Relationship between low hemoglobin levels and mortality in patients with septic shock

Hemoglobin levels are a critical parameter for oxygen delivery in patients with shock. On comparing target hemoglobin levels upon transfusion initiation, the correlation between the severity of decrease in hemoglobin levels and patient outcomes remains unclear. We evaluated the association between initial hemoglobin levels and mortality in patients with septic shock treated with protocol-driven resuscitation bundle therapy at an emergency department.

Data of adult patients diagnosed with septic shock between June 2012 and December 2016 were extracted from a prospectively compiled septic shock registry at a single academic medical center. Patients were classified into four groups according to initial hemoglobin levels: ≥9.0 g/dl, 8.0-8.9 g/dl, 7.0-7.9 g/dl, and <7.0 g/dl. The primary endpoint was 90-day mortality.

In total, 2,265 patients (male, 58.3%; median age, 70.0 years [interquartile range, 60 to 78 years]) with septic shock were included. For the four groups, 90-day mortality rates were as follows: 29.1%, 43.0%, 46.5%, and 46.9% for ≥9.0 g/dl (n=1,808), 8.0-8.9 g/dl (n=217), 7.0-7.9 g/dl (n=135), and <7.0 g/dl (n=105), respectively (P<0.001). Multivariate logistic regression showed that initial hemoglobin levels were an independent factor associated with 90-day mortality and mortality proportionally increased with decreasing hemoglobin levels (odds ratio [OR], 1.88; 95% confidence interval [CI], 1.36 to 2.61 for 8.0-8.9 g/dl; OR, 1.97; 95% CI, 1.31 to 2.95 for 7.0-7.9 g/dl; and OR, 2.35; 95% CI, 1.52 to 3.63 for <7.0 g/dl).

Low hemoglobin levels (<9.0 g/dl) were observed in approximately 20% of patients with septic shock, and the severity of decrease in these levels correlated with mortality.