Preoperative anemia associated with adverse outcomes after infrainguinal bypass surgery in patients with chronic limb-threatening ischemia

Abstract

Objective Preoperative anemia in elderly patients undergoing surgery is prevalent and associated with adverse events; however, the interaction with other risk factors in patients with chronic limb-threatening ischemia (CLTI) is not well described. The purpose of this study was to assess the association between lower hematocrit (HCT) on admission and postoperative outcomes after infrainguinal bypass surgery. Methods Patients with CLTI undergoing non-emergent infrainguinal bypass were identified in the targeted vascular NSQIP 2011–2014. Thirty-day outcomes were compared across preoperative HCT levels: severe (HCT ≤29%), moderate (HCT 29.1–34%), mild (HCT 34.1–39%), or no anemia (HCT >39%), with no anemia serving as the reference group for all analyses. Independent associations between levels of anemia and postoperative outcomes were established using multivariable logistic regression. A sensitivity analysis was performed to assess interactions between preoperative anemia and blood transfusions. Results We identified 5,081 patients undergoing bypass, of which 741 (15%) had severe, 1,317 (26%) moderate, 1,516 (30%) mild, and 1,507 (30%) no anemia. Anemic patients were older and more commonly suffered from tissue loss and comorbidities (e.g. hypertension, diabetes, and renal insufficiency) (all P<.001). After adjustment for baseline conditions, mortality was higher in those with severe (3.1%, OR: 2.8, [95% CI: 1.3–6.3]) and moderate anemia (3.0%, OR: 2.6 [1.2–5.5]) compared to those without anemia (0.7%). Severe anemia was independently associated with major amputation (6.9% vs. 3.3%, OR: 1.6 [1.01–2.6]) compared to no anemia. Anemia on admission was additionally associated with several other adverse outcomes, such as major adverse cardiovascular event (MACE) (severe: OR: 1.9 [1.1–3.0]; moderate: OR: 1.9 [1.3–2.9]; mild: OR: 1.6 [1.1–2.4]) and unplanned return to the operating room (severe: OR: 1.6 [1.2–2.1]; moderate: OR: 1.5 [1.2–1.8]; mild: OR: 1.3 [1.03–1.6]). Moreover, mortality associated with preoperative anemia was not different in patients receiving postoperative blood transfusions compared to those who did not, while MACE was significantly higher in patients with preoperative anemia and blood transfusions (interaction; P < .001) Conclusions Mortality and major adverse events in CLTI patients undergoing infrainguinal bypass are inversely associated with preoperative hematocrit levels, with the highest event rates in the most severely anemic patients. The correlation between anemia and MACE – but not mortality – was stronger in those patients receiving postoperative blood transfusions. Further research is needed to define an appropriate transfusion threshold and attention should be focused on how to best optimize anemic CLTI patients prior to intervention.

Low vs high hemoglobin trigger for transfusion in vascular surgery: a randomized clinical feasibility trial

“…Fluid resuscitation with red blood cells (RBCs) plays a fundamental role in maintaining tissue oxygenation during blood loss. This is particularly relevant for the vascular surgical patient because of frequent preoperative anemia 1,2 and surgical hemorrhage exceeding 500 mL, [3][4][5] both of which are associated with improved survival if RBC transfusion is initiated during surgery compared with no transfusion. 6 Furthermore, as these patients often present with cardiac disease, [7][8][9] they may be particularly vulnerable to a hemoglobin (Hb) level below 10 g/dL.…”

Clinical practice guideline: evidence, recommendations and algorithm for the preoperative optimization of anemia, hyperglycemia and smoking

“…29 A National Surgical Quality Improvement Program (NSQIP) study of 5081 patients undergoing vascular surgery showed increased mortality for both moderate (OR 2.6, 95% CI 1.2-5.5) and severe (OR 2.8, 95% CI 1.3-6.3) anemia. 30 Preoperative anemia is independently associated with early postoperative complications such as increased overall 30-day postoperative morbidity in patients under going noncardiac surgery (OR 1.35, 95% CI 1.30-1.40), 9 increased rates of major cardiac events (5.1%-6.8% v. 2.6%; p = 0.001) and acute kidney injury (52.0%-63.2% v. 31.0%; p = 0.01) in patients undergoing vascular surgery, 30,31 and increased infectious complication rates in patients undergoing orthopedic surgery (57.1% v. 6.3%; p = 0.006) 32 and those with gastric cancer (OR 3.70, 95% CI 1.43-9.58). 33 In a large NSQIP database study, preoperative anemia in patients undergoing colorectal surgery was independently associated with a significantly increased frequency of composite outcome events (myocardial infarction, acute renal injury, stroke and death) that was proportional to anemia severity (mild: OR 1.…”

Anaemia: A risk factor for death and adverse outcomes following surgery for acute lower limb ischaemia

“…These are some of the only data assessing the effects of anaemia in ALI patients, and our findings are paralleled by studies of patients undergoing lower limb vascular surgery for CLTI, showing similar negative associations with survival, complications and limb loss. 9,11,20 Whilst the acute nature of ALI makes pre-operative optimisation difficult (especially given uncertainty over the benefit of pre-operative transfusion), our analysis demonstrates divergence in survival between anaemic and non-anaemic groups beyond the acute phase of illness. This suggests that there is benefit to be derived from non-transfusion treatment with a latent effect (e.g.…”

“…15 There is also some evidence that both length of stay and infection rates may also be reduced, without change in overall mortality. 16 The acute nature of ALI means that the correction of anaemia peri-operatively is limited largely to red blood cell transfusion which may be associated with increases in mortality 17–19 and complication rates 20 though some analyses do not demonstrate this effect. 21…”