Effects of age on the use of lactate clearance rate to predict prognosis in septic shock patients

Objective To explore the effects of age on the use of lactate clearance rate (LCR) to predict prognosis in septic shock patients. Methods Septic shock patients who were admitted into the intensive care unit (ICU) of the Affiliated Hospital of Xuzhou Medical University from January 2015 to August 2018, with complete clinical data, were selected for retrospective analysis. According to their ages, they were divided into a non-elderly group (aged 18-74 years) and an elderly group (≥75 years old). Moreover, according to the outcome of hospitalization, the patients were divided into a survival group and a death group. The level of arterial blood lactate (Lac) was measured when the patients were diagnosed with septic shock (0 h), and 12 h and 24 h after treatment, while the LCRs at 12 h and 24 h were calculated. The scores of Acute Physiology and Chronic Health Evaluation Ⅱ (APACHE Ⅱ) and Sequential Organ Failure Assessment (SOFA), the length of hospitalization stay and outcomes were recorded. The differences of above indicators in each group were analyzed. Results A total of 483 septic shock patients were collected, in which 286 patients met inclusion criteria, including 111 cases in the elderly group and 175 in the non-elderly group. There were 61 cases (55.0%) of death in the elderly group and 55 cases (31.4%) of death in the non-elderly group. The COX regression analysis and survival time curve showed that age was an independent risk factor for the prognosis of septic shock patients. The risk of death in the elderly group was 1.95 times higher than that in the non-elderly group. Patients in the death group in different age ranges presented higher APACHE Ⅱ scores, SOFA scores, and blood Lac levels as well as lower 24 h LCR than those in the survival group (P 0.05). APACHE Ⅱ score, SOFA score and blood Lac level were positively related with hospitalization mortality, but negatively related with LCR. Conclusions Age, APACHE Ⅱ score, SOFA score, Lac level and LCR are related factors of hospitalization outcome, where age is an independent risk factor for the prognosis of septic shock patients. LCR cannot be used to accurately evaluate the prognosis of elderly patients with septic shock. Key words: Septic shock; Lactate clearance rate; Prognosis; Age