Association of sarcopenia with systemic immune inflammatory index in elderly patients

The relationship between the immune inflammatory index (SII) and sarcopenia in older patients, specifically in terms of muscle mass and relative strength, was assessed. The SII has shown promising predictive ability and high efficacy in identifying decreased muscle function among older individuals.

BACKGROUND. In elderly people, sarcopenia can lead to a decrease in functional activity and the ability to perform self-care activities, as well as an increased risk of falling. A general blood test is a common laboratory test that can be used to measure various components that can act as markers for inflammation. The SII index, which is calculated by multiplying the number of platelets by neutrophils and dividing by lymphocytes, is more accurate than C-reactive protein in predicting coronary heart disease. It can also effectively predict the development and progression of heart failure. However, the relationship between sarcopenia and the SII index has not yet been fully investigated.

THE OBJECTIVE OF THE STUDY ― to investigate the relationship between the inflammatory index SII (platelet-neutrophil ratio/lymphocyte count) and muscle mass and strength.

MATERIALS AND METHODS. The study included 65 elderly men with an average age of 70.4 ± 3.2 year. Sarcopenia was diagnosed using the EWGSOP criteria. The participants were divided into two groups: group 1 included 32 men with sarcopenia, and group 2 included 33 men without sarcopenia. The inclusion criteria were: the age of the patients was 60–74 years, and all stages of the study had been completed.

Muscle mass index (MMI) was determined by dividing muscle mass by body mass index (BMI). For men, an MMI below 0.789 was considered low. Grip strength was measured by squeezing a dynamometer in each hand 3 times for 5 seconds, and the average value was taken. The elbow was positioned at a right angle to the body. Relative Strength Index (RSI) was calculated by dividing dominant arm muscle strength by BMI.

Statistical analysis was performed using ROC analysis to evaluate MMI in predicting low muscle mass and strength risk. Spearman's correlation analysis was used to assess the relationship between SII, MMI, and muscle strength.

RESULTS. Patients with sarcopenia had a significantly higher BMI (p < 0.001, mean (32.03 ± 6.28) kg/m²) compared to those without sarcopenia (mean (25.98 ± 5.03) kg/m²). They also had lower BMI (mean 0.68 ± 0.09 vs 0.87 ± 0.06) and BMI (1.12 ± 0.17 vs 1.52 ± 0.23). An increase in BMI was associated with a decrease in RSI.

Patients without sarcopenia had lower platelet and lymphocyte counts. The SII value was significantly higher in patients with sarcopenia (548.36 ± 232.63) compared to those without (414.42 ± 205.25, p<0.001). The area under the ROC curve for SII predicting a decrease in BMI was 0.723 ± 0.054, indicating a 74.2% diagnostic effectiveness. For RSI, the area was 0.852 ± 0.035, indicating an 82.5% diagnostic efficiency. SII also maintained a significant negative correlation with IMM, both as a continuous and categorical variable.

CONCLUSION. The SII index has demonstrated reliable predictive ability and high efficiency in detecting decreased muscle function in elderly patients.