O-208 - THE EFFECT OF PREOPERATIVE ANAEMIA ON PATIENT OUTCOMES AFTER SURGICAL REVASCULARISATION FOR PAD

TOPIC:
Peripheral Occlusive Arterial Disease
AUTHORS:
Birmpili P. (Clinical Effectiveness Unit, Royal College of Surgeons of England ~ London ~ United Kingdom) , Cromwell D. (Clinical Effectiveness Unit, Royal College of Surgeons of England ~ London ~ United Kingdom) , Atkins E. (Clinical Effectiveness Unit, Royal College of Surgeons of England ~ London ~ United Kingdom) , Li Q. (Clinical Effectiveness Unit, Royal College of Surgeons of England ~ London ~ United Kingdom) , Johal A. (Clinical Effectiveness Unit, Royal College of Surgeons of England ~ London ~ United Kingdom) , Waton S. (Clinical Effectiveness Unit, Royal College of Surgeons of England ~ London ~ United Kingdom) , Pherwani A. (Royal Stoke University Hospital ~ Stoke-on-Trent ~ United Kingdom) , Williams R. (Freeman Hospital, Newcastle Upon Tyne Hospitals NHS Foundation Trust ~ Newcastle-upon-Tyne ~ United Kingdom) , Richards T. (Department of Vascular Surgery, University of Western Australia ~ Perth, Western Australia ~ Australia) , Nandhra S. (Freeman Hospital, Newcastle Upon Tyne Hospitals NHS Foundation Trust ~ Newcastle-upon-Tyne ~ United Kingdom)
Introduction:
Anemia in patients undergoing surgery is associated with adverse perioperative outcomes and mortality (1, 2). However, the effect of anaemia on vascular-specific outcomes such as amputation has not been evaluated in large studies. The purpose of this study was to explore the association between the presence of preoperative anaemia and postoperative outcomes after surgical revascularisation for peripheral arterial disease (PAD), using National Vascular Registry (NVR) and linked administrative data.
Methods:
Data from the National Vascular Registry (NVR), a clinical database of vascular procedures in the United Kingdom, were interrogated for all patients that underwent open surgical lower limb revascularisation between January 2016 and December 2019. Those undergoing amputations or endovascular revascularisation procedures in the 30 days prior to the first surgical revascularisation within the study period and procedures due to trauma were excluded. Patient demographics and procedural details were extracted from the NVR, while 30-day and 1-year outcome data were extracted from linked Hospital Episodes Statistics (HES) database, a national administrative database in England, with follow-up to December 2020. Complete case analysis was performed. Four categories of anaemia severity were defined using the WHO criteria for men and women (3). The primary outcome was 1-year amputation-free survival (AFS). Secondary outcomes were length of in-hospital stay, and 30-day AFS, mortality and ipsilateral major lower limb amputation (MLLA) rate. Multinomial logistic regression was used to analyse the effect of anaemia on 30-day outcomes and a flexible parametric survival model was used to estimate the effect of anaemia on 1-year amputation-free survival, adjusting for patient and admission characteristics.
Results:
Some 11,680 patients were included in the study, 8,682 (74.3%) of which were men, 4,304 (36.9%) were admitted non-electively and 4,945 (42.3%) had anaemia (Table 1). Preoperative anaemia was associated with increased median length of hospital stay (10 days [IQR 5-21] for anaemic patients vs. 6 days [IQR 3-10] for non-anaemic, p<0.001). Overall 30-day mortality rate was 2.56%, 30-day MLLA rate 3.19%, 30-day AFS 94.46% and 1-year AFS 80.94%. Preoperative anaemia was associated with worse 1-year amputation-free survival, with increasing severity related to decreasing AFS (Figure 1). After adjustment for age, gender, American Society of Anaesthesiologists (ASA) grade, smoking, diabetes, respiratory, cardiac and renal comorbidities, white cell count, as well as mode of admission and presenting problem (Fontaine stage), patients with anaemia were at increased risk of 1-year amputation or death with a hazard ratio of 1.45 (1.32-1.58) (Table 2). Preoperative anaemia was also associated with worse 30-day amputation-free survival (adjusted estimates 93.79 [95% CI 93.22-94.37] vs. 95.31 [94.73-95.89] for non-anaemic patients). Patients with preoperative anaemia had 1.5 times (95%CI 1.16-1.87) higher relative risk of 30-day ipsilateral major amputation, after adjusting for the same factors and creatinine levels (Table 2). The effect of anaemia severity on 30-day outcomes, adjusting for patient and admission factors is depicted in Figure 2, with moderate and severe anaemia having statistically significant impact on 30-day mortality and amputation.
Conclusion:
In a large contemporary registry data set, this study confirms that preoperative anaemia is significantly associated with increased 30-day mortality rate and amputation rate and decreased 1-year amputation-free survival for patients undergoing surgical revascularisation procedures. Despite national recommendations (4), anaemia correction remains an under-considered factor for optimisation for patients in the perioperative period and further studies are warranted in this area.
References:
1. Fowler AJ, Ahmad T, Phull MK, Allard S, Gillies MA, Pearse RM. Meta-analysis of the association between preoperative anaemia and mortality after surgery. British Journal of Surgery. 2015;102(11):1314-1324. 2. Hogan M, Klein AA, Richards T. The impact of anaemia and intravenous iron replacement therapy on outcomes in cardiac surgery. European Journal of Cardio-Thoracic Surgery. 2014;47(2):218-226. 3. World Health Organisation. Haemoglobin concentrations for the diagnosis of anaemia and assessment of severity. Vitamin and Mineral Nutrition Information System. Geneva: World Health Organization, 2011 (WHO/NMH/NHD/MNM/11.1). Available from: http://www.who.int/vmnis/indicators/haemoglobin 4. National Clinical Guideline Centre. NICE guideline NG24: Blood transfusion. Available from: https://www.nice.org.uk/guidance/ng24
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