Prognostic factors for ARDS: clinical, physiological and atypical immunodeficiency

Abstract

Background: The risk factors affecting the prognosis of acute respiratory distress syndrome (ARDS) in adults were investigated. The aim was to identify new predictors of prognosis in ARDS patients, including those with clinical, pathophysiological, and atypical immunodeficiency. Methods: ARDS patients were retrospectively included. Patients were grouped and analysed according to different oxygenation index grades and prognosis, and the factors influencing prognosis and survival were analysed. Adolescent patients, patients with typical immunodeficiency and patients who died within 24 hours after being diagnosed with ARDS were excluded. The predictive value for mortality was determined by Cox proportional hazard analysis. Results: In total, 201 patients who fulfilled the Berlin definition of ARDS were included. The severity of critical illness on the day of enrolment, as measured by the Acute Physiology and Chronic Health Evaluation (APACHE) II score (P=0.016), Sequential Organ Failure Assessment (SOFA) score (P=0.027), and PaO 2 /FiO 2 (P=0.000), worsened from mild to severe ARDS. Compared with survivors, non-survivors had significantly older age and higher APACHE II and SOFA scores. Moreover, significantly lower lymphocyte/neutrophil ratios and leukocyte counts were found in non-survivors than in survivors (P=0.008, P=0.012). Furthermore, there was a moderate positive correlation between the lymphocyte/neutrophil and PaO 2 /FiO 2 ratios (P=0.023). The area under the curve (AUC) for the lymphocyte/neutrophil ratio was significantly greater than those for the body mass index (BMI) alone, PaO 2 /FiO 2 ratio alone, and lymphocyte/neutrophil ratio alone for predicting 100-day survival in patients with ARDS (P=0.0062, 0.0001, and 0.0154). Age (per log 10 years), BMI<24, the SOFA score, leukocyte count, and the lymphocyte/neutrophil ratio were independent predictors of 28-day mortality in ARDS patients. Moreover, ARDS patients with a lymphocyte/neutrophil ratio <0.0537 had elevated 28-day mortality (P=0.0283). Old age affected both 28-day and 100-day mortality (P=0.0064,0.0057). Conclusions: Age (per log 10 years), BMI<24, SOFA score, lymphocytes, and the lymphocyte/neutrophil ratio were independent predictors of 100-day mortality in patients with ARDS. The lymphocyte/neutrophil ratio may represent a potential molecular marker to evaluate atypical immunosuppression or impairment in patients with ARDS.