Linear Association Between Hypoalbuminemia and Increased Risk of Acute Respiratory Distress Syndrome in Critically Ill Adults

We hypothesized that low serum albumin would contribute to pulmonary edema formation, thereby independently increasing the risk of developing acute respiratory distress syndrome in critically ill patients. DESIGN: Retrospective analysis of prospective cohort. SETTING: Medical, surgical, and cardiovascular ICUs at Vanderbilt University Medical Center. PATIENTS: Patients (n = 993) with serum albumin measured for clinical reasons within 24 hours of study enrollment on ICU day 2 were included. MEASUREMENTS AND MAIN RESULTS: The primary outcome was presence of acute respiratory distress syndrome at any time during the first 4 days in the ICU, as defined by the Berlin definition. Secondary outcomes included ventilator-free days and ICU length of stay. In an unadjusted analysis, lower serum albumin levels were associated with a higher occurrence rate of acute respiratory distress syndrome (p < 0.001). In a multivariable analysis controlling for prespecified confounders, lower serum albumin was independently associated with an increased risk of acute respiratory distress syndrome (odds ratio, 1.48 per 1-g/dL decrease in albumin; 95% CI, 1.14–1.94; p = 0.004). Additionally, lower serum albumin was associated with increased mortality (odds ratio, 1.56 per 1-g/dL decrease in albumin; 95% CI, 1.19–2.04; p = 0.001), increased ICU length of stay (incidence rate ratio, 1.19; 95% CI, 1.15–1.23; p < 0.001), higher Sequential Organ Failure Assessment score (p < 0.001), and fewer ventilator-free days (incidence rate ratio, 1.21; 95% CI, 1.19–1.24; p < 0.001). CONCLUSIONS: Among adult ICU patients, lower serum albumin was independently associated with increased risk of acute respiratory distress syndrome after controlling for severity of illness and potential confounders. These findings support the hypothesis that low plasma oncotic pressure contributes to pulmonary edema formation in patients at risk for acute respiratory distress syndrome, independent of severity of illness.