Impact of Chronic Organ Disorder Staging on Hospitalization Risk in Elderly Patients With Multimorbidity: A Retrospective Cohort Study

Introduction Multimorbidity, defined as the coexistence of two or more chronic conditions, is increasingly prevalent in the aging population and is linked to adverse health outcomes, including hospitalization. Chronic organ disorder (COD) is a proposed framework in Japan to assess multimorbidity by categorizing organ dysfunction stages. This study investigates the association between COD stages and hospitalization rates in elderly patients with multimorbidity. Method A retrospective cohort study was conducted at the Internal Medicine Department of Unnan Municipal Hospital. Patients aged 18 and older with multimorbidity, defined as having two or more chronic diseases, who visited the clinic from April to September 2022 were included. COD stages were classified from A to E, representing increasing severity. Logistic regression analysis was used to evaluate hospitalization-related factors, including age, BMI, serum albumin, and COD stages. Results Among 568 patients, 66 (11.6%) were hospitalized. Hospitalized patients were older (75.5 vs. 58.8 years, p < 0.001), had lower BMI (20.65 vs. 22.21 kg/m², p = 0.003), and lower serum albumin levels (3.70 vs. 3.96 g/dL, p < 0.001). Advanced COD (Stage B or above) was associated with an increased risk of hospitalization (OR: 1.86, 95% CI: 1.01-3.45, p = 0.048). Age ≥75 years (OR: 2.93, 95% CI: 1.55-5.54, p < 0.001) and low BMI were also significant predictors. Conclusion This study demonstrates that advanced COD stages, age, and low BMI are significant predictors of hospitalization in patients with multimorbidity. Comprehensive COD assessment aids in identifying high-risk patients and potentially guides preventive interventions to reduce hospital admissions.