.61, 95% CI 30.45–46.46), and major bleeding (aOR 7.65, 95% CI 6.68–8.76). Associations persisted in age-restricted and severity-adjusted analyses but were substantially attenuated when potentially acute HFRS components were excluded. Conclusions: Higher HFRS categories were associated with worse in-hospital outcomes in acute PE. Associations were weaker after removing HFRS components that may reflect acute conditions, suggesting that same-admission coding may explain part of the association. Further prospective studies are needed before HFRS is used for treatment decisions or as an additional prognostic tool in acute PE.