The effects of preoperative moderate to severe anaemia on length of hospital stay: A propensity score-matched analysis in non-cardiac surgery patients

Eur J Anaesthesiol. 2021 Jun 1;38(6):571-581. doi: 10.1097/EJA.0000000000001412.


Background: Anaemia is frequently recorded during preoperative screening and has been suggested to affect outcomes after surgery negatively.

Objectives: The objectives were to assess the frequency of moderate to severe anaemia and its association with length of hospital stay.

Design: Post hoc analysis of the international observational prospective 'Local ASsessment of VEntilatory management during General Anaesthesia for Surgery' (LAS VEGAS) study.

Patients and setting: The current analysis included adult patients requiring general anaesthesia for non-cardiac surgery. Preoperative anaemia was defined as a haemoglobin concentration of 11 g dl-1 or lower, thus including moderate and severe anaemia according to World Health Organisation criteria.

Main outcome measures: The primary outcome was length of hospital stay. Secondary outcomes included hospital mortality, intra-operative adverse events and postoperative pulmonary complications (PPCs).

Results: Haemoglobin concentrations were available for 8264 of 9864 patients. Preoperative moderate to severe anaemia was present in 7.7% of patients. Multivariable analysis showed that preoperative moderate to severe anaemia was associated with an increased length of hospital stay with a mean difference of 1.3 ((95% CI 0.8 to 1.8) days; P < .001). In the propensity-matched analysis, this association remained present, median 4.0 [IQR 1.0 to 5.0] vs. 2.0 [IQR 0.0 to 5.0] days, P = .001. Multivariable analysis showed an increased in-hospital mortality (OR 2.9 (95% CI 1.1 to 7.5); P = .029), and higher incidences of intra-operative hypotension (36.3 vs. 25.3%; P < .001) and PPCs (17.1 vs. 10.5%; P = .001) in moderately to severely anaemic patients. However, this was not confirmed in the propensity score-matched analysis.

Conclusions: In this international cohort of non-cardiac surgical patients, preoperative moderate to severe anaemia was associated with a longer duration of hospital stay but not increased intra-operative complications, PPCs or in-hospital mortality.

Trial registration: The LAS VEGAS study was registered at, NCT01601223.

Publication types

  • Observational Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anemia* / diagnosis
  • Anemia* / epidemiology
  • Humans
  • Length of Stay
  • Postoperative Complications / diagnosis
  • Postoperative Complications / epidemiology
  • Propensity Score
  • Prospective Studies

Associated data