Prospective Evaluation of Serial Protein Biomarker Measurements in Sepsis-Induced Acute Respiratory Distress Syndrome

Abstract

RATIONALE: Protein biomarkers including soluble receptor for advanced glycation end-products (sRAGE), angiopoietin-2 (Ang- 2), and surfactant protein-D (SP-D) have been studied for diagnosis or prognostication in acute respiratory distress syndrome (ARDS). However, prior studies of ARDS biomarkers often included heterogeneous populations, and rarely examined serial measurements. Our aim was to determine the association between serially measured sRAGE, Ang-2, and SP-D levels and ARDS development in patients with sepsis. METHODS: Adult patients admitted to the medical ICU at Grady Memorial Hospital within 72 hours of sepsis diagnosis were enrolled into this prospective observational cohort study within 48 hours of ICU admission. Patients who already had ARDS at the time of screening were excluded. After obtaining informed consent, serial plasma samples were collected on day 1, 2, and 3 of enrollment, and were analyzed for sRAGE, Ang-2, and SP-D levels using ELISA. The patients were followed for up to 28 days for relevant clinical characteristics and outcomes. The primary outcome was ARDS development according to the Berlin Definition. The secondary outcome was mortality. Pulmonary sepsis was defined as the primary infection being pneumonia (including COVID19) or aspiration pneumonia. The biomarker levels and their changes from day 1 to days 2/3 were compared between those who developed ARDS versus those who did not. RESULTS: Among 80 patients with sepsis enrolled between September 1, 2020 and June 22, 2021, 15 patients (18.8%) developed ARDS and 65 patients (81.3%) did not. ARDS patients had higher proportions of pulmonary sepsis (14/15 [93.3%] vs. 30/65 [46.2%], p=0.001) and COVID19 (7/15 [46.7%] vs. 7/65 [10.8%], p=0.003) compared to non-ARDS patients. ARDS patients had higher SP-D levels on days 1 and 2, and had a greater increase in sRAGE levels from day 1 to day 3, compared to non-ARDS patients (Figure 1A- 1B). Within the ARDS group, those who died had higher sRAGE levels on day 1 compared to those who survived (Figure 1C). CONCLUSIONS: In this analysis, ARDS patients had higher SP-D and a greater increase in sRAGE over time compared to non- ARDS patients. Non-survivors of ARDS also had higher sRAGE compared to survivors. Our findings suggest that early serial biomarker measurements may be useful for identifying sepsis patients at risk of developing ARDS and adverse clinical outcomes, and for risk stratifying sepsis patients in ARDS clinical trials focused on early therapeutics and prevention. Larger studies are needed for more detailed analyses and confirmation of these findings.