This study has established a nomogram. It exhibits different indexes as the independent risk factors causing the death of sepsis patients within 30 days. These include the pro. bnp, lactic acid, albumin, hematocrit, oxygenation index for the first time after hospital admission, and the average arterial pressure at admission. This model will help clinicians to analyze the prognosis of sepsis patients and formulate possible intervention measures. Notably, the model was evaluated based on different perspectives, including discrimination, calibration, and clinical effectiveness, and all their results suggest that the model has good significance。
Sepsis is caused by an inability of the immune system to eliminate invading pathogens and immune disorders [16, 17]. It is often manifested as multiple organ dysfunction, including coagulation disorder, cardiac dysfunction, renal insufficiency, nutritional disorder, etc. Many indexes such as PCT,CRP, renal insufficiency, lactic acid[20–22], pro. bnp[23, 24], albumin[25, 26], and coagulation[27, 28] have been reported to have a good effect on the diagnosis and prognosis evaluation of sepsis. This study presents that PCT, CRP, platelet, coagulation, and renal function indicators have less significance in assessing the short-term prognosis of sepsis patients. The PCT and CRP indicators are among the commonly detected indexes in patients with sepsis and are helpful to diagnose and evaluate the severity of sepsis. However, their values for prognosis evaluation are controversial. Some studies have found no significant correlation between the prognosis of severe patients and the PCT and CRP levels[28, 29]. Abnormal coagulation is common in patients with severe sepsis. Compared to previous studies, this study indicates that the initial coagulation index was not an independent risk factor for the death of patients with sepsis. Besides, it could be related to the presently increased clinical interventions (platelet and plasma transfusion), which could timely correct coagulation functioning. Previous studies have suggested that creatinine has significance in evaluating the prognosis of sepsis patients [19, 30]. However, our study shows that the initial creatinine value has little significance in evaluating prognosis. Thus, the mature and early application of the CRRT technology could be the reason for the declining renal function indicator values in assessing the prognosis of sepsis patients .
Lactic acid is one of the indexes of oxygen metabolism, which could gauge prognosis in sepsis and many other critical diseases[20–22]. Pro-bnp is an index reflecting cardiac functioning. Sepsis could trigger septic cardiomyopathy. A study has reported that the death rate of septic patients with septic cardiomyopathy complications increases . Moreover, inappropriate rehydration during treatment could also increase the pro-bnp index. Whether it is caused by sepsis or improper medical treatment, the abnormal pro-bnp increase is considered one indicator for the poor prognosis of sepsis patients. Albumin is an important nutritional index, and since its consumption in sepsis patients increases, malnutrition triggers poor prognosis [25, 26].
The low MAP suggests that sepsis patients are in a state of low perfusion shock, indicating that the disease has entered a severe stage. Elsewhere, studies have reported that the mortality rate of septic shock could reach 33.5%-61%[34, 35],, which significantly increases the mortality rate of patients with sepsis.
Many studies have explored the relationship between sepsis and acute respiratory distress syndrome (ARDS), and it is generally believed that sepsis combined with ARDS would increase the mortality rate. Nevertheless, few studies have assessed the relationship between sepsis and oxygenation index. This study suggests that the early decline of the oxygenation index is an independent risk factor for the prognosis of sepsis. Besides, ARDS, cardiac dysfunction, and excessive fluid resuscitation are the reasons for the decreasing oxygenation index and should be actively prevented and treated in clinical medicine.
Furthermore, this study suggests that hematocrit has certain significance in evaluating the short-term prognosis of sepsis patients. Whether the hematocrit is lower or higher than the normal level, it eventually affects the prognosis. Hence, correcting anemia and changing blood concentration could improve the prognosis of sepsis patients.
Unlike previous studies, the independent risk factors related to the death of patients with sepsis within 30 days have been found in this study and presented using a nomogram.
Clinically, various scoring systems had been widely used in the patients with sepsis, but the ability of those scoring systems is insufficient in accurately and reliably predicting mortality in the sepsis patient population. Arabi et al. evaluated four scoring systems in ICU patients with sepsis, reporting poor calibration for all four scores .Compared to the old scoring system,the predictive factors included in this study are objective and simple,and the model has good significance in discrimination, calibration and clinical validity.
Thus, this study could provide a short-term prognosis of sepsis patients in a more intuitive, concrete, and vivid manner when compared with previous studies. Besides, it comprehensively evaluates the model, suggesting that the model is helpful for clinical decision-making.
The limitation of this study
(1) in a retrospective study, selection bias cannot be avoided; (2) it is a single-center study, and real external verification data are lacking.