In the current study involving 883 trauma patients, 17 of 64 potential risk variants identified systematically by previously GWAS and candidate gene association studies were used to calculate weighted genetic risk score based on random forest algorithm. Risk assessment models incorporating the wGRS and ISS were a better tool to predict the risk value of traumatic sepsis. Our current study indicated that increased wGRS was significantly associated with higher risk of traumatic sepsis. The model with only the ISS shows low discriminatory accuracy (AUC = 0.734). However, when we plus the wGRS based on 17 variants into the model, the AUC increases to 0.768 (P = 8.00 × 10− 4), indicating that genetic predictors could improve the discriminatory ability of the traditional risk model.
For major trauma patients, identifying those at high risk of sepsis then initiating appropriate treatment would improve the intensive therapy and clinical management [3, 22–24]. Outcomes following major injury are affected by many factors, containing genetic variants, inflammatory response, immune dysfunction, coagulation dysfunction, tissue damage, and abnormal host responses to different pathogenic microorganisms. Recently, majority of detection scoring systems about sepsis focused on early and accurate sepsis diagnosis, such as Insight [25], SIRS, and SOFA, which were frequently changed during the outcome process of trauma. Many studies have indicated that genetic variants might be a major and stable factor for the prediction of sepsis risk. However, evidences also indicated that a single variant is not fully responsible for sepsis development [26, 27]. In the study, we genotyped 64 genetic variants previously identified as susceptibility loci for sepsis risk. Multiple candidate genes of those polymorphisms were involved in pattern recognition receptors (PRRs), signal molecules, transcription factor, cytokines, and other immune regulated genes. PRRs are essential for recognition of microbial components and damage-associated molecular patterns, and contribute to activation of the immune system [28, 29]. Therefore, those genetic variants exhibited strong association with initiation and augmentation of sepsis [27, 30], such as the TLR1 -7202A/G (rs5743551) and TLR2 Asn248Ser (rs4833095) polymorphisms have affected the function of TLR genes, TNFA − 308G/A (rs1800629) and IL6 -572C/G (rs1800796) have affected the expression level of cytokine TNF-α and IL-6, respectively [31, 32]. Hence, genetic polymorphisms might be confirmed as potential beneficial biomarkers for evaluating sepsis risk in trauma patients. Furthermore, our data indicated these genetic biomarkers combined into the wGRS might improve the prediction accuracy.
To date, our study is the first attempt to construct and comprehensively evaluate the capacity of wGRS for risk prediction of traumatic sepsis. Despite previous studies have indicated genetic variants combined and/or into the traditional risk model could enhance the discriminatory capacity. For example, Jabandziev et al. [33] demonstrated specific combinations of five polymorphisms in the BPI (rs5743507), LBP (rs2232618), TLR4 (rs4986790), HSP70 (rs2227956), and IL-6 (rs1800795) genes appeared to predict outcome of life-threatening sepsis in children. Shimada’s study [34] indicated the combined panel of TNFA − 308G/A and IL1B -31C/T plus APACHE II score might enable more accurate prediction of outcome in septic patients. Laurentiu et al. [8] summarized a few genetic variants observed in sepsis and suggested specific genetic polymorphisms could be applied for early prediction of sepsis incidence in the future. In our previous study [35], we also indicated eight functional polymorphisms (IL1B -1470, IL1B -511, IL1B -31, IL4 -589, IL6 -572, IL8 -251, IL10 -819, and TNFA − 308) could be combined together to predict the risk of sepsis and organ dysfunction after trauma. In the current study, we revealed the incidence of traumatic sepsis has been increased with the increasing of wGRS. Genomic variants combined into the wGRS could predict the risk of traumatic sepsis (AUC = 0.619), which was improved when plus the ISS factor (AUC = 0.768). To address the increasing discriminatory power, we studied the improved value of genetic factors to the clinical factor model by NRI [36]. The improvement in risk prediction of traumatic sepsis offered by wGRS was validated (Improved 25.18%) by more detailed characterization and comparison between performances of models combined genetic variants plus ISS factor together.
This study has several notable strengths. Firstly, our study constructed the risk prediction model by the system of screening and evaluating genetic susceptibility from previous studies that has high predictive ability accuracy. Furthermore, genetic variants have several advantages as predictors, including remaining unchanged, predictable life-long risk and easy, accurate and cost-effective measurement [14, 37]. In addition, the combining of genetic and clinical factors into one model was feasible in clinical practice for trauma patients, which might improve the identification of patients at high risk for sepsis. However, some limitations should be acknowledged. Firstly, in our current study, only ISS was significantly different between sepsis and non-sepsis trauma patients and included into the prediction model, but other risk factors (antibiotic usage, blood transfusion, tracheal cannula et al.) could not be ignored in clinical practice [1], the prediction ability might be improved by adding these risk factors. Secondly, our sample size was relatively small and limited in Chinese population. Whether our findings could be extended to the general or other ethnic population needed to be determined. Thirdly, we did not take into account possible gene-environment interactions or gene-gene interactions, but many interactions exist in reality.