Discharge trajectories and 30-day readmission risk in hospitalized breast cancer patients with malignant pleural effusion: A National Readmissions study.

e13104 Background: Malignant pleural effusion (MPE) is a common complication of advanced breast cancer and a frequent cause of hospitalization, yet national data on early unplanned readmission after pleural drainage are limited. We examined patterns and predictors of 30-day readmission among hospitalized breast cancer patients with MPE. Methods: We performed a retrospective cohort study using the 2016–2017 Nationwide Readmissions Database. Adult hospitalizations with breast cancer and MPE were identified using ICD-10-CM codes; index admissions were defined as the first qualifying hospitalization per patient, excluding in-hospital deaths. The primary outcome was 30-day all-cause readmission; secondary outcomes included time to readmission and primary readmission diagnosis. Discharge disposition was classified as home without services, home with services, post-acute care, or other. Survey-weighted multivariable logistic regression was used, adjusting for demographics, payer, income quartile, length of stay, acute illness severity (APR-DRG), mortality risk, Charlson comorbidity index, and hospital characteristics. Results: Among 6,550 index hospitalizations, 8.9% resulted in 30-day readmission. Median time to readmission was 16 days (IQR 10–22). Discharge disposition was home without services (43.5%), home with services (39.7%), and post-acute care (15.5%). Cancer progression or metastases accounted for most readmissions (75%), followed by respiratory/pleural complications (7%) and infection/sepsis (4%). Readmission rates were highest among patients discharged home without services (12.2%) and lowest among those discharged to post-acute care (3.2%). In adjusted analyses, discharge to home with services (aOR 0.75, 95% CI 0.60–0.93) and post-acute care (aOR 0.39, 95% CI 0.26–0.59) were associated with lower readmission risk versus home without services. Older age (aOR 0.98/year, 95% CI 0.98–0.99) and longer index length of stay (aOR 0.92/day, 95% CI 0.90–0.95) were independently associated with reduced readmission risk. Conclusions: Nearly one in eleven hospitalized breast cancer patients with MPE experienced early readmission, typically within two weeks of discharge. Discharge disposition defined distinct inpatient trajectory phenotypes with markedly different readmission risks, highest among patients discharged home without services. These findings suggest that discharge destination reflects more than illness severity and represents an actionable transition point, while post-acute care and home services are protective. Older age and longer hospitalization were independently associated with lower readmission risk, noting the importance of discharge readiness and care transitions. Targeted discharge planning and post-acute support may reduce avoidable readmissions in this high-risk population.