Impact of nutritional status and systemic immune-inflammation index on mortality in patients with acute myocardial infarction

Abstract

Abstract Background It has been known that malnutrition and elevated inflammatory markers are associated with clinical outcome in patients with acute myocardial infarction (AMI). However, few studies have investigated the association between nutritional status, inflammatory markers and survival in patients with AMI. Purpose The aim of this study is to investigate combined impact of nutritional status and systemic immune-inflammatory index (SII) on outcome in patients with AMI. Methods We examined 1,984 patients (mean age = 64 ± 12 year-old, 1,493 males) admitted for AMI. Nutritional assessment was evaluated at the admission by geriatric nutritional risk index (GNRI) calculation. Malnutrition was defined as GRNI <92. We calculated SII from the equation, SII = P x N/L, where P, N and L are peripheral blood platelet, neutrophil and lymphocyte counts per liter at the time of admission, respectively. The primary endpoint was all-cause mortality at 1-year. Results GNRI was significantly correlated with SII (r = -0.135, p<0.001). GNRI (95.2 ± 8.4 versus 102.7 ± 7.3) was significantly lower, whereas SII (1,906.9 ± 2,016.0 x 109 cells/L versus 1,100.9 ± 981.6 x 109 cells/L) was significantly higher in non-survivors. Patients with malnutrition had significantly higher mortality compared with patients without malnutrition (19.2% versus 4.3%, log-rank p <0.001). In receiver operating characteristics curve analysis, area under the curve of SII for predicting all-cause mortality was 0.625. The optimum cut-off point for SII for a favorable prognosis was determined to be 1,425 x 109 cells/L. Patients with high SII had significantly higher mortality (9.6% versus 4.2%, log-rank p<0.001). The patients were divided into four groups based on GNRI & SII; high GNRI &low SII (Group 1), high GNRI & high SII (Group 2), low GNRI & low SII (Group 3), and low GNRI & high SII (Group 4). In Kaplan-Meier survival curve, all-cause mortality was significantly higher in Group 4 compared with Group 1, Group 2, and Group 3 (3.5% versus 6.7% versus 14.1% versus 25.6%, log-rank p<0.001; Figure). In Cox-proportional hazards model, compared with Group 1 (1, reference), Group 2 (HR 1.64, 95% CI 1.02 – 2.63; p=0.038), Group 3 (HR 1.97, 95% CI 1.06 – 3.68; p=0.032), and 4 (HR 4.17, 95% CI 2.40 – 7.24; p<0.001) was an independent predictor of all-cause mortality after adjusting for confounding variables. Conclusion Nutritional status was significantly correlated with immune-inflammatory index. Malnutrition and high SII was independent predictors of overall survival in patients with AMI.