Associations between persistent postoperative anaemia and mortality 1 year after valvular heart surgery: a retrospective cohort study*

Abstract

SummaryIntroductionPeri‐operative anaemia is a common problem in patients undergoing cardiac surgery. Postoperative anaemia is not well understood relative to pre‐operative anaemia; limited data exist on haemoglobin recovery and mortality after discharge, especially in the era of restrictive transfusion practice. We aimed to investigate the associations of pre‐operative and persistent postoperative anaemia with 1‐year mortality in patients undergoing valvular heart surgery.MethodsWe identified patients who had undergone valvular heart surgery and allocated them to one of four groups based on their pre‐operative (haemoglobin ≥ 130 g.l‐1 and < 130 g.l‐1 in men and ≥ 120 g.l‐1 and < 120 g.l‐1 in women) and postoperative (measured 2 months after surgery; haemoglobin ≥ 100 g.l‐1 and < 100 g.l‐1 in both men and women) anaemia status. The four groups were: pre‐ and postoperative non‐anaemia (non‐anaemia–non‐anaemia); pre‐operative anaemia–postoperative non‐anaemia (anaemia–non‐anaemia); pre‐ and postoperative anaemia (anaemia–anaemia); and pre‐operative non‐anaemia–postoperative anaemia (non‐anaemia–anaemia). The primary outcome was 1‐year mortality.ResultsData from 2486 patients were included. Pre‐operative anaemia was diagnosed in 1107 patients (44.5%) and 279 (11.9%) met the diagnostic criteria for persistent anaemia 2 months postoperatively. The overall 1‐year mortality rate was 3.3%. The highest rate was observed in the anaemia–anaemia group (17.8%), followed by the non‐anaemia–anaemia (13.1%), anaemia–non‐anaemia (2.9%) and non‐anaemia–non‐anaemia (0.5%) groups. Multivariable Cox regression analysis showed that the non‐anaemia–anaemia group had the highest risk of 1‐year mortality (adjusted hazard ratio 14.44, 95%CI 4.88–42.69), followed by the anaemia–anaemia group (adjusted hazard ratio 10.94, 95%CI 4.41–27.16).DiscussionOur study highlights the high prevalence of persistent anaemia following valvular heart surgery. Persistent anaemia 2 months postoperatively is associated with an increased risk of 1‐year mortality.