Charlson comorbidity index in elderly patients affected by septic shock: results from the SOFA-T collaborative group

Background: elderly patients affected by severe sepsis and septic shock (SS) are often managed in internal and emergency medicine departments. Sequential organ failure assessment (SOFA) score is commonly used to predict short and long-term prognosis in these subjects. Less is known on the impact of chronic comorbidities in this subset. With this substudy, we aimed to evaluate the role of Charlson comorbidity index (CCI) in predicting in-hospital death in a cohort of elderly patients affected by SS. Methods:in the period 01/2015-12/2017 we enrolled all the consecutive patients admitted for SS in two Internal Medicine departments with expertise in critical care medicine. For each patient we evaluated, at the admission: (1) SOFA score (2) sex, age, troponin I (TnI), PCR and procalcitonin (PCT), (3) comorbidities and (4) CCI. The main outcome was defined as in-hospital death for SS. The association between CCI and the main outcome was explored with a binary logistic regression model evaluating in-hospital death as outcome, SOFA score, CCI as predictors and sex, PCR, PCT and TnI as covariates. Results: we obtained a final sample of 390 subjects (age:79,6±11,4; males:49,2%) with 144 (36,9%) deaths. SOFA score ranged 0-15(7), CCI ranged 0-13(7). Mean CCI was 7,11(±2,40) among survivors and 6,75(±2,05) among dead patients (p=0,195). In the binary logistic model, we observed that SOFA score (p=0,006), TnI (p=0,004) and PCT (p=0,040) were significantly associated with the outcome, while CCI (p=0,291), sex (p=0,506) and PCT (p=0,834) were not associated to a worse prognosis. ROC curve analysis confirmed a non-significant association between CCI and prognosis (AUC:0,443; 95%CI:0,395-0,586,p=n. s. ). Discussion: CCI, a marker of patient’s age and chronic complexity, is not associated to a worse short-term prognosis among patients affected by SS, while the acute organ impairment synthesized by SOFA score is strongly associated to in-hospital death in this group.