Electrolyte abnormalities and arrhythmia-associated inpatient deterioration in hospitalized cancer patients: National patterns in the National Inpatient Sample, 2018–2022.

Abstract

e23162 Background: Electrolyte abnormalities are frequent during cancer hospitalizations, but their independent association with arrhythmias and downstream inpatient deterioration remains incompletely characterized at a national level. This study evaluated the relationship between common electrolyte disorders and arrhythmias, severity, organ support, mortality, and resource utilization during cancer hospitalizations. Methods: A retrospective serial cross-sectional analysis was conducted using adult hospitalizations with a principal diagnosis of malignancy in the 2018 to 2022 National Inpatient Sample with discharge-level survey weighting. Electrolyte disorders were identified using ICD-10-CM codes for hyponatremia (E87.1), hypokalemia (E87.6), hyperkalemia (E87.5), and hypocalcemia (E83.51). The primary outcome was any arrhythmia (I47 to I49). Secondary outcomes included extreme All Patient Refined Diagnosis Related Group severity, mechanical ventilation, in-hospital mortality, length of stay, and hospitalization cost. Survey-weighted multivariable models adjusted for demographics, payer, ZIP-code income quartile, admission type, cancer subtype, hospital characteristics, and year. Results: Among 961,848 unweighted cancer hospitalizations representing 4.81 million admissions nationally, 24.9% had at least one electrolyte disorder. Arrhythmias occurred in 14.2% overall and were more frequent with electrolyte disorders (18.0% vs 12.9%). After adjustment, any electrolyte disorder was independently associated with arrhythmia (adjusted odds ratio (aOR) 1.48, 95% CI 1.46 to 1.50), extreme severity (aOR 2.27, 95% CI 2.20 to 2.35), mechanical ventilation (aOR 2.60, 95% CI 2.53 to 2.68), and in-hospital mortality (aOR 2.53, 95% CI 2.42 to 2.64). Hyperkalemia demonstrated the strongest associations, including arrhythmia (aOR 1.77), mechanical ventilation (aOR 3.32), and mortality (aOR 4.12). Admissions with any electrolyte disorder had longer length of stay (9.8 vs 5.7 days) and higher costs ($29,013 vs $21,007). Conclusions: Electrolyte abnormalities are common during cancer hospitalizations and are independently associated with arrhythmias, severe illness, mechanical ventilation, mortality, and increased resource utilization. These findings highlight metabolic instability as a clinically actionable marker of high-acuity inpatient risk in oncology populations.