Associations of multimorbidity with mortality, hospital stay, and hospitalization costs in Chinese surgical patients: a retrospective cohort study

BACKGROUND: Multimorbidity (≥ 2 chronic conditions) is rising in aging populations. China reports over 80 million surgeries annually. This study investigates health burdens of multimorbidity in Chinese surgical patients. It highlights its impact on postoperative outcomes using large-scale data across diverse surgical types, addressing a key gap in existing evidence. METHODS: This retrospective cohort study includes adult patients who underwent non-cardiac surgery in 2023 at a major national-level medical center in China. Patients were categorized by having no morbidity, one morbidity, or multimorbidity. Outcomes included in-hospital mortality, hospital stay, and hospitalization costs. Multivariable regression analyses assessed associations, and identified disease combinations with the highest risk and costs. RESULTS: Among 37,084 surgical patients, 17.4% had multimorbidity. Their in-hospital mortality rate was 1.5%, compared to 0.7% with one morbidity and 0.2% with none. Median hospital stays were 8, 7, and 6 days, respectively. Patients with multimorbidity had higher median hospitalization costs ($6,485), compared to $4,975 for one morbidity, and $3,714 for none. Multivariable analysis demonstrated multimorbidity was significantly associated with higher postoperative mortality (P < 0.001), longer hospital stays (P < 0.001), and increased cost (P < 0.001). Hypertension combined with chronic kidney disease and anemia posed the highest mortality risk and costs. CONCLUSIONS: Multimorbidity was linked to a 2 to 7-fold increase in mortality, 1-2 extra hospital days, and $1,510-2,771 higher costs compared with patients having one or no morbidities. This large-scale annual study in China underscores the need for enhanced preoperative evaluations and tailored care strategies to improve outcomes and reduce costs for multimorbid surgical patients.