Weekend admission and outcomes in cancer-associated pulmonary embolism: a cross-sectional national inpatient sample study, 2016-2022.

The "weekend effect" has been variably associated with outcomes in acute pulmonary embolism (PE), but its relevance in cancer-associated PE remains uncertain. Among U.S. hospitalizations for cancer-associated PE, is weekend admission independently associated with in-hospital mortality, and do PE-related interventions differ by day of admission? Retrospective cross-sectional study using the HCUP National Inpatient Sample (2016-2022). Adults (≥ 18 years) hospitalized with a principal diagnosis of PE and concomitant malignancy were included. Weekend admission was Saturday-Sunday. Survey-weighted analyses in R generated national estimates. Survey-weighted logistic regression estimated adjusted odds ratios (ORs) for in-hospital mortality. We compared PE-related therapies/procedures (mechanical ventilation, vasopressors, systemic thrombolysis, and inferior vena cava [IVC] filter placement), including hospital-day-1 use (0 days to procedure). We identified 37,491 unweighted cancer-associated PE hospitalizations, representing approximately 187,455 weighted national hospitalizations, of which 7,804 unweighted hospitalizations (20.8%) were weekend admissions. Weekend admissions had higher acuity, with the administrative marker of high-acuity PE more frequent on weekends (29.1% vs. 26.3%), and higher unadjusted mortality (6.6% vs. 5.9%). In the fully adjusted model (N = 36,408; deaths = 2,210), weekend admission was not associated with mortality (adjusted OR 1.04, 95% CI 0.93-1.16). Mechanical ventilation was more frequent on weekends (4.7% vs. 3.6%). Thrombolysis and overall IVC filter use were similar, but hospital-day-1 IVC filter placement was less common on weekends (14.7% vs. 18.9%). Higher unadjusted weekend mortality in cancer-associated PE appears largely explained by case mix and severity rather than weekend admission itself.