Low pre-operative hemoglobin levels predict late mortality after CABG
MedWire News: Patients have a worse long-term outcome after undergoing coronary artery bypass grafting (CABG) if they have low pre-operative hemoglobin levels, say researchers.
This was true when pre-operative hemoglobin level was used as both a continuous variable and as a dichotomous variable together with anemia, with a cutoff point of 13 g/dL for men and 12 g/dL for women.
However, only anemia predicted poor short-term outcomes, report Mohamed Soliman Hamad (Catharina Hospital, Eindhoven, The Netherlands) and colleagues.
They assessed early and late mortality, defined as death due to any cause within the first 30 days after CABG surgery and beyond 30 days postoperatively, respectively, in 10,025 patients.
The patients were divided into four groups based on their pre-operative hemoglobin levels: 6.3% of patients in the very-low-hemoglobin group (<12 g/dL for men and <11 g/dL for women); 9.7% in the low-hemoglobin group (≥12 and <13 g/dL for men and ≥11 and <12 g/dL for women); 43.8% in the normal-hemoglobin group (≥13 and <14.5 g/dL for men and ≥12 and <13.5 g/dL for women); and 40.2% in the high-normal hemoglobin group (≥14.5 g/dL in men and ≥13.5 g/dL in women).
Early and late deaths occurred more frequently in the groups with lower pre-operative hemoglobin levels, with an annual incidence of 7.8 per 100 patient-years in the very-low group, 5.3 in the low group, 2.6 in the normal group, and 1.8 in the high-normal group.
Multivariate logistic regression analyses indicated that pre-operative anemia, but not low hemoglobin levels, independently predicted early mortality.
However, low pre-operative hemoglobin levels, both as a continuous variable and as a dichotomous variable with anemia, as well as anemia alone, independently predicted the risk for late mortality.
Indeed, the researchers note in the journal Circulation that “patients with a normal pre-operative hemoglobin level had a better long-term survival than age- and sex-matched groups of the general Dutch population.”
They add that, “although this information has no significance in pre-operative assessment and decision making, it gives patients a rough idea of their long-term prognosis.”
Hamad et al conclude: “The predictive value of pre-operative hemoglobin level indicates the importance of better investigation and management of pre-operative anemia in coronary surgery patients.”
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By Lucy Piper