Exploring the relationship between malnutrition and the Systemic Immune-inflammation Index in older inpatients: a study based on Comprehensive Geriatric Assessment

Background: Malnutrition is a prevalent and major challenge among senior citizens, possibly due to the continual low-grade inflammatory state of the body. A novel inflammatory parameter, the systemic immune-inflammation index (SII), is highly valuable in evaluating and predicting the prognosis of a wide range of diseases. This study aims to explore the significance of the SII in assessing malnutrition in older inpatients. Methods: This retrospective study included 500 senior hospitalized patients who met the inclusion and exclusion criteria from the Comprehensive Geriatric Assessment database of the First Hospital of Jilin University. The Mini-Nutritional Assessment (MNA) questionnaire was used to evaluate the nutritional status of patients. The SII was calculated using complete blood counts, and we performed natural logarithm transformation of the SII [ln(SII)]. Multivariable logistic regression analysis was used to identify the association between ln(SII) and undernutrition. To ensure the stability of the findings, a sensitivity analysis was conducted. Results: The 500 patients had a mean age of 77.29±9.85 years, and 68.6% were male. In accordance with the MNA, 30.4% of the patients were malnourished or at risk of malnutrition, and patients in this group had considerably greater levels of ln(SII) than patients with normal nutritional status ( P < 0.001). Age, history of coronary heart disease, body mass index (BMI), calf circumference, body composition parameters, scale testing results, and polypharmacy were all added sequentially to a multivariable logistic regression model. The findings demonstrated that ln(SII) was an independent risk factor for the possibility of malnutrition or undernutrition in older individuals. (OR 3.984, 95% CI = 2.426-6.543, P < 0.001). Other metrics from the geriatric comprehensive assessment, including BMI, calf circumference, fat ratio, activities of daily living and instrumental activities of daily living, and geriatric depression scale scores, were also independently correlated with nutritional status. Conclusions: According to our research, a high SII is an independent predictor of older inpatient malnutrition, and the SII aids in screening for malnutrition and may be a potential target for intervention. Geriatric comprehensive assessment parameters such as BMI, calf circumference, fat ratio, activities of daily living and depression were also linked to malnutrition.