Neutrophil-to-lymphocyte ratio (NLR) is associated with increased 30-day mortality in patients with sepsis-induced myocardial injury: analysis based on MIMIC-IV database

Abstract Background Myocardial injury is a serious complication of sepsis. It is necessary to explore the risk factors that affect the prognosis of sepsis-induced myocardial injury. Many studies have investigated the role of the neutrophil-to-lymphocyte ratio (NLR) in the early diagnosis and prognostic prediction of sepsis, but few foucus on sepsis induced myocardial injury. We assessed NLR in patients with sepsis-induced myocardial injury to find the relationship between NLR and 30-day mortality. Methods Patients with sepsis induced myocardial injury who had neutrophil counts and lymphocyte counts detected within 48 hours of admission were screened from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Patients were divided into three groups according to NLR in tertiles: the lower tertile group (NLR < 6.29), the second tertile group (NLR 6.29–13.86) and the upper tertile group (NLR > 13.86). Kaplan-Meier curve and multivariate Cox regression model were constructed. The differential effect of age on the relationship between NLR in tertiles and 30-day mortality was examined using an interaction term (difference in differences analysis). Results This study eventually included 1690 adult sepsis-induced myocardial injury patients. Compared with the surviving group, NLR of the death group was higher [9.11(5.27–16.91) vs11.5(6.43–19.75), p < 0.001]. Kaplan-Meier survival analysis showed significantly higher mortality among participants in the upper NLR tertile than among those in the reference of lower NLR tertile [191(32.43%) vs.108(21.14%), P < 0.001]. After adjustment for all clinical variables, multivariate Cox regression analysis showed the same trend (HR = 1.17; 95% CI 1.04–1.32; P = 0.01). When examining the differential effect of age, 30-day mortality was significantly higher in the upper tertile than in the lower tertile as age increased. Conclusions NLR was associated with higher 30-day mortality in patients with sepsis-induced myocardial injury.