Preoperative Hemoglobin Level as a Predictor of Survival After Coronary Artery Bypass Grafting

Abstract

Background— The predictive value of the preoperative hemoglobin value after coronary artery bypass grafting (CABG) has not been well established. We studied how the preoperative hemoglobin level affects the survival of patients after CABG. Late mortality was compared with that of a general population. Methods and Results— Early and late mortality of all consecutive patients undergoing isolated CABG between January 1998 and December 2007 were determined. Patients were classified into 4 groups stratified by preoperative hemoglobin level. The cutoff point for anemia was 13 g/dL for men and 12 g/dL for women. Expected survival of a matched general Dutch population cohort was obtained from the database of the Dutch Central Bureau for Statistics. After the exclusion of 122 patients who were lost to follow-up and 481 patients with missing preoperative hemoglobin levels, complete data were obtained in 10 025 patients. Multivariate logistic regression analyses revealed anemia to be an independent risk factor for higher early mortality. Cox regression analyses revealed low hemoglobin level, both as a continuous variable and as a dichotomous variable (anemia), to be a predictor of higher late mortality. Compared with expected survival, patients with the lowest preoperative hemoglobin levels had a worse outcome, whereas patients with the highest hemoglobin levels had a better outcome. Conclusions— A lower preoperative hemoglobin level is an independent predictor of late mortality in patients undergoing CABG, whereas anemia is a risk factor for early and late mortality. Compared with the general population, anemic patients had worse survival than expected, whereas nonanemic patients had better survival than expected.

Patient Blood Management in Europe

“…59 Inappropriate transfusion practices may endanger patients and waste resources. A recent RCT demonstrated that a liberal transfusion strategy (a higher Hb threshold of 10 g dl 21 ) did not improve outcomes (death, inability to walk independently at a 60 day follow-up and in-hospital mordibity) compared with a restrictive strategy (Hb threshold of ,8 g dl 21 ), in a population of high-risk patients after hip-fracture surgery. 60 …”

“…11 12 A recent retrospective cohort study demonstrated a higher postoperative 30 day morbidity and mortality in patients who underwent major non-cardiac surgery with preoperative anaemia than in those without anaemia. 13 In elderly patients with hip fracture, anaemia (Hb ,12 g dl 21 for females and ,13 g dl 21 for males) was significantly associated with 2-to 5-and 3-fold increases in the multivariate-adjusted risk of 6 and 12 month mortality, respectively. 14 Patients with Hb ,10 g dl 21 were at a 5-fold increased risk of death.…”

“…13 In elderly patients with hip fracture, anaemia (Hb ,12 g dl 21 for females and ,13 g dl 21 for males) was significantly associated with 2-to 5-and 3-fold increases in the multivariate-adjusted risk of 6 and 12 month mortality, respectively. 14 Patients with Hb ,10 g dl 21 were at a 5-fold increased risk of death. Subsequent studies have confirmed the association between preoperative anaemia and postoperative mortality in this population, 15 16 and in patients undergoing other types of surgery.…”

“…9 10 Prospective and retrospective cohort studies have consistently shown that patients with preoperative anaemia have poorer postoperative outcomes than non-anaemic patients. Early data suggested that severe preoperative anaemia (Hb ,8 g dl 21 ) independently predicted postoperative mortality in patients undergoing various unspecified types of surgery. 11 12 A recent retrospective cohort study demonstrated a higher postoperative 30 day morbidity and mortality in patients who underwent major non-cardiac surgery with preoperative anaemia than in those without anaemia.…”

“…16 In addition, anaemia is a risk factor for both early and late mortality in patients undergoing coronary artery bypass grafting (CABG). 21 Transfusion may be regarded as the default therapy for anaemia, as it is considered as safe and is rapidly effective. However, accumulating, there is increasing evidence that the correction of preoperative anaemia using transfusion is associated with risks that may contribute to morbidity and mortality in surgical patients.…”