Effect of Relative Decrease in Blood Hemoglobin Concentrations on Postoperative Morbidity in Patients Who Undergo Major Gastrointestinal Surgery

IMPORTANCE: Delta hemoglobin (ΔHb), defined as the difference between the preoperative hemoglobin (Hb) level and the nadir Hb level during a patient's hospitalization, may be associated with adverse outcomes even if the absolute level of Hb remains greater than the transfusion threshold of 7 g/dL. OBJECTIVE: To evaluate the association between ΔHb and morbidity in patients who undergo major gastrointestinal surgery as an independent factor or combined with the nadir Hb concentration. DESIGN, SETTING, AND PARTICIPANTS: Retrospective review of prospectively collected data on patients who underwent pancreatic, hepatic, or colorectal resection from January 1, 2010, through April 30, 2014, at Johns Hopkins Hospital were included in the study. Data regarding the ΔHb concentration following surgery, nadir Hb level, and overall perioperative blood use were obtained and analyzed. Multivariable-adjusted logistic regression models were used to identify the preoperative factors associated with ΔHb and the effect of ΔHb on perioperative morbidity. The study and data analysis took place from January 22 through February 20, 2015. INTERVENTIONS: Major gastrointestinal surgery and packed red blood cell transfusion. MAIN OUTCOMES AND MEASURES: Overall morbidity and ischemic-specific complications. RESULTS: Of the 4669 patients who underwent major gastrointestinal surgery, the median ΔHb level after surgery was 40%. Patients with multiple comorbidities (American Society of Anesthesiologists Physical Status score of 3-4: odds ratio OR, 1.96; 95% CI, 1.30-2.97; P <.001; ≥3 coexisting medical conditions: OR, 1.62; 95% CI, 1.08-2.42; P = .001) and those who underwent pancreatic surgery (OR, 1.98; 95% CI, 1.18-3.33; P = .01) were at increased risk of having a ΔHb of 50% or greater. Compared with patients who had a ΔHb level of less than 50% and a nadir Hb level of 7 g/dL or greater, patients with a ΔHb level of 50% or greater whose nadir Hb level was less than 7 g/dL were at a high risk of developing postoperative complications (OR, 6.60; 95% CI, 4.34-10.03; P < .001); in particular, a ΔHb level of 50% or greater was strongly correlated with a risk of ischemic complications, even if the nadir Hb level was 7 g/dL or greater (OR, 5.68; 95% CI, 1.44-22.39; P = .01). CONCLUSIONS AND RELEVANCE: A ΔHb level of 50% or greater following gastrointestinal surgery was associated with complications, especially ischemic adverse events, even if the nadir Hb level remained at 7 g/dL or greater.