Weekend admission and in‑hospital outcomes in cancer-related pulmonary embolism (CAP): A 2016–2022 national inpatient sample study

Abstract Introduction Cancer-related pulmonary embolism (CAP) is a common, lethal complication in patients with solid or hematologic malignancies. While overall PE mortality has declined, concern remains that patients admitted on weekends - when staffing and specialist coverage are reduced - experience poorer outcomes. Prior work on the weekend effect in venous thrombo-embolism is inconsistent and rarely oncology-focused; high tumor burden, multi-morbidity, and complex therapies may widen weekend care gaps. It is also unknown whether risk varies by cancer type or hospital profile. Using the 2016–2022 National Inpatient Sample, we evaluated the weekend–mortality association in CAP and explored modifiers at patient, tumor, and hospital levels. Methods We performed a retrospective, cross-sectional analysis of the 2016–2022 NIS, which approximates a 20 % stratified sample of U.S. hospital discharges and is weighted to generate national estimates. Adults (≥18 y) with a principal diagnosis of pulmonary embolism (ICD-10-CM codes I26.x) and at least one secondary malignancy code (C00–C96, D45, D46, D47) were classified as CAP admissions. Weekend admission was defined by the HCUP variable AWEEKEND (1 = Saturday/Sunday). The primary outcome was all-cause in-hospital mortality. Secondary outcomes included mechanical ventilation, inferior vena cava filter placement, administration of vasopressors, length of stay, and total charges, etc. Survey-design weights, clustering, and stratification were applied per HCUP guidelines. Baseline characteristics were compared with Rao–Scott χ² and weighted t-tests. Multivariable logistic regression estimated adjusted odds ratios (aOR) for mortality, incorporating patient demographics, Elixhauser comorbidities, severe PE surrogate (severe acute hypoxic respiratory failure, cardiogenic shock, and cardiac arrest) metastatic status, cancer type, payer, hospital region/teaching status/size, and year. Interaction terms evaluated heterogeneity across prespecified subgroups. Statistical significance was set at P < 0.05. Result From the 2016–2022 NIS database, we identified 37,491 hospitalizations for CAP, of which 7,804 (20.8 %) were weekend admissions and 29,687 (79.2 %) were weekday admissions. Weekend patients were more likely to present with severe PE (29.1 % vs 26.3 %, P < 0.001), and their unadjusted in-hospital mortality was slightly higher (6.6 % vs 5.9 %, P = 0.026). In multivariable logistic regression adjusting for age, sex, comorbidities, cancer type, and PE severity, weekend admission was not an independent predictor of death (adjusted odds ratio [aOR] 1.04, 95 % CI 0.93–1.16; P = 0.531; model C-statistic 0.820). Residual weekend risk clustered within specific subgroups: privately insured patients (aOR 1.41, 95 % CI 1.15–1.71), teaching hospitals (1.24, 1.00–1.52), large hospitals (1.26, 1.10–1.43), the U.S. Midwest (1.32, 1.08–1.61), patients with metastatic cancer (1.18, 1.03–1.34), and those with esophageal cancer (2.07, 1.15–3.72). All other cancer subgroups did not show statistical difference in mortality between weekdays and weekends admissions. For secondary outcomes, weekend admissions more often required mechanical ventilation (4.7 % vs 3.6 %, P = 1.4 × 10⁻⁵) but were less likely to receive first-day inferior vena cava filter placement (14.7 % vs 18.9 %, P = 0.016). Thrombolysis use, vasopressor use, length of stay, and hospitalization costs showed no significant differences between weekend and weekday admissions. Conclusions In this nationwide analysis of 37,491 CAP hospitalizations, the apparent “weekend effect” on mortality was fully attenuated after accounting for case-mix and organizational variables, indicating that overall weekend care is not intrinsically inferior. Nevertheless, clinically meaningful excess risk persists for privately-insured patients, large or teaching hospitals, Midwestern facilities, those with metastatic disease, and especially individuals with esophageal cancer. Targeted quality-improvement initiatives - such as weekend rapid-response protocols for high-risk malignancies, standardized escalation pathways, and balanced deployment of critical-care resources - are warranted to close these residual gaps and ensure equitable outcomes across all admission days.