Differential associations between preoperative anaemia and postoperative outcomes in women and men undergoing surgery^✰.

Abstract

Preoperative anaemia is associated with adverse surgical outcomes, yet it is unclear whether anaemia-outcome relationships are consistent for women and men. This observational cohort study was conducted between August 1, 2012 and July 31, 2022 in adults undergoing surgery requiring postoperative hospitalisation at a large academic medical centre in the USA. Anaemia was defined as haemoglobin <12 g dl^-1 in women or <13 g dl^-1 in men. Multivariable regression models assessed associations between preoperative anaemia severity and postoperative outcomes, including a primary outcome of postoperative acute kidney injury (AKI), with interactions evaluated by gender. Of 228 341 procedures (49.4% among women) included, AKI occurred in 13.2% overall, with a lower rate in women (7.6% in women vs 18.8% in men). Preoperative anaemia was present in 70 968 (31.1%) patients, including 30.8% of women and 31.4% of men. In adjusted analyses, increasing severity of preoperative anaemia was associated with worse outcomes. When comparing severe preoperative anaemia to no anaemia, the adjusted odds ratio (OR) for AKI was 2.91 (95% confidence interval: 2.47, 3.44) in women vs 1.43 (1.22, 1.68) in men. Corresponding ORs were 2.48 (2.14, 2.88) vs 1.62 (1.40, 1.86) for ischaemic events, and 4.78 (3.94, 5.80) vs 2.62 (2.13, 3.23) for surgical site infection. Interaction testing confirmed stronger associations in women for AKI, ischaemic events, and surgical site infection (all interaction P<0.001). Preoperative anaemia is associated with adverse outcomes in both women and men, though the associations with acute kidney injury, ischaemic events and surgical site infection are stronger in women.