The value of calculated inflammation indices for assessing the risk of hospital mortality in infective endocarditis

Abstract The role of calculated indices of inflammation (neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and systemic immune-inflammation index (SII)) has been poorly studied in patients with infective endocarditis (IE). Aim: to investigate the value of calculated inflammation indices (neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and systemic immune-inflammation index (SII)) to assess the risk of hospital mortality in patients with infective endocarditis (IE). Materials and methods: The study included 345 patients with IE (DUKE 2009, 2015, 2023) from an emergency hospital in 2012-2022. Median age: 56.0 [37.0-71.0] years, ≥60 years: 60.0% (n=207), men: 65.2% (n=225), Charlson index: 5.0 [2.0-8.0]. Laboratory and instrumental studies, echocardiography, blood culture and calculation of indices (neutrophil/lymphocyte, platelet/lymphocyte and neutrophil*platelet/lymphocyte) were performed upon admission and in 7 days. Results: Among the examined patients with IE, at admission and in dynamics, a significant decrease was revealed in the level of NLR (6.6 [3.6-11.1] and 2.7 [2.2-7.1], p<0.05), while significant changes in PLR values (135.8 [82.9-223.2] and 143.2 [91.5-226.2], p>0.05) and SII (868.8 [430.4-1785.7] and 899.6 [462.0-1419.4], p>0.05) were not obtained. 109 (31.6%) patients died during hospitalization. In the group of the deceased, compared with the survivors, significantly higher values of NLR were noted both at admission (7.5 [4.5-12.6] vs. 5.6 [3.0-10.1], p<0.05) and in dynamics (9.3 [5.3-16.1] vs. 2.3 [2.0-6.5] p<0.05). Attention was drawn to the increase in NLR dynamics in the group of the deceased and its decrease in the group of survivors. The levels of SII in the group of the deceased were significantly higher compared with the survivors both at admission (1265 [497.8-2535.1] vs. 856.4 [410.2-1625.4], p<0.05) and in dynamics (1150.5 [523.6-2529.8] vs. 863.6 [422.0-1340.1], p<0.05), without increasing trends. PLR levels in the deceased group were significantly lower than in the survivors both at admission (111.4 [63.9-204.2] vs. 140.8 [92.9-224.2], p<0.05) and in dynamics (119.3 [61.6-218.9]) vs. 146.7 [98.5-232.2], p<0.05). The method of step-by-step logistic regression analysis revealed independent predictors of hospital mortality: high values of neutrophil-to-lymphocyte ratio ≥ 20 – [OR 9.5 (95% CI 1.83-49.37), p=0.007] and systemic immune-inflammation index ≥2314.0 [OR 5.86 (95% CI 1.98-17.28), p=0.001], as well as low values of platelet-to-lymphocyte ratio <82.8 [OR 2.8 (95% CI 1.2-6.3), p=0.015]. Conclusion: Calculated inflammation indices are easy to get to define patients at high risk of death in hospital. The risk of hospital mortality increases with values of the neutrophil-to-lymphocyte ratio ≥ 20 by 9.5 times, with values of the systemic immune-inflammation index ≥2314.0 – by 5.9 times, with values of the platelet-to-lymphocyte ratio ≤82.8 – by 2.8 times.